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Summary of Notifiable Diseases --- United States, 2003
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Division of Public Health Surveillance and Informatics
The Summary of Notifiable Diseases --- United States, 2003 contains the official statistics, in tabular and graphic form, for the reported occurrence of nationally notifiable diseases in the United States for 2003. Unless otherwise noted, the data are final totals for 2003 reported as of June 30, 2004. These statistics are collected and compiled from reports sent by state health departments to the National Notifiable Diseases Surveillance System (NNDSS), which is operated by CDC in collaboration with the Council of State and Territorial Epidemiologists (CSTE). The Summary is available at http://www.cdc.gov/mmwr/summary.html. This site also includes publications from past years.
The Highlights section presents noteworthy epidemiologic and prevention information for 2003 for selected diseases and additional information to aid in the interpretation of surveillance and disease-trend data. Part 1 contains tables showing incidence data for the nationally notifiable diseases during 2003.* The tables provide the number of cases reported to CDC for 2003, as well as the distribution of cases by month, geographic location, and the patient's demographic characteristics (age, sex, race, and ethnicity). Nationally notifiable diseases that are reportable in <40 states do not appear in these tables. Part 2 contains graphs and maps that depict summary data for certain notifiable diseases described in tabular form in Part 1. Part 3 contains tables that list the number of cases of notifiable diseases reported to CDC since 1970. This section also includes a table enumerating deaths associated with specified notifiable diseases reported to CDC's National Center for Health Statistics (NCHS), during 1996--2001. The Selected Reading section presents general and disease-specific references for notifiable infectious diseases. These references provide additional information on surveillance and epidemiologic concerns, diagnostic concerns, and disease control activities.
The infectious diseases designated as notifiable at the national level during 2003 are listed on page 3. A notifiable disease is one for which regular, frequent, and timely information regarding individual cases is considered necessary for the prevention and control of the disease. This section briefly summarizes the history of the reporting of nationally notifiable diseases in the United States.
In 1878, Congress authorized the U.S. Marine Hospital Service (the forerunner of the Public Health Service [PHS]) to collect morbidity reports regarding cholera, smallpox, plague, and yellow fever from U.S. overseas consuls. The intention was to use this information to institute quarantine measures to prevent the introduction and spread of these diseases into the United States. In 1879, a specific Congressional appropriation was made for the collection and publication of reports of these notifiable diseases. Congress expanded the authority for weekly reporting and publication of these reports in 1893 to include data from states and municipal authorities. To increase the uniformity of the data, Congress enacted a law in 1902 directing the Surgeon General to provide forms for the collection and compilation of data and for the publication of reports at the national level. In 1912, in conjunction with PHS, state and territorial health authorities recommended immediate telegraphic reporting of five infectious diseases and the monthly reporting, by letter, of 10 additional diseases. The first annual summary of The Notifiable Diseases in 1912 included reports of 10 diseases from 19 states, the District of Columbia, and Hawaii. By 1928, all states, the District of Columbia, Hawaii, and Puerto Rico were participating in national reporting of 29 specified diseases. At their annual meeting in 1950, state and territorial health officers authorized CSTE to determine which diseases should be reported to PHS. In 1961, CDC assumed responsibility for collecting and publishing data concerning nationally notifiable diseases.
The list of nationally notifiable diseases is revised periodically. For example, a disease might be added to the list as a new pathogen emerges, or a disease might be deleted as its incidence declines. Public health officials at state health departments and CDC continue to collaborate in determining which diseases should be nationally notifiable. CSTE, with input from CDC, makes recommendations annually for additions and deletions. Although disease reporting is mandated by legislation or regulation at the state and local levels, state reporting to CDC is voluntary. Thus, the list of diseases considered notifiable varies slightly by state. All states report the internationally quarantinable diseases (i.e., cholera, plague, and yellow fever) in compliance with the World Health Organization's International Health Regulations.
