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Recommendations of the International Task Force for Disease Eradication

Summary

This report summarizes the conclusions of the International Task Force for Disease Eradication (ITFDE), a group of scientists who were convened by a secretariat at the Carter Center of Emory University six times during 1989-1992. The purpose of the ITFDE was to establish criteria and apply them systematically to evaluate the potential eradicability of other diseases in the aftermath of the Smallpox Eradication Program. The ITFDE defined eradication as "reduction of the worldwide incidence of a disease to zero as a result of deliberate efforts, obviating the necessity for further control measures."

The names of the members of the ITFDE, the criteria they developed and used, and summaries of the papers that were presented to the ITFDE by various experts are included in this report, as well as a brief history of the concept of disease eradication since the late 19th century. The ITFDE considered more than 90 diseases and reviewed 30 of these in depth, including one noninfectious disease. It concluded that six diseases -- dracunculiasis, poliomyelitis, mumps, rubella, lymphatic filariasis, and cysticercosis -- could probably be eradicated by using current technology. It also concluded that manifestations of seven other diseases could be "eliminated," and it noted critical research needs that, if realized, might permit other diseases to be eradicated eventually. The successful eradication of smallpox in 1977 and the ongoing campaigns to eradicate dracunculiasis by 1995 and poliomyelitis by 2000 should ensure that eradication of selected diseases will continue to be used as a powerful tool of international public health.

INTRODUCTION

This issue of MMWR Recommendations and Reports consolidates the deliberations of the International Task Force for Disease Eradication (ITFDE), which was convened six times from 1989 through 1992 to evaluate diseases as potential candidates for global eradication (1-7). CDC supports the findings in this report, which indicate a need for greater recognition of the potential to eradicate targeted diseases. Three reports, covering results of the first five meetings, were published previously in the MMWR (1-3), and reprinted in WHO's Weekly Epidemiological Record (4-6). A report of the sixth meeting was also published in the Weekly Epidemiological Record (7).

Eradication is defined as reduction of the worldwide incidence of a disease to zero as a result of deliberate efforts, obviating the necessity for further control measures. The criteria that the ITFDE developed and their conclusions after reviewing more than 90 diseases are presented in this report.

An important part of the work was to help identify key impediments to improved prevention and control of the diseases under discussion, even if the disease was not considered to have potential as a candidate for eradication. One such "noneradication outcome" was the impetus that the members of the ITFDE gave to initiating a demonstration project to control intestinal parasites among schoolchildren in Ghana.

A SPECTRUM OF DISEASE CONTROL

Between the extremes of disease "control" (reduction in incidence and/or prevalence) and "eradication," several intermediate levels of impact on diseases may be described. The term "elimination" is sometimes used synonymously with "eradication," but it refers to a single country, continent, or other limited geographic area, rather than global eradication. True eradication usually entails eliminating the microorganism itself or removing it completely from nature, as in the case of smallpox virus, which now exists only in storage in two laboratories. It is also theoretically possible to "eliminate" a disease in humans while the microbe remains at large, as in the case of neonatal tetanus, for which the World Health Organization (WHO) in 1989 declared a goal of global elimination by 1995.

Although a disease itself may remain, a particularly undesirable clinical manifestation of it may be prevented entirely. Examples of this level of eradication are the use of chemotherapy with ivermectin to eliminate blindness resulting from onchocerciasis and of vitamin A to eliminate xerophthalmia. Eliminating transmission of a disease may also be considered, as in the case of yaws, the late noninfectious clinical manifestations remain of which but are not a danger to others. Finally, "elimination" can be defined as control of the manifestations of a disease so that the disease is no longer considered "a public health problem," as an arbitrarily defined qualitative or quantitative level of disease control (e.g., WHO's goal of eliminating leprosy by the year 2000, which is defined as reducing its incidence to a level below one case per 10,000 population).

Even as smallpox was being eradicated, public health authorities recognized that the eradication campaign was possible because of several important characteristics of smallpox and the smallpox vaccine. Smallpox was epidemiologically vulnerable because it had no natural reservoir in species other than humans; the infection was obvious and usually easily diagnosed; the duration and intensity of infectiousness were limited; persons who recovered were immune for life and often permanently scarred; and its transmission was highly seasonal in many areas. The vaccine was safe, effective even in newborns, inexpensive, easily administered, and stable in tropical climates; its effects were long-lasting; and vaccinated persons had a recognizable scar (8).

As a tool for international public health, eradication of well-chosen diseases has two advantages:

  • Eradication is permanent, as are its benefits. In contrast, the costs of control programs continue indefinitely, along with the risks of future exacerbation of the disease following a disaster of natural or human origin. For some diseases, achieving control would require only marginally less effort than that needed to achieve eradication, but control measures would need to be continued indefinitely. Eradication is the ultimate "sustainable" improvement in public health. The recent reimportation of wild poliovirus into the Western Hemisphere more than 18 months since its last known previous occurrence (9) and the possibility of changes in other pathogens in ways that can make them impervious to once-effective control measures (10) would not be of concern had successful eradication campaigns taken place. (Fear of the consequences of emerging resistance of malarial mosquito vectors and of the parasite itself was partly responsible for the precipitous decision in the 1950s to eradicate malaria.)

  • A time-limited goal of eradication allows mobilization of support for a concentrated effort more readily than does a control program- -both within countries where the disease is endemic and internationally. If developed countries have to spend resources to prevent or control importations of the disease (e.g., poliomyelitis, smallpox), such countries have additional incentive to help support an eradication campaign.

Participation in a successful eradication campaign can also be effective in improving the morale and performance of workers in public health, although this potential benefit can also be derived from a control program. An eradication campaign requires complete surveillance, rigorous administration, and operational research to a degree that may not be necessary in a control program because the standard of success in an eradication program is unambiguous and uncompromising. Another requirement of an eradication campaign may be funding to support measures to eliminate a minor focus of disease from a country where the disease has limited impact and does not constitute a national priority.

The potential negative effects of an eradication campaign, especially an unsuccessful one, must also be weighed. One study stressed the economic consequences and the potential negative impact on broader public health programs (11). The possible effects of competition for scarce resources and the political implications are among the factors that should be considered (12).

The ITFDE developed specific criteria to consider the potential for eradication of diseases other than smallpox (Table_1). These criteria acknowledge that combinations of favorable characteristics other than those that obtained for smallpox might permit other diseases to be eradicated. They generally include elements similar to previously suggested criteria (11,12); however, the criteria of the ITFDE distinguish scientific feasibility from sociopolitical feasibility.

A BRIEF HISTORY OF DISEASE ERADICATION

Every friend of humanity must look with pleasure on this discovery {smallpox vaccination}, by which one evil more is withdrawn from the condition of man; and must contemplate the possibility that future improvements and discoveries may still more and more lessen the catalogue of evils. Thomas Jefferson, 1800

The eventual eradication of smallpox as a result of the use of Jennerian vaccination was predicted by Edward Jenner, as well as by Thomas Jefferson, in the early 19th century. Following the emergence of the germ theory and more systematic approaches to disease control in the mid-19th century, the concept of eradication of a disease first became popular briefly around the turn of the century. Milestones in the history of disease eradication over the years have been summarized (Table_2). Contagious pleuropneumonia of cattle, a disease that had been imported into the United States in 1843, was declared eradicated from the country in 1892, following a 5-year, $2-million campaign to identify and slaughter infected animals (13).

The Rockefeller Foundation began campaigns to eradicate hookworm in 1907 and yellow fever in 1915. Both these campaigns against diseases of humans failed: the hookworm campaign because mass treatment of affected populations with anthelmintic therapy reduced the severity of individual infections but rarely eliminated them and thus did not prevent rapid reinfection (14); and the campaign against yellow fever because of the previously unknown, inaccessible cycle of disease among nonhuman primates living in forests (15). Acceptance of the concept of eradication declined during the late 1920s and early 1930s, after the futility of the eradication of hookworm and yellow fever was recognized.

The concept became popular again in the late 1940s, following the elimination of Anopheles gambiae mosquitoes from Brazil and Egypt, the elimination of malaria from Sardinia, reductions in the prevalence of yaws in Haiti, and the introduction of a stable freeze-dried vaccine against smallpox (13,15). By 1955, WHO had declared goals of global eradication of yaws and malaria, and in 1958 it adopted the goal of smallpox eradication as well. The yaws campaign failed, partly because persons with inapparent latent cases were not adequately treated, in addition to persons with clinical disease. Many such latent infections relapsed to produce infectious lesions soon after mass treatment teams visited a community. Later, disease-specific control measures were withdrawn prematurely, allowing the infection to reappear in several areas (16).

Failure to achieve malaria eradication, after an expenditure estimated at $1.4 billion during the period 1955-1965, brought the concept of eradication into disfavor again (17). Resistance of some vectors to insecticides and of some parasites to treatment, the unexpected diversity and tenacity of some vectors, administrative shortcomings, and rising costs were all factors in the decision to abandon the goal of eradicating malaria (18). (WHO officially revised the goal to one of control in 1969.) The achievement of global smallpox eradication in 1977 and its official certification by WHO in 1980 did not at first bring about the acceptance of the concept of eradication. Concerns were raised that a new eradication effort might detract from efforts to focus attention on the need for developing comprehensive primary health services, rather than focusing on one or two diseases (19). However, several diseases (e.g., schistosomiasis, rotavirus diarrhea, brucellosis, and leprosy) that were then being considered as possible targets for global eradication did not have potential for success given the current technology. Several reports and conferences have considered the potential for eradicating other diseases, of which poliomyelitis, mumps, and rubella were among those most frequently cited (18,20-23). Reports in 1980 and 1985 both concluded that no other major disease was then a potential candidate to be targeted by a global eradication campaign (18,20).

After the concept of eradication was accepted again in the late 1980s, some observers considered a disease to be unsuitable for eradication to the extent that it differed from smallpox or that the intervention against it differed from smallpox vaccine (24). In this third period of acceptance, WHO has targeted dracunculiasis and poliomyelitis for eradication.

SUMMARY OF THE ITFDE DELIBERATIONS

Ninety-four infectious diseases were screened by the ITFDE (Appendix 1). The ITFDE considered 29 infectious diseases in depth, as well as one noninfectious condition (iodine deficiency). The latter condition was chosen in part to enable the ITFDE to apply the criteria it had developed to at least one noninfectious candidate for eradication, as an example in principle. Some infectious diseases that were already proposed for eradication by WHO or by other organizations or countries were considered by the ITFDE before the list was completed. Those diseases were not included in the list of diseases subjected to preliminary screening by the ITFDE.

Of the ninety-four diseases that were screened, the ITFDE concluded that six were potentially eradicable: dracunculiasis (Guinea worm disease), poliomyelitis, mumps, rubella, lymphatic filariasis, and taeniasis/cysticercosis (pork tapeworm). Of these, only the first two had already been targeted for global eradication. The ITFDE also noted that seven other conditions or clinical manifestations of diseases might be eliminated: blindness from onchocerciasis, urban rabies, transmission of yaws and other endemic treponematoses, transmission of hepatitis B, transmission of neonatal tetanus, blindness from trachoma, and iodine deficiency disorders. Key obstacles to eradication, elimination, or improved control were also highlighted by the ITFDE in its discussions of the 30 diseases that it considered in depth (Table_3).