* Because no cases of anthrax, Powassan encephalitis/meningitis, western equine encephalitis, paralytic poliomyelitis, or yellow fever were reported in the United States during 2003, these diseases do not appear in the tables in Part I. For certain other nationally notifiable diseases, incidence data were reported to CDC but are not included in the tables or graphs of this Summary. Data on chronic hepatitis B and hepatitis C virus infection (past or present) are undergoing data-quality review. Data on ehrlichiosis attributable to other or unspecified agents are being withheld from publication pending the outcome of discussions about the reclassification of certain Ehrlichia species, which will probably affect how data are reported in this category. Data on human immunodeficiency virus (HIV) infections are not included because HIV infection (not acquired immunodeficiency syndrome [AIDS]) reporting has been implemented on different dates and by using different methods than for AIDS case reporting; however, these data are summarized in the Highlights section.
In 1999, mortality data began to be coded according to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision. Comparability ratios provided by NCHS were used to bridge the mortality data for 1996--1998 (deaths coded by using the International Classification of Diseases, Ninth Revision) and 1999--2001.
Provisional data concerning the reported occurrence of notifiable diseases are published weekly in the MMWR. After each reporting year, staff in state health departments finalize reports of cases for that year with local or county health departments and reconcile the data with reports previously sent to CDC throughout the year. These data are compiled in final form in the Summary.
Notifiable disease reports are the authoritative and archival counts of cases. They must be approved by the appropriate epidemiologist from each submitting state or territory before being published in the Summary. Data published in MMWR Surveillance Summaries or other surveillance reports produced by CDC programs might not agree exactly with data reported in the annual Summary because of differences in the timing of reports, the source of the data, or surveillance methodology.
Data in the Summary were derived primarily from reports transmitted to the Division of Public Health Surveillance and Informatics, Epidemiology Program Office, CDC, from health departments in the 50 states, five territories, New York City, and the District of Columbia. More information regarding notifiable diseases, including case definitions for these conditions, is available at http://www.cdc.gov/epo/dphsi/phs.htm. Policies for reporting notifiable disease cases can vary by disease or reporting jurisdiction.
Final data for certain diseases are derived from the surveillance records of the following CDC programs. Requests for further information regarding these data should be directed to the appropriate program.
National Center for Health Statistics (NCHS)
National Center for Infectious Diseases (NCID)
National Center for HIV, STD, and TB Prevention (NCHSTP)
National Immunization Program (NIP)
Disease totals for the United States, unless otherwise stated, do not include data for American Samoa, Guam, Puerto Rico, the U.S. Virgin Islands, or the Commonwealth of the Northern Mariana Islands.
Population estimates for the states are derived from CDC's National Center for Health Statistics (NCHS) census populations with bridged race categories, vintage 2003 postcensal series by year, county, age, sex, race, and Hispanic origin for July 1, 2000--July 1, 2003 (http://www.cdc.gov/nchs/about/major/dvs/popbridge/popbridge.htm). For sexually transmitted diseases, population estimates are derived from the vintage 2002 postcensal series by year, county, age, sex, race, and Hispanic origin for July 1, 2000--July 1, 2002. The choice of population denominators for incidence rates reported in the MMWR is based on 1) the availability of census population data at the time of preparation for publication and 2) the desire for consistent use of the same population data to compute incidence rates reported by various CDC programs. Incidence rate in the Summary is calculated as the number of reported cases for each disease or condition divided by either the U.S. resident population for the specified demographic population or the total U.S. residential population, multiplied by 100,000. When a nationally notifiable disease is associated with a specific age restriction, the same age restriction is applied to the population in the denominator of the incidence calculation. In addition, population data from states in which the disease or condition was not notifiable or was not available were excluded from incidence calculations.
Incidence data in the Summary are presented by the date of report to CDC as determined by the MMWR week and year assigned by the state or territorial health department. In addition, data in the Summary are reported by the state in which the patient resided at the time of diagnosis. For many of the nationally notifiable infectious diseases, surveillance data are independently reported to various CDC programs. Thus, surveillance data reported by other CDC programs might vary from data reported in the Summary because of differences in 1) the date used to aggregate data (e.g., date of report or date of disease occurrence), 2) the timing of reports, 3) the source of the data, 4) surveillance case definitions, and 5) policies regarding case jurisdiction (i.e., which state should report the case to CDC).
The data reported in the Summary are useful for analyzing disease trends and determining relative disease burdens. However, these data must be interpreted in light of reporting practices. Disease reporting is likely incomplete, and completeness might vary depending on the disease. The degree of completeness of data reporting might be influenced by the diagnostic facilities available; control measures in effect; public awareness of a specific disease; and interests, resources, and priorities of state and local officials responsible for disease control and public health surveillance. Finally, factors such as changes in methods for public health surveillance, introduction of new diagnostic tests, or discovery of new disease entities can cause changes in disease reporting that are independent of the true incidence of disease.
Public health surveillance data are published for selected racial and ethnic populations because these variables can be risk markers for certain notifiable diseases. Race and ethnicity data also can be used to highlight populations for focused prevention efforts. However, caution must be used when drawing conclusions from reported race and ethnicity data. Different racial/ethnic populations might have different patterns of access to health care, potentially resulting in data that are not representative of actual disease incidence among specific racial/ethnic populations. Surveillance data reported to NNDSS are in either individual case-specific form or summary form (i.e., aggregated data for a group of cases). Summary data often lack demographic information (e.g., race); therefore, the demographic-specific incidence rates presented in the Summary might be underestimated.
In addition, not all race and ethnicity data are collected uniformly for all diseases. For example, certain disease programs collect data on race and ethnicity by using one or two variables, based on the 1977 standards for collecting such data issued by the Office of Management and the Budget (OMB). However, beginning in 2003, certain CDC programs, including the tuberculosis program, implemented OMB's 1997 revised standards for collecting such data; these programs collect data on multiple races per person by using multiple race variables. Additionally, although the recommended standard for classifying a person's race or ethnicity is based on self-reporting, this procedure might not always be followed.
Highlights for 2003
Below are summary highlights for certain national notifiable diseases. Highlights are intended to assist in the interpretation of major occurrences that affect disease incidence or surveillance trends (e.g., outbreaks, vaccine licensure, or policy changes).
Since 1981, confidential name-based AIDS surveillance has been the cornerstone of national, state, and local efforts to monitor the scope and impact of the HIV epidemic. The data have many uses, including developing policy to help prevent and control AIDS. However, because of the introduction of therapies that effectively slow the progression of the infection, AIDS data no longer adequately represent the populations affected by the epidemic. By providing a window into the epidemic at an earlier stage, HIV data, combined with AIDS data, better represent the overall impact. As of the end of 2003, a total of 40 areas (35 states, Puerto Rico and four U.S. territories) had implemented confidential name-based HIV reporting. These 40 areas have integrated name-based HIV surveillance into their AIDS surveillance systems, whereas other jurisdictions have used other methods for reporting cases of HIV infection. Under no configuration are names or other personal identifying information collected at the national level.
During 1998--1999, declines in AIDS rates began to level. The number of reported cases in 2003 was essentially the same as the number in 1999. This trend follows a period of sharp declines in reported cases after 1996, when highly effective antiretroviral therapies were introduced. At the end of 2003, an estimated 405,926 persons were living with AIDS. After a dramatic decrease in the number of deaths among persons with AIDS during the late 1990s, the rate of decrease flattened through 2003. The number of deaths among persons with AIDS decreased 65% during 1995--1999. During 1999--2003, the number of deaths reported annually decreased 3%.