Summaries * of the 30 background papers that were presented to the ITFDE appear below. At least two of the papers prepared for meetings of the ITFDE have been published or accepted for publication (25,26).

Diseases Targeted for Eradication

Dracunculiasis (Guinea Worm Disease)

Dracunculus medinensis now affects as many as 2 million persons in India, Pakistan, and approximately 16 African countries, where greater than 100 million persons are at risk for the disease (27). Persons are infected by drinking water containing immature forms of the parasite. A year later, the female adult worms, each about 1 meter long, emerge through the skin, causing crippling pain that prevents these persons from carrying out their daily activities for periods of weeks or months. When infected persons wade or bathe, the immature forms of the worms enter the water to continue the cycle. Most infections, which induce no immunity and may affect over half a village's population during planting or harvest seasons, are not fatal, but secondary bacterial infections may be life threatening.

Dracunculiasis can be prevented by teaching residents of areas where the disease is endemic to prevent affected persons from entering drinking water sources and to boil or filter their drinking water; by providing water from safe sources such as wells; or by using a chemical to kill the water fleas that harbor the larval parasite. The global eradication campaign began with the International Drinking Water Supply and Sanitation Decade (1981- 1990). In 1986, the World Health Assembly (WHA) adopted the goal of eliminating dracunculiasis. The goal of eradicating dracunculiasis by 1995 was declared by the WHA in 1991. No technical barriers remain, but more social mobilization and funding are needed.

Poliomyelitis

WHO estimates that about 100,000 cases of paralytic poliomyelitis still occur annually worldwide, mostly in Asia and Africa, with approximately 10,000 deaths (28). For every paralytic case, 100 asymptomatic persons carry the virus and can infect others. This virus is transmitted mostly by airborne droplets from infected persons. Persons who recover are immune. The incidence of poliomyelitis has been reduced as a result of the increases in vaccination rates during the drive to vaccinate at least 80% of the world's infants by December 1990. (About 85% were vaccinated against poliomyelitis.) Protection against poliomyelitis requires three or four injections or oral doses of vaccine.

In 1985, the Pan American Health Organization declared the goal of eliminating poliomyelitis from the Americas by 1990 -- a goal that apparently has been achieved, with the final cases reported from Peru in September 1991. In 1988, the WHA declared the goal of eradicating poliomyelitis from the world by the year 2000. WHO now estimates that the external costs of eradicating poliomyelitis will be about U.S. $1.1 billion. Poliomyelitis eradication appears to be technically feasible and would be facilitated by development of a vaccine that requires fewer doses or is more heat stable. The most urgent need is for adequate supplies of the existing vaccine and additional funding.

Diseases that Could Potentially Be Eradicated

Lymphatic Filariasis

Lymphatic filariasis is caused by any of three species of parasitic worms: Wuchereria bancrofti, Brugia malayi, or Brugia timori (29). Nearly 80 million persons are infected in the tropics and subtropics after long exposure to the bites of certain mosquitoes. Adult worms can live in the lymphatic system for 10-15 years. Female worms discharge microfilariae into the blood, where they can infect other mosquitoes and through them, other humans. Humans are the only reservoir of infection, except for B. malayi, which has a reservoir in nonhuman primates that does not appear to contribute to transmission to humans. Complications include swellings of limbs or other appendages (elephantiasis) from interaction of the parasite with the host's immune system. Many infected persons have no symptoms, and the infection is not fatal.

The impact of this infection and disease has been reduced in several areas by mass treatment of populations with diethylcarbamazine (DEC). DEC also has some adulticide effect. Ivermectin is another effective drug that is inexpensive and easily administered. Some side effects may occur after either drug, which may be administered once a year. Improved tests are needed for detecting and monitoring infection. More data are needed about costs of intervention and the effects of ivermectin mass treatment of onchocerciasis on filariasis in West Africa. This disease may be eradicable by using single doses of invermectin, DEC, and salt containing DEC.

Mumps

Mumps is a viral disease that occurs worldwide and usually affects children (30). It is characterized by fever and painful swelling of the parotid salivary glands. Complications may include orchitis, meningitis, and encephalitis, but inapparent infections are common. Spread by direct contact and airborne droplets, mumps is less contagious than measles or varicella. Humans are the only reservoir of this infection, which confers lifelong immunity. The global impact of mumps is unknown but is perceived to be less than that caused by rubella.

Mumps vaccine is highly effective in a single dose when administered after 1 year of age. Most commonly the vaccine is administered in combination with rubella and measles vaccines as MMR vaccine, which requires refrigeration and is administered by injection. Several countries in the Americas, Western Pacific, and Europe include MMR vaccine among the standard group of vaccines recommended for children. Mumps meningitis reportedly disappeared in Cuba following increased vaccination of young children with MMR vaccine. Additional studies are needed to evaluate the impact of mumps (and rubella) in developing countries, as well as the impact of mumps vaccine, including effects of underimmunization (partial suppression of wild virus). The potential synergy of a combined campaign against mumps along with measles and rubella is perhaps the factor most favoring its eradication. Mumps is probably eradicable with MMR vaccine.

Rubella

Rubella causes mild disease when acquired postnatally, but it can cause severe birth defects in at least 20%-25% of infants born to women infected during the first trimester of pregnancy (31). It occurs worldwide. Most infections are subclinical, but these do not appear to play an important role in transmission. Little is known of the disease's impact in developing countries, but serologic surveys indicate that most African children are immune to the virus by their tenth birthday. There is no animal reservoir of infection, and this disease is less contagious than rubeola.

The live-virus vaccine is effective in a single dose and is often administered as part of a triple vaccine against measles, mumps, and rubella (MMR), so that its marginal cost is extremely small. Use of the vaccine has reduced or interrupted transmisssion in several countries, including Cuba, Sweden, Finland, and the United States. Immunization strategies include universal vaccination of children and susceptible women of childbearing age. The potential for increasing susceptibility in women by underimmunization of children (partial suppression of wild virus) must be avoided. An increasing number of countries include MMR vaccine in their routine immunization services. Rubella can be eradicated, and the availability of the MMR combined vaccine has lowered the marginal costs of rubella eradication. More data regarding rubella's impact in developing countries are needed. A strategy that does not inadvertently increase the number of susceptible women should be used.

Taeniasis/Cysticercosis (Pork Tapeworm)

Human beings are the only definitive hosts of Taenia saginata (beef tapeworm) and Taenia solium (pork tapeworm) (26). The beef tapeworm is associated with cattle husbandry; it is the more widespread of the two and is increasing in Europe. Both species are most prevalent in Latin America, Asia, and Africa. Humans are infected by eating inadequately cooked, contaminated beef or pork. The eggs of T. solium are also infective to humans, who may develop a life-threatening dissemination of larvae to cause cysts in various tissues. Epileptic seizures are a major manifestation when such cysts occur in the brain. Approximately 50 million persons are infected with both parasites; some 50,000 die of cysticercosis annually.

Effective means now exist for surveillance to identify foci of transmission of T. solium and for mass treatment of humans (e.g., praziquantel and niclosamide) to help eliminate such foci. This parasite causes a substantial economic burden to the pork industry. T. solium has disappeared gradually from most European countries even without targeted control measures. Research priorities include development of a more sensitive diagnostic test for use in pigs and a better way to identify infected persons. T. solium cysticercosis is potentially eradicable through surveillance and available interventions, but such feasibility needs to be demonstrated in a sizable geographic area.

Diseases of which Some Aspect Could Be Eliminated

Hepatitis B

Hepatitis B is a viral disease that is responsible for more than 250,000 deaths per year worldwide (32). High incidences are found in Alaska and other arctic areas, Africa, China, Southeast Asia, and the Amazon. Many infections are asymptomatic. Hepatitis B is transmitted in early childhood, often perinatally from mother to infant; sexual and other transmission by direct contact also occur. About 5% of infections occur in utero. More than two thirds of persons infected in infancy become persistent carriers of the virus. Deaths result from liver cancer or chronic liver disease, including cirrhosis.

A vaccine to prevent hepatitis B was introduced in the late 1970s. Three doses are required, beginning at birth or in early infancy in areas where the disease is highly endemic. Some countries have begun routine mass vaccinations of infants against hepatitis B as a part of their Expanded Programme on Immunization. An alternative approach is to vaccinate only infants of infected mothers who have been identified by prior screening. At the current cost of U.S. $7.60 per dose of vaccine, hepatitis B could be eventually eliminated from the United States at a cost of about $120 million per year, compared with an estimated annual cost of $750 million for treating persons who contract the disease. Reduction of disease would not begin to be evident for about 15 years. It is not possible to eradicate hepatitis B now, but it is technically feasible to eliminate its transmission by universal vaccination programs.

Iodine Deficiency Disorders

More than a billion persons are at risk for this noninfectious condition, which is the leading preventable cause of intellectual impairment in the world (33). The number of persons affected is unknown, but prevalences of the most severe form, cretinism, often reach 3%-15% in areas where the disease is highly endemic. Goiter and hypothyroidism are other manifestations of the deficiency. The main risk factor involved is exclusive or nearly exclusive consumption of locally grown foods in areas where the soil is deficient in iodine.

Interventions include adding iodine to salt, tea, fish paste, or bread, at a cost of US $0.02-0.04 per person per year for iodized salt. Iodized oil is available in injectable or oral forms. Interventions for iodine deficiency can also be combined readily with interventions for vitamin A and/or iron deficiency. A new assay is available to measure levels of thyroid hormone in samples of blood from a fingerstick. Methods such as iodized salt were used to eliminate iodine deficiency disorders more than 40 years ago in Australia, England, New Zealand, Switzerland, and the United States. Bolivia and Ecuador have almost eliminated the condition. WHO has endorsed a goal of elimination of iodine deficiency disorder by the year 2000. There is great need for improved surveillance and estimates of the prevalence of these disorders and of their economic impact. Iodine deficiency disorders can be eliminated.

Neonatal Tetanus

WHO estimates that as of 1990 approximately 560,000 deaths caused by tetanus infections in newborns occurred annually in developing countries, mostly in Asia and Africa (34). Newborns are infected by spores of the bacterium Clostridium tetani when the umbilical stump is contaminated by unclean instruments or hands used to cut the cord at birth and/or dressings applied to the area in the first few days of the infant's life. The spores are found widely in the environment, where they are associated with the feces of ungulates. Most infected infants die of the disease.

Neonatal tetanus can be prevented by promoting clean deliveries and by vaccinating women of childbearing age and children. Based on this strategy, in 1989 WHO declared the goal of eliminating neonatal tetanus by 1995. As of 1990, only about 58% of women of childbearing age worldwide (43% in developing countries) had received the two injections of vaccine required to protect their infants. To achieve better control, the number of doses of vaccine required to confer protection should be reduced and surveillance of the disease and monitoring of vaccination coverage should be improved. The reservoir of tetanus spores in the environment is the major barrier to elimination of neonatal tetanus, which cannot be eradicated. Preventing transmission of this disease by continuing the interventions mentioned above, however, is possible.