By 2003, the National Brucellosis Eradication Program had nearly eliminated Brucella abortus infection from U.S. cattle herds. The risk of contracting brucellosis through occupational exposure to livestock in the United States or consumption of domestically produced dairy products therefore is minimal. Consumption of unpasteurized dairy products from outside the United States continues to pose a risk of infection with B. abortus or B. melitensis. The majority of U.S. cases of brucellosis occur among returned travelers or recent immigrants from areas in which Brucella species are endemic. Hunters exposed to infected wildlife might also be at increased risk for infection. Laboratory personnel working with Brucella species should follow recommended biosafety precautions. Brucella species are considered category-B biologic threat agents.
Chlamydia trachomatis, Genital Infection
During 2003, a total of 877,478 cases of genital chlamydial infection were reported. Rates were the highest since voluntary case reporting began in the mid-1980s and the highest since genital chlamydial infection became a nationally notifiable disease in 1995 (1). This increase is attributable in part to continued expansion of chlamydia screening programs and increased use of more sensitive diagnostic tests for this condition. During 1999--2003, the reported chlamydial infection rate among men increased 58% compared with a 27% increase among women. However, the rate reported among women was more than three times the rate reported among men, reflecting the larger number of women screened and tested for this disease.
During 1995--2003, a total of 68 laboratory-confirmed cases of cholera, all caused by Vibrio cholerae O1, were reported to CDC. Of these infections, 44 (65%) were acquired outside the United States, and six (9%) were acquired through consumption of contaminated seafood harvested in Gulf Coast waters. One patient died (1). Only two laboratory-confirmed cases of cholera were reported to CDC in 2003. Both were caused by Vibrio cholerae O1 and were acquired outside the United States. Both isolates were resistant to furazolidone. Production and sale of the only licensed cholera vaccine in the United States ceased in 2001. Worldwide, fewer (111,575) cases of cholera were reported to the World Health Organization from fewer (45) countries in 2003 than in any year since 1993 (2).
In recent years, Arizona and California have experienced substantial increases in the incidence of coccidioidomycosis. This increase is likely related to demographic and climatic changes. Physicians should maintain a high suspicion for acute coccidioidomycosis, especially among patients with a flu-like illness who live in or have visited areas in which disease is endemic.
One fatal, confirmed case of diphtheria was reported to CDC in 2003 (1). The patient was a Pennsylvania man aged 63 years who had spent 1 week in Haiti and had a sore throat 1 day before returning to Pennsylvania. He reported never having been vaccinated against diphtheria. On day 4 of illness, the patient was hospitalized with stridor and a swollen neck and was intubated. Despite administration of antibiotics, the patient's condition worsened, and on day 8 of illness, an extensive membrane was noted when tracheostomy was performed. Diphtheria antitoxin was administered; polymerase chain reaction testing of a membrane sample was positive for Corynebacterium diphtheriae toxin genes at CDC. After 17 days of illness, cardiac complications ensued, and the patient died. No additional cases or carriers were detected among the patient's traveling companions or among household or hospital contacts.
Enterohemorrhagic Escherichia coli
Escherichia coli O157:H7 has been nationally notifiable since 1994 (1). In 2000, the Council for State and Territorial Epidemiologists passed a resolution in which all Shiga toxin-producing E. coli were made nationally notifiable under the name Enterohemorrhagic E. coli (EHEC); national surveillance for EHEC began in 2001. Surveillance categories for EHEC include 1) EHEC O157:H7; 2) EHEC, serogroup non-O157; and 3) EHEC, not serogrouped. Reported infections with the most well-known pathogen in this group, E. coli O157:H7, increased annually during 1994--1999, to a peak of 4,744 cases. This increase in the number of cases was attributable in part to the increasing ability of laboratories to identify this pathogen. During 1996--2002, incidence of diagnosed infections with E.coli O157:H7 reported by active surveillance through FoodNet did not change substantially, although it decreased in 2003 (2).
During 2003, a total of 3,079 cases of E. coli were reported from 50 states, the District of Columbia, and Puerto Rico. Of these, 2,671 (87%) were classified as EHEC O157:H7; 252 (8%) as EHEC, serogroup non-O157; and 156 (5%) as EHEC, not serogrouped. The majority (54%) of cases were reported during August--November.
Healthy cattle, which harbor the organism as part of the bowel flora, are the main animal reservoir for E. coli O157:H7 and other Shiga-toxin producing E. coli. The majority of reported outbreaks are caused by contaminated food or water. Reported cases of E. coli O157:H7 infection have decreased since 2000, following implementation of U.S. Department of Agriculture measures to reduce contamination of meat through improved processing. Direct transmission from animals and their environments to humans in settings such as petting zoos and other animal exhibits remains a growing public health concern (3,4).
During 2003, a total of 335,104 cases of gonorrhea were reported (1). Gonorrhea rates were slightly lower than rates during 1999--2002. In 2003, for the first time, the reported gonorrhea rate among women (118.8 per 100,000) was greater than that reported for men (113.0 per 100,000). Rates among non-Hispanic black women aged 15--19 years (2,947.8 per 100,000) and non-Hispanic black men aged 20--24 years (2,649.8 per 100,000) remain higher than those for any other racial/ethnic population or age group. Decreased susceptibility to fluoroquinolone antibiotics has also been reported from certain regions (2). In 2003, the prevalence of fluoroquinolone-resistant Neisseria gonorrhoeae infections continued to increase, particularly among men who have sex with men (MSM). Fluoroquinolones are no longer advised for treatment of gonorrhea in Hawaii or California or for infections among MSM (3).
In 2003, a total of 376 cases of invasive Haemophilus influenzae disease among children aged <5 years were reported; 32 (9%) were reported as H. influenzae type b (Hib), 117 (31%) were reported as other serotypes or nontypeable isolates, and 227 (60%) were reported with serotype information unknown or missing. The continued low number of invasive Hib infections among children (from an estimated 20,000 cases annually in the prevaccine era) is a result of the successful delivery of highly effective conjugate Hib vaccines to children, beginning at age 2 months (1,2). Because discrepancies in serotyping results have occurred among laboratories, CDC requests that state health departments obtain and send all invasive H. influenzae isolates from children aged <5 years to CDC for serotype confirmation (3,4).
Hemolytic Uremic Syndrome, Postdiarrheal
Hemolytic uremic syndrome (HUS) is a syndrome defined by the triad of hemolytic anemia, thrombocytopenia, and renal insufficiency. The patients reported in national notifiable diseases surveillance include only those with antecedent diarrheal illness. The most common etiology of HUS in the United States is infection with a Shiga toxin-producing Escherichia coli, principally E. coli O157:H7. However, persons infected with E. coli O157:H7 rarely progress to HUS (1,2). During 2003, a total of 178 cases of HUS were reported from 32 states; of these, 118 (66%) occurred among children aged <10 years.
Hepatitis A vaccine is recommended for persons at increased risk of hepatitis A (e.g., international travelers, men who have sex with men [MSM], injection-drug users [IDUs], and noninjection-drug users) (1) and also for children in states and counties that have historically had consistently elevated rates of hepatitis A (2). Since routine childhood vaccination was recommended in 1996, the overall hepatitis A rate has declined steadily, and in 2003, it was the lowest (2.7 per 100,000) yet recorded, with 7,653 cases reported. The decline in rates has been greater among children and in states where routine childhood vaccination is recommended, suggesting an effect of childhood vaccination.
The dramatic declines in disease rates in the age groups and areas in the United States that have historically accounted for the majority of reported cases have resulted in a shift in the epidemiology of this disease. Hepatitis A rates, which historically were much higher in the western states, are now similar in all regions of the United States, and an increasing proportion of cases occur among adults, particularly those in populations at high risk (e.g., MSM).
Despite declining overall rates, outbreaks continue to occur. In 2003, several foodborne outbreaks were reported, including one in Pennsylvania that accounted for more than 500 cases; the produce implicated in each outbreak was believed to have been contaminated during harvest (3).