Onchocerciasis (River Blindness)

Onchocerciasis is caused by a parasitic worm, Onchocerca volvulus, which is transmitted to persons by biting blackflies that breed in fast-flowing rivers (25). The adult worms live for up to 15 years in nodules beneath the skin and muscles of infected persons, where they produce millions of embryos (microfilariae) that invade the skin, eyes, and other tissues. Some microfilariae are taken up from the skin by blackflies to continue the reproductive cycle. About 18 million persons are affected, mostly in Africa (99%), Yemen, and Latin America. Both living and dead microfilariae cause severe itching in the skin and sometimes blindness after many years. Approximately 340,000 persons have become blind from the disease.

Until the 1980s, the main control measure was to use larvicides to kill immature blackflies in rivers. This method has been used effectively by the multicountry Onchocerciasis Control Program to reduce the incidence of the disease in part of West Africa over the past 2 decades, but it is expensive. Since 1987, the drug ivermectin has been provided by the manufacturer free of charge to control programs for treating persons with onchocerciasis. This treatment is effective in a single oral dose, administered once annually; it prevents accumulation of microfilariae in persons at risk. No drug suitable for mass treatment can kill the adult worms in the host's body, and onchocerciasis cannot be eradicated without such a means. The blindness, however, can be eliminated.

Rabies

More than 50,000 persons die of rabies each year, mostly in China and India (35). Humans are infected by saliva introduced into wounds by the bite of a rabid wild or domestic animal, usually a dog. Canine rabies is endemic throughout most of Asia, Africa, and Latin America. Rabies also is endemic among some wild animals (e.g., foxes, raccoons, skunks, and bats) in North America and Europe. Rabies is almost always fatal.

Some developed countries have virtually eliminated rabies in humans by mass vaccination of domestic dogs and destruction of stray dogs. This approach is difficult to apply in rural areas of most developing countries, where animals may not be privately owned, destruction may be unacceptable, and such campaigns may be expensive. Some Latin American countries are conducting successful campaigns in cities, however. Attempts are being made to control rabies in wildlife by development of oral vaccines that can be safely distributed in baits. Eradication of rabies is not feasible, primarily because of the extensive, varied animal reservoirs of the virus and the inability to eliminate those reservoirs through available technology. It is possible to eliminate human rabies in urban areas, although the costs and benefits of doing so should be considered.

Trachoma

Trachoma is a chronic inflammatory disease of the eye caused by repeated infection with certain types of Chlamydia trachomatis, which often results in blindness (36). Approximately 500 million persons are infected worldwide, some 6-8 million of whom have become blind. The disease progresses to blindness in about 5%-20% of the infected population. It is transmitted mainly among children and from them to women, perhaps during child care. Important risk factors include low socioeconomic status and inadequate supplies of water.

Effective interventions include mass treatment with tetracycline ointment, which is effective in the short term. The disease, however, usually returns within 6-12 months to pretreatment levels in a community. Promotion of increased face-washing and surgery of the scarred eyelids to prevent continued damage to the cornea by turned-in lashes are other interventions. There is need for more research into the costs and benefits of interventions, the epidemiology of various risk factors, and documentation of previous successes in control of the disease. It appears scientifically feasible to eliminate blindness caused by trachoma -- but not the infection or agent itself -- by a combination of community-based education to promote face washing and targeted antibiotic treatment.

Yaws and Other Endemic Treponematoses

Each year, approximately 2.5 million persons, mostly children, contract yaws, endemic syphilis, or pinta -- all closely related infections that are transmitted nonsexually, mainly by skin-to-skin contact (37). These diseases rarely are fatal but often disfigure or cripple affected persons by invading their skin, bones, and cartilage. Endemic treponematoses occur in poor rural communities in tropical Africa, Asia, or Latin America. All three diseases are characterized by a positive serologic test that cannot be distinguished from the positive test caused by venereal syphilis. For each person with obvious skin lesions, two or more persons have latent infections.

Mass treatment campaigns conducted during the 1950s and 1960s with injectable penicillin pushed yaws almost to extinction. Yaws and endemic syphilis have since resurged, especially in West Africa. Serologic testing, treatment with penicillin, and improvement in personal hygiene are the main interventions, all of which could be implemented as a part of primary health care. Similar infections have been seen in a few nonhuman primates but do not appear to be epidemiologically important. Development of tests to reliably distinguish these treponemes and their serologic reactions would facilitate control efforts. The potential for emergence of penicillin-resistant strains lends urgency to the need for better control. Eliminating transmission of these diseases seems feasible.

Diseases that Are Not Eradicable Now

Ascariasis (Roundworm)

Ascariasis, caused by the intestinal parasite Ascaris lumbricoides (large roundworm), is one of the most common infections of humans, affecting an estimated one billion persons at any one time (38). It affects greater than or equal to 50% of populations in tropical and subtropical areas. Its clinical effects include respiratory or abdominal symptoms and discomfort, with or without associated malnutrition, especially in young children. Potential complications include obstruction of the bile duct by a worm or, more commonly, intestinal obstruction by a mass of worms. Globally, ascariasis causes an estimated 20,000 deaths per year. Humans are infected when they ingest soil contaminated (by human feces) with eggs of the parasite on their food, fingers, or drink.

An adult ascaris may live up to one and a half years. Humans are the only reservoir, but the eggs may remain viable in soil for years. Diagnosis requires careful examination of a fecal sample by a trained microscopist. Control measures include sanitation and education to promote using latrines, washing hands and food, and avoiding use of uncomposted human feces as fertilizer; mass chemotherapy; and provision of safe water for household use. Modern anthelmintics administered in a single dose are safe and relatively inexpensive and are effective for several months. Ascariasis is not now eradicable, but it could be better controlled through mass chemotherapy and hygiene education of schoolchildren.

Cholera

Cholera, characterized by severe watery diarrhea, dehydration, and high mortality in untreated cases, is caused by the bacterium Vibrio cholerae 01 (39). Many infections are asymptomatic. Although cholera disappeared from much of the world in the 19th century, the current pandemic of the El Tor cholera biotype has been exacerbated by larger human populations, faster travel, and greater survival in the environment. The disease has appeared in more than 100 countries in the past decade and greater than 70,000 cases were reported to WHO in 1990, but the global prevalence of cholera is unknown. It is associated with unsanitary conditions and may be spread by fecal contamination of food, water, or hands. No effective immunity develops.

There is no known animal reservoir, but foci of the organism are now known to persist for years in aquatic environments in the Gulf of Mexico and eastern Australia. The current vaccine gives only limited protection for several months. Oral rehydration can reduce mortality rates. Antibiotic drugs may shorten the duration of illness and stop excretion of the vibrios. Cholera is not now eradicable, although better control is possible by providing clean water, sanitation, and health education. Priority research needs are to understand the environmental reservoirs better (e.g., how does the organism survive? are there other such foci?) and to understand the molecular basis for differences among strains of V. cholera.

Diphtheria

This disease, caused by infection with Corynebacterium diphtheriae, is characterized by respiratory obstruction and/or myocarditis as a result of a toxin released by some strains of the bacteria. It is spread by direct contact and airborne droplets (40). Less harmful infections of the skin occur more commonly in developing countries. An asymptomatic carrier state may follow infection. In the prevaccine era, diphtheria was a major cause of illness and death in children in urban temperate areas. The global toll is unknown, but cases reported to WHO declined from 77,000 in 1974 to less than 24,000 in 1988. It is not known if the nontoxigenic strain of diphtheria induces immunity to infection. Humans are the only reservoir.

The vaccine is an antitoxin, which usually is administered as a part of the DTP or DT vaccines, in at least three doses administered by injection at 1-month intervals. Booster doses are also necessary. Widespread use of this vaccine has reduced the incidence of diphtheria in developed and many developing countries. In the United States, fewer than five cases were reported annually during the 1980s. No cases were reported in Sweden for a 24-year period. Recently, DTP vaccine has been used more widely in developing countries. There has been a recent resurgence of this disease in Russia. Diphtheria might be eradicable, but its effects in developing countries and the epidemiologic impact of immunization are not completely understood.

Hookworm Disease

Hookworm infections in humans are usually caused by Ancylostoma duodenale or Necatur americanus, which together infect an estimated 900 million persons in tropical and subtropical areas (41). Local prevalence rates vary from 10% to 90%; they peak in the later teenage years and among young adults. Infections become clinically important when enough worms are present to cause anemia from loss of blood as a result of the worms, which live in the intestine. About 60,000 persons die of the infection annually, but many infections do not cause symptoms. Hookworm is transmitted when skin comes into contact with moist soil or vegetation that harbors infective larvae hatched from eggs in the feces of an infected person. Adult worms may live 1-5 years. Larvae in soil remain viable for 3-4 weeks. Humans are the only known reservoir of this infection.

Preventive measures and treatment are similar to those for ascariasis, except that wearing shoes also protects against hookworm larvae and administration of iron supplements can reverse the resultant anemia. Sociologic barriers to control include the association of the disease with poverty, poor personal hygiene and defecation practices, and use of human feces as fertilizer -- all factors that are difficult but not impossible to change. An attempt to eradicate hookworm in the United States early in the 20th century failed, and there is little or no political support for another attempt. Hookworm is not now eradicable.

Leprosy (Hansen's Disease)

This chronic infectious disease caused by Mycobacterium leprae affects an estimated 11-12 million persons worldwide (42). Leprosy is usually nonfatal but may be severely disfiguring and disabling, and affected persons are often ostracized. Prolonged contact with an infected person is required for transmission. Wild infected armadillos shed the bacteria into the soil and may transmit the disease from animal to animal.

The introduction of sulfones for chemotherapy in the 1940s was a major breakthrough, although many years of therapy were required for cure. Combination therapy with two to three drugs has had a major impact on the severity of the disease over the past decade. The new drug regimens are shorter but still require 6-24 months of therapy. Resistance of leprosy bacilli to chemotherapeutic drugs is an increasing problem. China, Japan, and South Korea have rapidly reduced the incidence and prevalence of this disease in recent years. India and China established national programs with goals of halting transmission of leprosy by 2000. In 1991, WHO set the goal of eliminating leprosy (defined as incidence less than 1/10,000 population) worldwide by 2000. This disease is not now eradicable. Impediments include absence of a fast, simple diagnostic test; persistence of organisms, even in treated persons; cost and side effects of drugs; duration of chemotherapy; patient compliance; and the social stigma associated with the disease.

Measles

Almost a million persons, mostly infants and young children, die annually from measles. Especially in Africa, it often leads to death from pneumonia, diarrhea, and malnutrition (43). Measles is highly contagious and spreads by airborne droplets exhaled by infected persons up to 2 days before the characteristic rash appears. Persons who recover are immune to reinfection for life. The successful global campaign to improve vaccination levels by 1990 reduced the incidence of measles substantially. A single injection of vaccine is usually sufficient to confer long-lasting immunity, but to be effective it must be administered after the infant's maternal immunity has waned.