In 2003, a total of 7,526 acute hepatitis B cases were reported, representing a 64% decrease since 1990, when 21,102 cases were reported. The steady decline in hepatitis B rates coincides with the implementation of a national strategy to eliminate hepatitis B virus (HBV) (1). The primary elements of this strategy are screening all pregnant women for HBV infection with the provision of postexposure prophylaxis to infants born to infected women, routine vaccination of all infants and children aged <19 years; and vaccination of others at increased risk for hepatitis B (e.g., health-care workers, men who have sex with men [MSM], injection-drug users [IDUs], and household and sex contacts of persons with chronic HBV infection).
In 2003, the rate among children aged <12 years, the cohort born since routine infant vaccination was implemented, was 0.02 per 100,000 population, representing a decline of >98% compared with the equivalent age group in 1990. Rates among adolescents aged 12--19 years have declined 90% since 1990 although the rate of decline among this age group, in contrast to that in the younger age group, has slowed in recent years.
Rates among adults declined 63% during 1990--1999 but have since remained stable. Among adults, a high proportion of cases occur among persons in identified high-risk populations (i.e., IDUs, MSM, and persons with multiple sex partners) indicating a need to strengthen efforts to reach these populations with vaccine.
Monitoring acute hepatitis C rates nationally has been challenging because 1) available serologic tests cannot distinguish acute infection from past or chronic infection, and 2) not all health departments have the resources to determine if a positive laboratory report for hepatitis C virus (HCV) infection represents acute infection. Consequently, the most reliable estimates of acute hepatitis C incidence have historically come from sentinel surveillance. Incidence of hepatitis C has declined >80% since the late 1980s, primarily because of a decrease in the number of cases among injection-drug users, the reasons for which are unknown. The majority of hepatitis C cases continue to occur among persons aged >25 years, with injection-drug use being the most common risk factor for infection.
In recent years, analysis of data on acute, symptomatic hepatitis C collected through the National Notifiable Diseases Surveillance System has yielded results similar to those from sentinel surveillance, indicating that the quality of national surveillance data for acute hepatitis C has improved. Direct reporting of anti-HCV--positive test results by laboratories has increased the completeness of reporting of HCV-infected persons to health departments. The reporting of other available laboratory or clinical data would improve surveillance for hepatitis C by providing information to identify patients with acute disease. Improving the accuracy of hepatitis C surveillance data continues to be important because monitoring hepatitis C incidence trends provides information needed to evaluate the effectiveness of prevention efforts and identify additional opportunities for prevention.
HIV Infection, Adult
By December 2003, all 50 states and the District of Columbia had implemented HIV surveillance systems, including both name-based and nonname-based systems. Since 1999, a total of 33 areas (32 states and the U.S. Virgin Islands) have had laws or regulations requiring name-based confidential reporting for adults/adolescents with confirmed HIV infection, in addition to reporting of persons with AIDS. In 2002, CDC initiated a system to monitor HIV incidence; in 2003, CDC expanded this system and also initiated a national HIV behavioral surveillance system. CDC will assess the implementation and effectiveness of prevention activities through multiple monitoring systems, including use of new performance indicators for state and local health departments and community-based organizations (1).
At the end of 2003, a total of 172,952 adults and adolescents in the 33 areas were living with HIV infection (not AIDS). The prevalence rate of HIV infection (not AIDS) in this group was 128 per 100,000 population (2). In these areas, 2003 was the first complete year of name-based surveillance; data from additional areas will be included in analyses when >1 year of case reports has accrued.
HIV Infection, Pediatric
In the 33 areas (32 states and the U.S. Virgin Islands) that have had laws or regulations since 1999 requiring confidential name-based reporting for children (aged <13 years) with confirmed HIV infection, an estimated 1,687 children were living with HIV infection (not AIDS) at the end of 2003. The prevalence rate of HIV infection (not AIDS) in this group was 5.6 per 100,000 population (1).
Listeriosis is a severe but relatively uncommon infection caused by Listeria monocytogenes; it was made a nationally notifiable disease in 2000. Listeriosis is primarily foodborne and occurs most frequently among persons who are older, pregnant, or immunocompromised. During 2003, a total of 696 cases of listeriosis were reported from 46 states and the District of Columbia; the majority (57%) of cases occurred among persons aged >60 years. Incidence was highest (1.52 per 100,000 population) among infants aged <1 year, probably reflecting perinatal transmission from mothers who were infected during pregnancy by ingesting contaminated food.
Molecular subtyping of L. monocytogenes isolates and sharing of that information through PulseNet has enhanced the ability of public health officials to detect and investigate outbreaks of listeriosis. Recent outbreaks have been linked to ready-to-eat meat (1) and unpasteurized cheese (2). In 2003, incidence of listeriosis as reported to FoodNet active surveillance was 0.33 per 100,000 population (3). In January 2001, the Food and Drug Administration (FDA), CDC, and the U.S. Department of Agriculture (USDA) released a national Listeria Action Plan to help guide control efforts by industry, regulators, and public health officials (4). In November 2003, FDA and CDC updated their components of the Action Plan (5). Also in 2003, USDA issued new regulations aimed at further reducing L. monocytogenes contamination of ready-to-eat meat and poultry products (6).
A total of 21,273 cases of Lyme disease were reported in 2003, approximately 10% fewer cases than were reported in 2002. As in previous years, >90% of cases were reported from the northeastern and north-central United States. The number of Lyme disease cases reported for Pennsylvania in 2003 included 4,722 confirmed cases and 1,008 suspected cases. In contrast, the number of suspected Lyme disease cases reported annually for Pennsylvania during 2000--2002 ranged from two to 11 cases. The increase in the number of suspected cases is attributable to changes in reporting practices.
The only Lyme disease vaccine licensed in the United States (LYMErix®) was removed from the market in February 2002, reportedly because of poor sales. Nevertheless, new prevention tools and techniques are becoming available. Recent studies indicate that peridomestic tick exposure can be reduced substantially through simple landscaping changes, and bait boxes that deliver rodent-targeted acaricide are now available through certain pest control operators. Other products under development include devices for reducing ticks on deer and naturally occurring fungi that kill ticks on vegetation.
A total of 56 confirmed measles cases, two of them fatal, were reported during 2003 by 15 states. Of the 56 cases, 24 were internationally imported, and 19 resulted from exposure to persons with imported infections. In two other cases, virologic evidence indicated an imported source. The sources for the remaining 11 cases were classified as unknown because no link to importation was detected. Three outbreaks occurred in 2003 (size range: 3--12 cases) (1,2). The 12-case outbreak was in Hawaii and included persons aged 3 months--21 years; this outbreak began simultaneously with a measles outbreak in the Republic of the Marshall Islands, which resulted in 826 cases and three deaths (3).
During 2003, a total of 11,647 cases of pertussis were reported (incidence: 4.0 per 100,000 population), the highest number of reported cases since 1964. Of the cases for which age was reported, 1,982 (17%) occurred among infants aged <6 months, who were too young to have received the first 3 of the 5 doses of diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccine recommended by age 6 years. This age group had the highest reported incidence (103.1 per 100,000 population). Among the other pertussis cases, 235 occurred among children aged 6--11 months (12.2 per 100,000); 1,138 among children aged 1--4 years (7.5 per 100,000); 852 among children aged 5--9 years (4.4 per 100,000); 4,540 among persons aged 10--19 years (11.1 per 100,000); and 2,854 among persons aged >20 years (1.4 per 100,000).
Pertussis continues to cause morbidity in the United States despite high coverage levels for childhood pertussis vaccine. The incidence of reported pertussis has increased from 2.5 per 100,000 population in 1993 to 4.0 per 100,000 in 2003. How much of this increase is caused by increased recognition and better reporting of cases is unclear (1,2). Although infants have the highest morbidity associated with pertussis (during the 1990s, approximately 18,500 cases were reported among infants, of whom 67% were hospitalized ), adolescents now account for the majority of reported cases. Adolescents and adults can become susceptible to disease when vaccine-induced immunity wanes, approximately 5--10 years after pertussis vaccination (2).