Measles vaccine has been used to reduce the incidence of the disease in the United States, Canada, Cuba, and some European countries, but the disease has not yet been eliminated from any large country. In 1977, the United States established the goal of eliminating measles from the country by 1982. It reduced reported cases to less than 3000 per year from prevaccine levels of greater than 100 times that number, only to have the disease rebound to 25,000 cases in 1990. European and Caribbean countries plan to eliminate measles by 1995. WHO has established the goal of reducing the global incidence of measles by 90% by 1995. The ineffectiveness of the vaccine for infants at birth or soon after and the high degree of contagion of the infection are the principal barriers to eradication of measles.

Pertussis (Whooping Cough)

This disease, caused by the bacterium Bordetella pertussis, occurs worldwide (44). It primarily affects infants and young children, with peak incidence in the first 2 months of life, and is characterized by a severe, protracted cough. Globally, pertussis still causes about 40 million cases and 400,000 deaths annually. It is spread from person to person by direct contact and airborne droplets and is highly contagious. Persons who recover are immune. Humans are the only reservoir of the infection.

Pertussis vaccine is part of the combined Diphtheria-Tetanus-Pertussis vaccine (DTP), which is administered by injection and requires three to four doses to be effective. Use of this vaccine has reduced pertussis incidence by more than 99% in the United States since 1940. The high infectiousness of pertussis, the occurrence of much of its impact within the first 2 months of life, and the need to administer at least three doses of vaccine (each dose at 1-month intervals) to achieve adequate protection are major impediments to control. Better control could result from an improved vaccine (e.g., fewer doses, greater efficacy, and safety for adults), improved diagnostic methods, and study of the epidemiology of pertussis in developing countries. If a safe antigen were available for use in adults, researchers could investigate the possibility of protecting infants by booster vaccination of pregnant women. Pertussis is not now eradicable.

Rotaviral Enteritis

Some 80 million episodes of moderate to severe diarrhea and an estimated 870,000 deaths per year are due to rotavirus, which is the most common cause of severe diarrhea in children (45). It is found in both developed and developing countries. The virus is spread mainly by the fecal-oral route, but the mode of spread among young children is uncertain. Some infections in India may originate from cattle. Infection appears to protect children against subsequent attacks of severe disease.

Improved hygiene, including handwashing, is the main available mode of preventing spread of the disease. Use of oral rehydrating solution can mitigate clinical effects. An effective vaccine is not yet available for preventing this infection. Priority research needs include development of an effective vaccine, studies of the antigenic diversity of strains of the virus in developing countries, development of an animal model, and further investigation of mechanisms of immunity. Rotaviral enteritis is not now eradicable.

Schistosomiasis (Bilharziasis)

Most human infections with this debilitating disease are caused by Schistosoma mansoni, S. japonicum, or S. hematobium (46). All three parasites, except possibly S. hematobium, have important nonhuman reservoir hosts. About 200 million persons are affected in Asia, Latin America, and especially Africa. Infection is usually acquired in childhood, with peak prevalence and intensity among persons 10 to 19 years of age. Untreated, chronic infection may last 3-4 decades. Persons are infected when they enter fresh water sources and larval forms of the parasite penetrate the skin. Such sites are contaminated by egg-bearing feces or urine from infected persons, allowing the worm to enter snails and multiply before becoming infective to humans. Modern dams and irrigation projects have often increased the habitat of the snails.

Modern mass chemotherapy has increased the potential for control of this disease -- as demonstrated already in parts of Brazil, China, and Egypt. Single oral doses of some anthelmintics can decrease worm burdens for greater than or equal to 1 year, depending on the drug and parasite species. Health education to reduce contamination of and exposure to transmission sites and provision of safe water and sanitary facilities are also vital. Schistosomiasis is not now eradicable, but better control is possible, especially by mass chemotherapy and hygiene education for schoolchildren.

Tuberculosis

Tuberculosis (TB) infects 8-10 million persons and kills an estimated 2-3 million annually (47). It occurs in all countries but is an especial public health problem in many developing nations. This bacterial infection is spread from person to person by respiratory droplets, especially in crowded, poorly ventilated conditions. Recently, its spread has been facilitated by the concomitant infection of many patients with human immunodeficiency virus (HIV).

Improved living conditions, case finding, drug treatment, isolation of infectious patients, and selective chemoprophylaxis reduced TB incidence in many industrialized countries in the 20th century. Bacille Calmette-Guerin (BCG) vaccine has been used in some countries to help protect infants and young children from potentially fatal complications of TB. Emergence of strains of Mycobacterium tuberculosis that are resistant to one or more of the drugs used for treating the disease has complicated and hampered control programs in the past few decades. In the late 1980s, the United States declared a goal to eliminate TB in the country by 2010 (defined as an annual case rate of less than 1/1,000,000 population). There is need for more accurate, rapid diagnostic tests; shorter and less expensive therapies; better case finding in persons at risk; and a safer, more effective vaccine. It is not now feasible to eradicate TB.

Yellow Fever

Yellow fever is believed to cause more than 10,000 deaths annually in South America and Africa, but its incidence varies because of sporadic epidemics, in addition to ongoing endemic transmission of the disease (48). It is usually transmitted to humans by bites of Aedes aegypti mosquitos in urban areas or by bites of other mosquito vectors in sylvatic settings. A permanent cycle of the virus is maintained in jungle-dwelling primates.

An effective vaccine has been available for more than 50 years, although it must be refrigerated and administered by injection. It is recently being included in Expanded Programmes of Immunization in some African countries, as recommended by WHO. Research to improve the current vaccine would be helpful. More aggressive use of the current vaccine could stop urban yellow fever and reduce epidemics in rural areas. Because of the sylvatic reservoir of infection, however, yellow fever cannot be eradicated.

Diseases that Are Not Eradicable

Amebiasis

Amebiasis is caused by the protozoan Entamoeba histolytica, a parasite that usually lives in the large intestine of humans, who are its only reservoir (49). Some 500 million persons may be infected worldwide, of whom 38 million may develop serious complications (e.g., liver abcess and colitis); 40,000-110,000 persons may die annually. The disease is associated with specific strains of the parasite that have characteristic enzyme patterns. It is especially prevalent in parts of Latin America, Africa, and Asia. The infection is spread by ingestion of the hardy cysts on food or hands or in contaminated drinking water. Most infected persons are asymptomatic; some may excrete cysts for years.

Diagnosis usually requires examination of fecal specimens by a skilled microscopist. Serologic tests and imaging techniques to detect internal abcesses are also used. Drug therapy can eliminate the parasite in the intestine and other organs, but most such drugs must be administered for several days. Proper disposal of human feces, education of persons at risk, and detection and treatment of infected persons are key interventions. Amebiasis is not now eradicable. Current barriers might be overcome if an effective, safe drug became available that could be administered to large groups in a single oral dose without prior testing. Control would also be facilitated if it can be established that only amoebae from symptomatic persons cause symptomatic disease in others.

Bartonellosis

This bacterial infection (Bartonella bacilliformis) is limited to certain mountainous areas of Peru, Ecuador, and Colombia, where it is transmitted by the bite of an infected sandfly (50). It also can be transmitted by transfusion of blood from an infected person. Infected persons may harbor the bacterium in their blood for many years. The disease may manifest as severe anemia with fever or as a painful skin eruption accompanied by pain in the muscles and joints. The number of persons affected is unknown, but approximately 40% of cases may be fatal and as many as 5% of populations in areas where the disease is endemic may harbor asymptomatic infections. Humans are the only known reservoir of the infection. Persons may remain infective to sandflies for many years.

The infection is diagnosed by microscopic examination of blood or affected skin or by culturing blood on special media. Treatment requires administration of high doses of antibiotics for at least 7 days. The risk of sandfly bites can be reduced by appropriate insecticides and other protective measures. This infection is not eradicable.

Clonorchiasis

This infection (caused by the parasite Clonorchis sinensis) is endemic in parts of China, Japan, Korea, and Southeast Asia (51). More than 20 million persons are infected in China alone. Persons become infected by eating raw or inadequately cooked freshwater fish (e.g., carp species or crayfish). In humans, the parasite lives in the bile ducts, and its eggs are discharged in the feces, sometimes for as many as 30 years. After the eggs are discharged, the parasite must first enter a snail, then a fish as intermediate host. Infection in humans is often asymptomatic, but it can cause abdominal pain, gallstones, and cancer of the biliary tract. Pigs, dogs, cats, and rats are also reservoirs of this parasite. Transmission is most frequent, however, in areas where human feces are used to fertilize fish ponds and where harvested fish are eaten raw.

Diagnosis is made by identifying the eggs in fecal specimens, but the eggs of a similar parasite (Opisthorchis) are identical. Serologic testing is also helpful. Drug treatment for 1-2 days is effective. Preventive measures include proper disposal of human feces and thorough cooking or freezing of freshwater fish for at least 5 days. This infection is not eradicable because of the nonhuman reservoir, the many asymptomatic infections of humans, and the fact that some infected persons can shed eggs for decades. Its prevalence could be reduced, as with that of several other infections, by promotion of sanitary disposal of human feces.

Enterobiasis (Pinworm)

Enterobiasis is an extremely common parasitic infection, often of young children, in temperate and tropical countries (52). Humans are the only hosts of the infection, which is caused by pinworm, Enterobius vermicularis. The tiny adult worms live in the large intestine for greater than or equal to 90 days. They deposit larvae-containing eggs on or near the anus, where their presence causes itching. Children are infected by putting fingers that have been contaminated from scratching into their mouths or by inhaling and then swallowing the eggs, which may become airborne with household dust. The eggs can remain viable in the environment for approximately 2 weeks. Associated pathology is unusual, but the parasite may cause chronic appendicitis or invade the female genital tract.

Diagnosis is made by identifying the microscopic eggs in scrapings or on adhesive tape that has been pressed to perianal skin. Several anthelmintic drugs are effective when administered in a singe oral dose, but infected persons, their families, and other close contacts usually should be treated simultaneously at least twice, at 2-week intervals. It would be nearly impossible to arouse support for the eradication of this widespread infection, since its clinical effects are usually mild or nonexistent.

American Trypanosomiasis (Chagas' Disease)

Approximately 15-20 million persons in impoverished rural areas of the Americas from Mexico to Chile are infected with the parasite Trypanosoma cruzi (53). The infection is transmitted by the bite of a triatomine bug ("kissing bug") or by blood transfusion, after which there is a long latent period with few or no symptoms. Manifestations may include swelling of the eyelid, followed by fever and enlargement of the internal organs. Sudden death due to acute cardiac problems can occur in infected young adults. More than 150 species of domestic and wild animals are hosts of this parasite, of which there are many strains. Many epidemiologically important species of the insect vector live in thatched roofs, cracks in walls, and other dark places.

Housing improvements to reduce suitable habitat for the insect vectors and use of residual insecticides are the main bases for preventive interventions in national control programs. Diagnosis, whether by blood smear or serology, and treatment are difficult. Improved diagnosis, methods for screening blood, and treatment are needed. Chagas' disease is not eradicable at present.

Varicella (Chickenpox) and Zoster

Varicella-zoster virus causes two diseases: varicella, which mainly affects children and causes generalized rash and fever; and zoster, which produces a painful localized rash in adults when latent infection from a prior attack of varicella is reactivated (54). The virus is transmitted by the airborne route from sources in the respiratory tract and skin. Varicella is highly contagious, comparable with measles. Humans are the only reservoir of infection, and most who recover are immune for life. The global toll is unknown, but approximately three million cases of varicella and 300,000 cases of zoster occur annually in the United States alone, including about 100 reported fatal cases. Varicella appears not to spread as much in tropical countries as in the United States.

A live attenuated vaccine is expected to be licensed in the United States soon, but it is not as effective as other common live-virus vaccines. Moreover, the durability of such induced immunity and its potential effect on the incidence of zoster are unknown. Antiviral therapy with acyclovir can accelerate recovery if it is administered early in the course of the disease. Immune globulin is an effective prophylactic if administered soon after exposure to the virus. The main barrier to eradication of this disease is the ability of the virus to reactivate from latency to produce zoster, which is about 25% as infectious as varicella. This infection is not eradicable.

THE FUTURE

The concept and practice of disease eradication are now accepted as useful, respected tools of international public health, to be employed with scientific discretion. The likely achievement of the next two declared targets for global eradication, dracunculiasis by 1995 and poliomyelitis by 2000, together with the precedent already established by the eradication of smallpox in 1977 (1 year later than the target date), should ensure the survival and application of the principle of eradication (Table_2). ** By the time dracunculiasis and poliomyelitis are expected to have been eradicated, interim targets for measles (Table_4) should have been attained and progress should have been made toward the control of other potential targets for eradication that have been identified by the ITFDE (e.g., mumps, rubella, cyticercosis, and lymphatic filariasis). Thomas Jefferson's "catalogue of evils" may be steadily diminished with these attainments and with advances in tools for controlling other potential targets such as onchocerciasis (or Haemophilus influenzae b, for which conjugate vaccines have been licensed).

If the epidemiologic benefits of eradication are not incentive enough, the fiscal rewards may help ensure the concept's acceptability. The United States alone has been recovering its total investment of about $30 million in the global Smallpox Eradication Program every 3-4 months since the early 1970s. Since smallpox was eradicated in 1977, that total investment has been returned to the United States every 26 days. Based on the current rate of progress towards eradication of poliomyelitis, WHO predicts that campaign will "produce {global} savings of half a billion dollars by the year 2000, increasing to U.S. $3 billion annually by the year 2015."

The main obstacle to the concept's current acceptance is that if the concept of eradication is invoked against inappropriate or unattainable targets, it can again be brought into disrepute. The declared targets of "elimination" of neonatal tetanus by 1995 and of leprosy by 2000 are potential examples of such dangers. Care should be taken to reserve use of the terms "eradication" and "elimination" only for carefully chosen diseases that have a high likelihood of being eradicated.

Continued advocacy is required to maintain appropriate consideration of the issues considered and suggestions made by the ITFDE. The Task Force for Child Survival and Development, which includes several key members of the ITFDE, will review updates of this topic annually. If new information or the appearance of new control measures, for example, suggest the need for it, a group may be reconvened to consider other diseases in depth (e.g., H. influenzae b) or reconsider diseases that were discussed by the ITFDE. In the interim, the most urgent task for promoting the concept of disease eradication is to ensure the successful eradication of dracunculiasis by 1995 and of poliomyelitis by 2000.

Acknowledgment

The International Task Force for Disease Eradication (ITFDE) was established in 1988 to systematically review potential candidate diseases for eradication and to provide leadership and advocacy for the concept of eradication where appropriate and useful. The secretariat for the ITFDE was supported by a grant from the Charles A. Dana Foundation to William H. Foege, M.D., M.P.H., then the Executive Director of the Carter Center of Emory University.

References

  1. CDC. International Task Force for Disease Eradication. MMWR 1990;39:209-12,217.

  2. CDC. Update: International Task Force for Disease Eradication, 1990 and 1991. MMWR 1992;41:40-2.

  3. CDC. Update: International Task Force for Disease Eradication, 1992. MMWR 1992;41:691,697-8.

  4. WHO. International Task Force for Disease Eradication. Wkly Epidemiol Rec 1990;65:369-72.

  5. WHO. Update: International Task Force for Disease Eradication, 1990 and 1991. Wkly Epidemiol Rec 1992;67:89-91.

  6. WHO. Update: International Task Force for Disease Eradication, 1992. Wkly Epidemiol Rec 1992;67:344-5.

  7. WHO. Update: International Task Force for Disease Eradication, 1992. Wkly Epidemiol Rec 1993;68:217-9.

  8. Fenner F, Henderson DA, Arita I, et al. Smallpox and its eradication. Geneva: World Health Organization, 1988.

  9. CDC. Isolation of wild poliovirus type 3 among members of a religious community objecting to vaccination -- Alberta, Canada, 1993. MMWR 1993;42:337-9.

  10. CDC. Introduction: emerging infectious diseases. MMWR 1993;42:257.

  11. Hinman EH. World eradication of infectious diseases. Springfield, IL: C.C. Thomas, 1966.

  12. Yekutiel P. Lessons from the big eradication campaigns. World Health Forum 1981;4:465-81.

  13. Cockburn TA. Eradication of infectious diseases. Science 1961;133:1050-8.

  14. Andrews JM, Langmuir AD. The philosophy of disease eradication. Am J Public Hlth 1963;53:1-6.

  15. Soper FL. Rehabilitation of the eradication concept in prevention of communicable diseases. Public Health Rep 1965;80:855- 69.

  16. Hopkins DR. Control of yaws and other endemic treponematoses: implementation of vertical and/or integrated programs. In: JP Burke, et al., eds. International Symposium on Yaws and Other Endemic Treponematoses. Rev Infect Dis 1985;7(suppl 2):338-42.

  17. Gabaldon A. Global eradication of malaria: change of strategy and future outlook. Am J Trop Med Hyg 1969;18:641-56.

  18. Yekutiel P. Eradication of infectious diseases. In: Klinberg MA, ed. Contribution to epidemiology and biostatistics. Vol 2. Basel: S. Karger Verlag, 1980.

  19. Mahler H. Introduction. In: The work of WHO, 1978-1979. Geneva: World Health Organization, 1980.

  20. Evans AS. The eradication of communicable diseases: myth or reality? Am J Epidemiol 1985;122:199-207.

  21. Langmuir AD. Prospects for eradication of viral diseases by immunization. In: Proceedings of the International Conference on the Application of Vaccines against Viral, Rickettsial, and Bacterial Diseases of Man. Washington, DC: Pan American Health Organization, 1970.

  22. Hinman AR. Prospects for disease eradication or elimination. NY State J Med 1984;84:502-6.

  23. Stuart-Harris C, Western KA, Chamberlayne EC. Can infectious diseases be eradicated? A report on the International Conference on the Eradication of Infectious Diseases. Rev Infect Dis 1982;4:913- 84.

  24. Hopkins DR. Beyond smallpox eradication. In: Mandl PE, ed. Assignment Children. Vol 69/72. Geneva: UNICEF, 1985.

  25. Duke BOL. Onchocerciasis (river blindness) -- can it be eradicated? Parasitology Today 1990;6:82-4.

  26. Schantz PM, Cruz M, Sarti E, Pawlowski ZS. The potential eradicability of taeniasis and cysticercosis. Bull Pan Am Hlth Org (in press).

  27. Hopkins DR, Ruiz-Tiben E. Surveillance for dracunculiasis, 1981-1991. MMWR 1992;41(No. SS-1):1-13.

  28. Hinman AR, Foege WH, de Quadros CA, et al. The case for global eradication of polio. Bull World Health Organ 1987;65:835-40.

  29. WHO. Lymphatic filariasis: the disease and its control -- sixth report of the WHO Expert Committee on Filariasis. Geneva: World Health Organization, 1992. (Technical report series no. 821).

  30. CDC. Mumps prevention. MMWR 1989;38:388-92,397-400.

  31. Hethcote HW. Rubella. Biomathematics 1989;18:212-34.

  32. Maynard JE, Kane MA, Hadler SC. Global control of hepatitis B through vaccination. Rev Infect Dis 1989;11(suppl 3):574-8.

  33. Dunn JT. Iodine deficiency -- the next target for elimination? N Engl J Med 1992;326:267-8.

  34. WHO. Neonatal Tetanus Consensus Group Meeting. Geneva: 1990. (Report No. EPI/MCH/NNT/90/WP.4).

  35. WHO. World Health Organization Expert Committee on Rabies. Technical Report Series #824. Geneva: World Health Organization, 1992.

  36. Schachter J, Dawson CR. Epidemiology of trachoma predicts more blindness in the future. Scand J Infect Dis Suppl 1990;69:55-62.

  37. Meheus A, Antal GM. The endemic treponematoses: not yet eradicated. World Health Stat Q 1992;45:228-37.

  38. Pawlowski ZS. Strategies for the control of ascariasis. Ann Soc Belg Med Trop 1984;64:125-34.

  39. Barua D, Greenough WB III. Cholera. New York: Plenum Scientific Publishing, 1991.

  40. Kriz B, Teply V, Pecenka J, et al. Immunologic surveys of diphtheric antitoxic antibodies in some African and Asian countries. J Hyg Epidemiol Microbiol Immunol 1980;24:42-62.

  41. Pawlowski ZS, Schad GA, Stott GJ. Hookworm infection and anemia. Geneva: World Health Organization, 1991.

  42. WHO. Epidemiology of leprosy in relation to control: report of a WHO study group. Geneva: World Health Organization, 1985. (Technical report series no. 716).

  43. Adcock LM, Bissey JD, Feigin RD. A new look at measles. Infect Dis Clin N Amer 1992;6:133-48.

  44. Cherry JD. The epidemiology of pertussis and pertussis immunization in the UK and the US. Curr Probl Pediatr 1984;14:1-78.

  45. Anonymous. Puzzling diversity of rotaviruses. Lancet 1990;335:573-5.

  46. Mahmoud AAF, Wahab MFA. Schistosomiasis. In: Warren KF, Mahmoud AAF, eds. Tropical and geographic medicine. New York: McGraw-Hill, 1990.

  47. Styblo K. Overview and epidemiologic assessment of the current global tuberculosis situation. Rev Infect Dis 1989;11(suppl):339- 46.

  48. Monath TP, Nasidi A. Should yellow fever vaccine be included in the expanded program of immunization in Africa? A cost-effectiveness analysis for Nigeria. Am J Trop Med Hyg 1993;48:274-99.

  49. Martinez-Palomo A, Ruiz-Palacios G. Amebiasis. In: Warren KS, Mahmoud AAF, eds. Tropical and geographical medicine. 2nd ed. New York: McGraw-Hill, 1990:327-44.

  50. Benenson AS, ed. Control of communicable diseases in man. 14th ed. Washington, DC: American Public Health Association, 1985; pp. 51-3.

  51. Benenson AS, ed. Control of communicable diseases in man. 14th ed. Washington, DC: American Public Health Association, 1985; pp. 81-2.

  52. Benenson AS, ed. Control of communicable diseases in man. 14th ed. Washington, DC: American Public Health Association, 1985; pp. 132-4.

  53. WHO. Control of Chagas' disease. Geneva: World Health Organization, 1991. Technical report series no. 81.

  54. Gershon AA, ed. The First International Conference on the Varicella-Zoster Viruses. J Infect Dis 1992;166(suppl 1):51-68.

* The summaries were prepared by the project director, based on the working papers presented to the Task Force. The original authors have not reviewed these summaries. Incidence data for several diseases have been updated. A single reference is provided for each summary as a suggestion for further reading. 

** The full text of the World Health Assembly resolutions regarding disease eradication is available on request to the World Health Organization.

APPENDIX_1 Table_A1
Table_1
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TABLE 1. Criteria for assessing eradicability of diseases and conditions
======================================================================================
 Scientific Feasibility

 . Epidemiologic vulnerability (e.g., existence of nonhuman reservoir; ease of
   spread; natural cyclical decline in prevalence; naturally induced immunity;
   ease of diagnosis; and duration of any relapse potential)

 . Effective, practical intervention available (e.g., vaccine or other primary pre-
   ventive, curative treatment, and means of eliminating vector). Ideally,
   intervention should be effective, safe, inexpensive, long-lasting, and easily de-
   ployed.

 . Demonstrated feasibility of elimination (e.g., documented elimination from
   island or other geographic unit)

 Political Will/Popular Support

 . Perceived burden of the disease (e.g., extent, deaths, other effects; true bur-
   den may not be perceived; the reverse of benefits expected to accrue from
   eradication; relevance to rich and poor countries).

 . Expected cost of eradication (especially in relation to perceived burden from
   the disease).

 . Synergy of eradication efforts with other interventions (e.g., potential for
   added benefits or savings or spin-off effects)

 . Necessity for eradication rather than control
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Table_2
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TABLE 2. Milestones in disease eradication
===============================================================================
1888       Charles V. Chapin urges eradication of tuberculosis (TB).
1892       Contagious pleuropneumonia of cattle declared eradicated from
           United States after 5-year campaign costing $5 million, begun in
           1884.
1896       Rabies eradicated from England.
1901       Gen. William C. Gorgas eradicates yellow fever from Havana.
1907       Rockefeller Foundation establishes Sanitary Commission for
           Eradication of Hookworm Disease in the United States; eventually
           stimulates projects in 52 countries.
1915       Rockefeller Foundation establishes Yellow Fever Commission to
           eradicate that disease, under leadership of Gorgas. Fear of im-
           porting yellow fever to Asia via Panama Canal.
1917       Decision to eradicate bovine TB from United States.
1922       Rockefeller Foundation's hookworm campaign begins phasing
           out after evaluation shows little impact on transmission.
1923       Yellow fever reappears in Brazil after nearly a year's absence.
1928-1929  Other outbreaks of yellow fever in Brazil, including in Rio de
           Janeiro.
1930       Anopheles gambiae mosquito discovered in Brazil.
1933       Yellow fever realized to be widespread in South American forests;
           search for hidden breeding sites of A. aegypti vector reveals its
           disappearance from cities of coastal Brazil.
1934       Eradication of A. aegypti in Brazil is proposed.
1937       Wade Hampton Frost reports human TB is being eradicated in the
           United States and other countries.
1937-1938  Large fatal malaria epidemics associated with A. gambiae in
           Brazil.
1939-1941  A. gambiae eradicated from Brazil.
1943       Bolivia is first country to proclaim eradication of A. aegypti.
1943-1945  A. gambiae eradicated from Egypt.
1947       Pan American Health Organization (PAHO) adopts proposal for
           eradication of A. aegypti from Americas.
1950       Pan American Sanitary Conference approves goal of continental
           smallpox eradication and continental yaws eradication; begins
           collaboration with national malaria eradication programs.
1951       Malaria eradicated from Sardinia.
1954       Yaws eradication goal declared by World Health Organization
           (WHO).
1955       Eighth World Health Assembly (WHA) adopts goal of global ma-
           laria eradication.
1958       11th WHA adopts goal of global smallpox eradication.
1966       19th WHA adopts goal of intensified global smallpox eradication
           by 1976.
1969       WHO officially changes malaria eradication policy back to malaria
           control, after expenditure of estimated $1.4 billion during 1955-
           1965.
1970       Smallpox is eradicated from the Americas.
1975       Europe free of malaria for first time in history.
1977       Smallpox eradicated worldwide.
1978       U.S. goal of measles elimination by 1982 is announced.
1980       Smallpox eradication declared by WHO; International Conference
           on Eradication of Infectious Diseases held in Washington; India
           begins national dracunculiasis eradication program.
1985       PAHO sets goal of poliomyelitis elimination from Americas by
           1990; Europe sets goal of measles elimination by 2000.
1986       39th WHA declares goal of dracunculiasis elimination.
1988       41st WHA declares goal of global poliomyelitis eradication by
           2000; African Region of WHO sets goal of dracunculiasis elimina-
           tion from Africa by 1995.
1989       International Task Force for Disease Eradication meets for first
           time.
1990       WHO meeting on criteria and procedures for certification of
           dracunculiasis elimination; PAHO's Executive Committee begins
           considering other potential candidates for elimination in the
           Americas by 2000.
1991       44th WHA declares goal of global dracunculiasis eradication by
           1995; last case of indigenous poliomyelitis in the Americas occurs
           in Peru.
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Table_3
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TABLE 3. Diseases considered as candidates for global eradication by the International
Task Force for Disease Eradication
=======================================================================================================
                      Current annual toll
Disease                    worldwide         Chief obstacles to eradication    Conclusion
-----------------------------------------------------------------------------------------------------

Diseases targeted for eradication

Dracunculiasis        <2 million persons     Lack of public and political      Eradicable
(Guinea worm          infected; few deaths   awareness; inadequate
disease)                                     funding

Poliomyelitis         100,000 cases of       No insurmountable technical       Eradicable
                      paralytic disease;     obstacles; increased
                      10,000 deaths          national/international
                                             commitment needed

Lymphatic             80 million cases       Need better tools for             Potentially eradicable
filariasis                                   monitoring infection

Mumps                 Unknown                Lack of data on impact in         Potentially eradicable
                                             developing countries;
                                             difficult diagnosis

Rubella               Unknown                Lack of data on impact in         Potentially eradicable
                                             developing countries;
                                             difficult diagnosis

Taeniasis/            50 million cases;      Need simpler diagnostics for      Potentially eradicable
cysticercosis         50,000 deaths          humans and pigs
(pork tapeworm)

Diseases/conditions of which some aspect could be eliminated

Hepatitis B           250,000 deaths         Carrier state, infections in      Not now eradicable,
                                             utero not preventable; need       but could eliminate
                                             routine infant vaccination        transmission over
                                                                               several decades

Iodine deficiency     Unknown                Inadequate surveillance, lack     Could eliminate
disorders                                    of environmental sources of       iodine deficiency
                                             iodine                            disorders

Neonatal tetanus      560,000 deaths         Inexhaustible environmental       Not now eradicable,
                                             reservoir                         but could prevent
                                                                               transmission

Onchocerciasis        18 million cases;      High cost of vector control;      Could eliminate
(river blindness)     340,000 blind          no therapy to kill adult          associated blindness
                                             worms; restrictions in mass
                                             use of ivermectin

Rabies                52,000 deaths          No effective way to deliver       Could eliminate urban
                                             vaccine to wild animals that      rabies
                                             carry the disease

Trachoma              500 million cases;     Linked to poverty; ubiquitous     Could eliminate
                      6-8 million blind      microbe                           blindness

Yaws and other        2.5 million cases      Political and financial inertia   Could interrupt
endemic                                                                        transmission *
treponematoses

Diseases that are not eradicable now

Ascariasis            1 billion infected;    Eggs viable in soil for years;    Not now eradicable
(roundworm)           20,000 deaths          laborious diagnosis;
                                             widespread

Cholera               Unknown                Environmental reservoirs;         Not now eradicable
                                             strain differences

Diphtheria            Unknown                Difficult diagnosis;              Not now eradicable
                                             multiple-dose vaccine

Hookworm              900 million            Laborious diagnosis; adult        Not now eradicable
disease               infected; 60,000       worms may live 5 years;
                      deaths                 widespread

Leprosy               11-12 million cases    Need for improved                 Not now eradicable
(Hansen's                                    diagnostic tests and
disease)                                     chemotherapy; social stigma;
                                             potential reservoir in
                                             armadillos

Measles               Almost 1 million       Lack of suitably effective        Not now eradicable
                      deaths, mostly         vaccine for young infants;
                      among children         cost; public misconception of
                                             seriousness

Pertussis             40 million cases;      High infectiousness; early        Not now eradicable
(whooping             400,000 deaths         infections; multiple-dose
cough)                                       vaccine

Rotaviral enteritis   80 million cases;      Inadequate vaccine                Not now eradicable
                      870,000 deaths

Schistosomiasis       200 million infected   Reservoir hosts; increased        Not now eradicable
(bilharziasis)                               snail-breeding sites

Tuberculosis          8-10 million new       Need for improved                 Not now eradicable
                      cases; 2-3 million     diagnostic tests,
                      deaths                 chemotherapy and vaccine;
                                             wider application of current
                                             therapy

Yellow fever          >10,000 deaths         Sylvatic reservoir; heat-labile   Not now eradicable
                                             vaccine

Diseases that are not eradicable

Amebiasis             500 million cases;     Asymptomatic infections;          Not eradicable
                      40,000-110,000         difficult diagnosis, treatment
                      deaths

Bartonellosis         Unknown                Asymptomatic infections;          Not eradicable
                                             difficult diagnosis, treatment

Clonorchiasis         20 million cases in    Animal reservoir;                 Not eradicable
                      China alone            asymptomatic infections;
                                             carrier state

Enterobiasis          Unknown                Widespread; mild disease          Not eradicable

American              15-20 million          Difficult diagnosis,              Not eradicable
trypanosomiasis       infected               treatment; animal reservoirs
(Chagas' disease)

Varicella zoster      3 million cases in     Latency of virus; inadequate      Not eradicable
                      USA alone              vaccine
-----------------------------------------------------------------------------------------------------
* Because persons may be infected for decades and the organisms cannot be distinguished
  from those that cause venereal syphilis, elimination of transmission -- not eradication -- is the
  goal.
=======================================================================================================


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Table_4
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TABLE 4. Diseases targeted for eradication/elimination
========================================================================
 1990       Poliomyelitis elimination in Americas {achieved in 1991}
 1991       Dracunculiasis elimination in Pakistan {achieved in 1993}
 1995       Dracunculiasis eradication
            Poliomyelitis elimination in Europe, Western Pacific
            Measles elimination in English-speaking Caribbean
            Neonatal tetanus elimination
 2000       Poliomyelitis eradication
            Measles elimination in Europe
            Leprosy elimination (defined as <1 case/10,000 population)
 2007       Elimination of onchocerciasis in the Americas
========================================================================


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Table_A1
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APPENDIX 1. Diseases screened for potential eradicability by the International Task Force for Disease Eradication *
================================================================================================================================================
                                                          Epidemiologic
Disease/condition               Extent of problem         vulnerability                 Intervention(s) available   Political will   Comment
----------------------------------------------------------------------------------------------------------------------------------------------
Actinomycosis                   Infrequent;               Found in normal flora of      Surgery, prolonged               None          --
                                worldwide                 oral cavity                   chemotherapy

Acquired                        Spreading                 Sexual transmission; no       Health education,                High          --
immunodeficiency                worldwide; 200,000        natural immunity;             condoms; mitigate
syndrome                        deaths/year; 6-8          difficult diagnosis           infection with
                                million infected                                        azidothymidine (AZT)

Angiostrongyliasis              Infrequent; Pacific       Reservoir in snails,          Rat control, cook                None          --
                                islands, Cuba,            slugs, rats                   seafoods
                                E. Africa

Anisakiasis                     Infrequent; Asia, N.      Wide reservoir in marine      Avoid eating                     None          --
                                Europe, Latin             fish and squid; difficult     inadequately cooked
                                America                   diagnosis                     marine fish

Anthrax                         Sporadic,                 Viable spores in soil for     Immunization, antibiotic         Low           --
                                occasionally              years, also on animal         treatment, disinfection
                                epidemic;                 hides; zoonosis
                                worldwide,
                                endemic in parts of
                                Asia, Africa

Arenaviral hemorrhagic          Bolivia, Argentina;       Wild rodent reservoir; no     Rodent control; isolation        None          --
fever                           300-600 cases             specific treatment or         of patient
                                reported/year             vaccine

Arboviral encephalitis          N. America, parts of      Reservoirs unknown or         Mosquito control,           Low; epidemic      --
(eastern equine                 Asia (JE)                 widespread in animals         vaccine for JE, EEE         economic
encephalitis (EEE), western                                                                                         burden
equine encephalitis,
Japanese encephalitis
(JE), St. Louis encephalitis)
(also fever)

Aspergillosis                   Worldwide;                Reservoir in decaying         Treatment difficult              None          --
                                uncommon                  vegetation; spread by
                                                          inhalation of airborne
                                                          spores

Babesiosis                      N. America, Europe,       Rodent or cattle reservoir    Rodent, tick control;            Low           --
                                rare                                                    chemotherapy

Balantidiasis                   Worldwide; low            Reservoir in swine,           Sanitation, chemotherapy         None          --
                                incidence                 feces, possibly others;
                                                          resistant to water
                                                          chlorination

Blastomycosis                   Uncommon; Asia,           Reservoir probably in         Chemotherapy difficult           None          --
                                Africa, N. America        soil; inhaled

Brucellosis                     Worldwide; 200            Reservoir in domestic         Education, milk                  Low           --
                                cases/year reported       and wild animals;             pasteurization;
                                in USA                    serologic diagnosis           chemotherapy

Candidiasis                     Worldwide                 Part of normal human          Treatment difficult              None          --
                                                          flora

Capillariasis                   Philippines;              Possible reservoir in         Avoidance of raw fish            None          --
                                1,500 cases since         aquatic birds; life cycle
                                1963; 10%                 uncertain
                                case-fatality rate

Chancroid                       Worldwide,                Sexual transmission; no       Oral antibiotic treatment        None          --
                                especially tropics        immunity; difficult           for 7-10 days
                                                          diagnosis

Cat-scratch disease             Worldwide;                Reservoir in cats; no         None                             None          --
                                uncommon, usually         specific treatment
                                self-limited

Chlamydial infections           Worldwide;                Sexual transmission;          Health education;                Low           --
(genital)                       common; important         most patients                 antibiotic therapy
                                cause of infertility      asymptomatic; no
                                                          immunity; diagnosis
                                                          difficult

Chromomycosis                   Worldwide; sporadic       Reservoir in wood, soil,      Treatment very difficult         None          --
                                                          decaying vegetation

Coccidioidomycosis              Arid parts of             Reservoir in soil;            Outdoor dust control;            Low           --
                                Americas                  inhalation; most infected     treatment difficult
                                                          persons acquire
                                                          immunity; occupational
                                                          exposure; diagnosis by
                                                          culture and skin test

Cryptococcosis                  Sporadic;                 Reservoir in soil, pigeon     Disinfection (chemical);         None          --
                                worldwide,                droppings; difficult          difficult treatment
                                increased incidence       diagnosis
                                related to AIDS

Cryptosporidiosis               Probably worldwide        Reservoir in cattle, other    Personal hygiene                 None          --
                                                          domestic and wild
                                                          animals; fecal-oral
                                                          transmission; diagnosis
                                                          by fecal smear or
                                                          intestinal biopsy

Cytomegalovirus disease         Common;                   Humans only known             Sanitation, hygiene; no          None          --
                                worldwide; severe         reservoir; many               vaccine or treatment
                                infection in some         inapparent infections;
                                infants; some             direct contact with
                                morbidity in              infected secretions; viral
                                infected adults;          shedding in urine or
                                increased incidence       saliva for years;
                                related to AIDS           diagnosis by viral
                                                          isolation, serology

Dengue fever                    Tropical Asia, W.         Possible monkey               Mosquito control                 Low           --
                                Africa, Caribbean         reservoir; homologous
                                and Central               immunity; dengue
                                America; periodic         hemorrhagic fever
                                epidemics with            associated with Aedes
                                fatalities                aegypti vector; four
                                                          serotypes; diagnosis by
                                                          serology, culture

Campylobacter diarrhea          Causes 5%-14% of          Reservoir in many             Sanitation; oral                 Low           --
                                all diarrhea              animals, including pets;      rehydration, some
                                worldwide; some           diagnosis by stool            antibiotics
                                traveler's diarrhea       isolation

Diphyllobothriasis              N. America, Europe        From inadequately             Praziquantel treatment           None          --
                                                          cooked freshwater fish;
                                                          reservoir also in dogs
                                                          and bears; diagnosis by
                                                          fecal examination

Ebola-Marburg virus             Some parts of             Unknown reservoirs in         Disinfection; quarantine         None          --
                                Africa; often fatal       African animals;
                                                          person-to-person
                                                          transmission

Echinococcosis                  Asia, America,            Diagnosis by                  Hygiene, surgery;                None          --
                                Africa in association     microscopy, x-ray,            destruction or mass
                                with herd dogs            serology; contaminated        chemotherapy of dogs
                                                          hands, food, water; wide
                                                          reservoir in domestic
                                                          and wild animals

Fascioliasis                    Cattle-raising areas      Reservoir in cattle, other    Praziquantel                     None          --
                                of Asia, Americas,        large herbivores; from        chemotherapy, education
                                Europe                    uncooked watercress;
                                                          diagnosis by fecal exam

Fasciolopsiasis                 Southeast Asia            Reservoir in pigs,            Sanitation, education;           None          --
                                                          humans, dogs; from            praziquantel
                                                          uncooked plants;              chemotherapy
                                                          diagnosis by microscopy
                                                          of feces

Giardiasis                      Worldwide cause of        Reservoir in beavers;         Sanitation, hygiene,             None          --
                                chronic diarrhea          large proportion of           water supply;
                                                          infections asymptomatic;      chemotherapy
                                                          diagnosis by stool smear

Gonorrhea                       Common                    No nonhuman reservoir;        Health education;                Low           --
                                worldwide; major          chronic carrier state         condoms; chemotherapy
                                cause of infertility,     possible; sexually            limited by wide
                                abdominal                 transmitted; no natural       resistance to penicillin
                                infections (acute)        immunity; diagnosis by
                                                          microscopy

Herpes simplex                  Both types common         Humans only reservoir;        Condoms; health                  Low           --
                                worldwide                 direct contact, sexual        education; acyclovir
                                                          transmission; long            orally or topically
                                                          latency; microscopic,
                                                          serologic diagnosis

Histoplasmosis                  Almost worldwide;         Reservoir in dust/soil        Disinfection;                    None          --
                                common focal              associated with chickens,     chemotherapy difficult
                                infections, clinical      bats and starlings; not
                                disease uncommon          transmitted person to
                                                          person; diagnosis by
                                                          culture, skin test, or
                                                          microscopy

Hymenolepiasis                  Cosmopolitan;             Possible reservoir in         Hygiene and sanitation;          None          --
                                uncommon cause            mice; infections persist      chemotherapy
                                of disease                for years; many
                                                          asymptomatic infections;
                                                          diagnosis by stool smear

Influenza                       Worldwide; major          Animal reservoir              Partially effective            Moderate        --
                                cause of morbidity        suspected; highly             vaccine;
                                and mortality;            infectious by respiratory     chemoprophylaxis for
                                epidemic potential        route; numerous               type A
                                                          serotypes, shifting;
                                                          type-specific immunity

Lassa Fever                     West and Central          Wild rodent reservoir;        Rodent control;                  Low           --
                                Africa; exportation       natural immunity after        quarantine; disinfection;
                                to Europe, N.             recovery; diagnosis by        plasma and ribavirin
                                America; fatal in         isolation, dangerous
                                epidemics

Legionellosis                   Nearly worldwide          Reservoir in water            Disinfection of water            None          --
                                cause of acute            systems, possibly soil;       systems; antibiotic
                                pneumonia, fever;         no person-to-person           treatment
                                sometimes fatal           transmission; diagnosis
                                                          by isolation or serology

Leishmaniasis (cutaneous,       Extensive sporadic        Extensive wild and            Insecticide control of           Low           --
visceral)                       infection in Old and      domestic animal               sandfly; destroy animal
                                New World;                reservoirs; multiple          reservoirs;
                                estimated 12              strains of parasite;          chemotherapy difficult
                                million cases; over       immunity after healing;
                                400,000 new               diagnosis by
                                cases/year; visceral      microscopy, serology, or
                                form sometimes            biopsy
                                fatal

Leptospirosis                   Worldwide                 Extensive reservoirs in       Rodent control; boots            None          --
                                zoonosis; low             wild and domestic             and gloves; avoidance of
                                fatality rate; hazard     animals; many                 contaminated water;
                                in occupations with       serotypes; diagnosis by       limited immunization;
                                animal contact            serology or isolation         weekly
                                                                                        chemoprophylaxis

Listeriosis                     Sporadic,                 Reservoir in infected         Antibiotic treatment             None          --
                                uncommon                  human carriers,
                                infection; rarely fatal   domestic and wild
                                                          animals; diagnosis very
                                                          difficult

Loiasis                         West and Central          Humans only reservoir;        Vector control of fly; fly       None          --
                                Africa; highly            microfilariae in humans       repellents;
                                endemic in some           up to 17 years; no known      chemoprophylaxis;
                                villages                  immunity; diagnosis by        treatment difficult
                                                          microscopy of blood           (diethylcarbamazine);
                                                                                        ivermectin a possibility

Lyme disease                    USA, Europe,              Reservoir in ticks, wild      Vector control; palliative       None          --
                                Australia                 deer, rodents; clinical       treatment
                                                          diagnosis, serology

Lymphocytic                     Uncommon,                 Mice, hamster reservoir;      Sanitation and hygiene           None          --
choriomeningitis                localized infection       asymptomatic infections;
                                                          diagnosis by viral
                                                          isolation, serology

Lymphogranuloma                 Worldwide,                Humans only reservoir;        Condoms; 2 weeks of              None          --
venereum                        especially tropical,      sexually transmitted,         oral antibiotics
                                subtropical               often asyrmptomatic,
                                                          very chronic; diagnosis
                                                          by microscopy, serology

Malaria                         Mainly tropical;          Humans main reservoir;        Chemotherapy                     High        Legacy
                                1-2 million               relapses, asymptomatic        (resistance); vector                         of failed
                                deaths/year               infections; multiple          control (resistance);                        campaign
                                                          strains; diagnosis by         chemoprophylaxis
                                                          microscopy                    (resistance)

Melioidosis                     Asia, Africa,             Reservoir in some soil        Chemotherapy                     None          --
                                Americas;                 and water; various
                                uncommon                  animals; often
                                                          asymptomatic; relapses;
                                                          diagnosis by isolation,
                                                          serology

Meningococcal meningitis        Widespread;               Humans only reservoir;        Vaccines against some            Low           --
(Neisseria meningitidis)        temperate and             asymptomatic carriers;        serotypes; respiratory
                                tropical; epidemic        several serogroups;           isolation; chemotherapy,
                                tendency, especially      microscopic diagnosis         chemoprophylaxis (some
                                in hot, dry regions                                     antibiotic resistance)
                                (Sahel); often fatal

Haemophilus meningitis          Common in USA;            Humans only reservoir;        Antibiotic treatment and         Low           --
                                associated with           diagnosis by isolation or     prophylaxis; vaccine
                                other clinical            serology                      against type B
                                involvement; often
                                fatal; worldwide

Infectious mononucleosis        Common,                   Humans only reservoir;        Disinfection; reduce        Low (vaccine       --
(Epstein-Barr virus {EBV})      worldwide; usually        spread by saliva;             malaria to reduce           would elevate)
                                mild; same agent          convalescent immunity;        incidence of Burkitt's
                                (EBV) associated          difficult clinical            lymphoma
                                with Burkitt's            differential diagnosis;
                                lymphoma,                 laboratoy tests required
                                nasopharyngeal
                                cancer

Nocardiosis                     Worldwide;                Reservoir in soil;            Some patients respond            None          --
                                occasional, chronic       transmitted by                to antibiotic therapy
                                                          inhalation; diagnosis by
                                                          microscopy

Paragonimiasis                  Extensive in Asia,        Reservoirs in domestic        Avoidance of                     None          --
                                also parts of Africa,     and wild carnivores; no       inadequately cooked
                                Latin America;            immunity; diagnosis by        crabs; sanitation
                                chronic effects in        stool examination, chest
                                lung                      x-ray

Pediculosis (body lice)         Worldwide, not fatal      Humans only reservoir;        Health education,                None          --
                                                          spread by direct contact      hygiene; disinfection of
                                                          (including sexual)            clothing, homes; lotion
                                                                                        or powders

Plague                          Focal but                 Extensive wild rodent         Wild rodent and flea           Moderate-       --
                                worldwide                 reservoir; pulmonary          control; killed bacterial        high
                                distribution in wild      form spreads human to         vaccine; quarantine;
                                rodents; high             human; fleas infective        antibiotic treatment
                                fatality rate;            for months; microscopic
                                sporadic in western       diagnosis
                                USA

Pneumonococcal                  Worldwide; often          Humans only reservoir;        Polyvalent vaccine;              Low           --
pneumonia                       fatal in extremely        many asymptomatic             antibiotic therapy
                                old or young              carriers; diagnosis by
                                persons or                microscopy
                                alcoholics

Psittacosis                     Worldwide;                Apparently healthy            Destruction of infected          None          --
                                sporadic human            carriers in birds;            birds; public education;
                                cases                     infection by inhalation;      weeks of antibiotic
                                                          serologic diagnosis           therapy

Q Fever                         Worldwide;                Extensive reservoir in        Vaccine; health                  None          --
                                epidemics rarely          cattle, sheep, goats;         education; disinfection;
                                fatal                     serologic diagnosis           antibiotics

Relapsing fever                 Asia, Africa,             Epidemic if borne by lice,    Personal and                     Low           --
                                Americas; endemic         endemic if by ticks;          environmental vector
                                fatality rates may        tick-borne reservoir in       control; tetracycline
                                be as high as 50%         wild rodents and ticks;       treatment
                                                          infected ticks can live for
                                                          years; limited immunity;
                                                          diagnosis by darkfield
                                                          microscopy

Tick-borne rickettsioses        Americas or other,        Reservoir in ticks, dogs,     Health education, tick           Low           --
(Rocky Mountain spotted         case-fatality rate up     rodents; diagnosis            control, antibiotic therapy
fever)                          to 20%                    difficult, by serology

Salmonellosis                   Worldwide, cause          Wide reservoir in wild        Thorough cooking of              None          --
                                of diarrhea and           and domestic animals,         food; education;
                                sometimes severe          especially raw dairy          antibiotic therapy
                                infections; common        products; numerous
                                                          serotypes; carrier state
                                                          for months

Scabies                         Widespread cause          Humans only reservoir,        Education, topical               None          --
                                of intense skin           transmission by               treatment, isolation
                                infection;                skin-to-skin contact or
                                associated with           via clothing
                                poverty

Shigellosis                     Worldwide;                Humans are main               No commercial vaccine;           None          --
                                common cause of           reservoir, also in primate    water supply, health
                                severe dysentery          colonies; asymptomatic        education, hygiene and
                                and death,                carriers; several             sanitation; oral
                                especially in             serotypes; diagnosis by       rehydration, antibiotics
                                children                  microscope, culture           (resistance occurs)

Strongyloidiasis                Widespread in             Possible reservoir in         Health education,                Low           --
                                tropics and some          dogs as well as humans;       sanitation,
                                temperate areas;          larvae actively penetrate     chemotherapy, shoes
                                autoinfection             skin from fecally
                                possible, potentially     contaminated soil;
                                fatal                     duration of
                                                          communicability up to
                                                          35 years; microscopic
                                                          diagnosis

Syphilis (veneral,              Widespread,               Humans only reservoir;        Single-dose penicillin           Low
congenital)                     especially urban;         diagnosis difficult;          treatment, condoms;
                                >=5% prevalence in        serology; sexual              education; finger-stick
                                pregnant women;           transmission; partial         serology, case-finding
                                congenital                immunity; relapses            and treatment
                                infections severe,
                                fatal, or chronic

Toxocariasis (visceral          Chronic disease of        Reservoir in dogs and         Sanitation and hygiene;          None          --
larval migrans)                 children worldwide;       cats; ingestion of soil       education of pet owners;
                                not common                contaminated by their         chemotherapy poor
                                                          feces; eggs viable in soil
                                                          for months; diagnosis
                                                          very difficult

Toxoplasmosis                   Worldwide;                Wide reservoir in             Sanitation and hygiene;          None          --
                                common infection;         rodents, cats, swine,         education of pet owners;
                                potential fatal           cattle; transmission to       proper cooking of meat;
                                                          humans transplacental,        chemotherapy
                                                          via raw meat, or by
                                                          ingestion of cat feces;
                                                          recovered patients a re
                                                          immune

Trench fever                    Endemic in parts of       Associated with body          Delousing; antibiotic            None          --
                                Europe, Africa,           louse, no other reservoir;    therapy
                                Latin America             diagnosis difficult

Trichinosis                     Worldwide                 Reservoir in mice, rats,      Proper cooking practices,        None          --
                                endemic, sporadic         dogs, wild animals,;          freezing of meat
                                occurrences,              associated with eating
                                potentially fatal         poorly cooked pork, wild
                                                          animal meat

Trichomoniasis                  Prevalent                 Humans only reservoir;        Health education,                None          --
                                worldwide, not fatal      sexual transmission;          condoms; chemotherapy
                                                          often asymptomatic;
                                                          diagnosis by microscopy

Trichuriasis                    Worldwide,                Humans only reservoir;        Sanitation and hygiene;          None          --
                                especially in             microscopic diagnosis         chemotherapy
                                tropics, usually
                                asymptomatic

African trypanosomiasis         Only in tropical          Reservoir in wild game        Chemotherapy                     Low-          --
                                Africa; estimated         for one of the two types;     improved; brush clearing       moderate
                                25,000 cases and          no immunity; diagnosis        for vector control; locally
                                20,000 deaths per         by microscopic exam of        made tsetse traps;
                                year; major               blood or spinal fluid;        residual insecticides
                                problem for               serologic diagnosis
                                domestic livestock        improved

Tularemia                       N. America, Europe,       Extensive reservoir in        Gloves; live vaccine,            None          --
                                USSR, Japan;              wild animals;                 antibiotic therapy,
                                contact with wild         transmission by direct        education
                                animals                   contact, inhalation, or
                                                          tick bite; immunity;
                                                          diagnosis by serology or
                                                          culture

Typhoid fever                   Worldwide; fatality       Human asymptomatic            Hygiene, water,                  None          --
                                rate up to 10%,           carrier state;                sanitation; antibiotic
                                25,000 deaths/year        drug-resistant strains;       therapy; partly effective
                                                          diagnosis by blood            vaccine
                                                          culture

Epidemic louse-borne            Mountainous cooler        Zoonosis of flying            Chemical delousing,              None          --
typhus                          regions of Latin          squirrels in USA;             personal hygiene;
                                America, Africa,          asymptomatic cases;           immunization, antibiotic
                                Asia; case-fatality       relapses after years;         therapy
                                rate 10%-40%              difficult serologic
                                                          diagnosis

Murine typhus                   Worldwide; milder         Reservoir in rats; other      Rat, mouse control;              None          --
                                than louse-borne          wild or domestic animals      insecticides against flea
                                typhus; in                may be infected               vectors, antibiotics
                                association with
                                mice
----------------------------------------------------------------------------------------------------------------------------------------------
* To determine which diseases could qualify for further consideration by the International Task Force for Disease Eradication (ITFDE), these
  draft criteria were used to screen 94 infectious diseases listed in the 14th edition of Control of Communicable Diseases in Man (Benenson
  AS, ed. Washington, DC; American Public Health Association, 1985). The preliminary proposed disposition is indicated in the last column
  of the table under "Comment;" a line (--) means the disease was deemed unsuitable for further consideratinn by the ITFDE. Note that
  diseases discussed in the text are not listed here.
================================================================================================================================================

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