The actual number of pertussis cases (especially among adolescents and adults) continues to be substantially underreported because the pertussis cough illness resembles other conditions, infected persons might not seek medical care, and availability of reliable diagnostic tests is limited. Culture for Bordetella pertussis is highly specific but has low sensitivity. Polymerase chain reaction is not standardized, and its use has led to overdiagnosis of pertussis during certain outbreaks (4). New strategies are needed to reduce the burden of pertussis disease in the United States; pertussis vaccines for adolescents and adults are under review by the Food and Drug Administration.
During 2003, a total of 43,657 cases of salmonellosis were reported, of which 17,608 (40%) occurred among children aged <15 years. As in previous years, the majority (67%) of reported cases occurred during July--October. Salmonella isolates are reported by serotype through the Public Health Laboratory Information System. Two serotypes, S. enterica serotype Typhimurium and S. enterica serotype Enteritidis, have ranked as the two most frequent reported isolates since 1993 (1). A substantial proportion of S. enterica serotype Typhimurium and S. enterica serotype Newport isolates are resistant to multiple drugs; national surveillance of S. enterica serotype Typhimurium strains conducted in 2002 indicated that 40% were resistant to one or more drugs and that 34% had a five-drug resistance pattern characteristic of a single phage type, DT104 (2). During 1998--2002, the proportion of multiple drug-resistant strains of S. enterica serotype Newport increased dramatically; 22% had a five-drug resistance pattern in 2002 compared with 1% in 1998 (2,3).
On March 12, 2003, the World Health Organization (WHO) issued a global alert for severe acute respiratory syndrome (SARS), a potentially fatal new infectious disease that can spread rapidly from person to person and via international air travel. WHO and its partners, including CDC, initiated a rapid, intensive, and coordinated investigative and control effort that led within 2 weeks to the identification of the etiologic agent, SARS-associated coronavirus (SARS-CoV), and to a series of effective containment efforts. By July 2003, when SARS-CoV transmission was brought to an end, >8,000 cases and 780 deaths had been reported to WHO (1). Of the 161 total cases reported from the United States, 134 were classified as suspected; 19 were classified as probable; and eight were laboratory confirmed (2). As of July 1, 2003, SARS-CoV disease was added to the list of nationally notifiable diseases.
Shigella sonnei infections continue to account for >75% of shigellosis cases in the United States (1). Prolonged, multistate outbreaks of S. sonnei infections that are transmitted in child care centers in which maintaining good hygienic conditions requires special attention account for much of the problem (2). During June 2001--March 2003, one such outbreak in six eastern states accounted for >3,000 laboratory-confirmed infections (3). S. sonnei can also be transmitted through contaminated foods and through water used for drinking or recreational purposes (1). A new serotype of Shigella boydii has been reported in the United States and Canada (4).
Streptococcal Disease, Invasive, Group A
In 2003, approximately 1,190 invasive group A streptococcus (GAS) infections were reported by nine sites participating in the Active Bacterial Core Surveillance (ABCs) project of CDC's Emerging Infections Program (1). Passive reporting likely underestimates the number of invasive GAS infections in the United States. CDC estimates that approximately 11,000 cases of invasive GAS disease and 1,700 deaths occurred nationally during 2003. The incidence of invasive GAS infections in the United States has been relatively stable during the past 5 years (range: 3.1--3.8 per 100,000).
Streptococcus pneumoniae, Invasive Disease, Drug-Resistant
In 2003, the Active Bacterial Core Surveillance (ABCs) project of CDC's Emerging Infections Program (1) collected information on invasive pneumococcal disease, including drug-resistant Streptococcus pneumoniae, in nine states (California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New York, Oregon, and Tennessee). For the third straight year, the proportion of pneumococcal isolates that were drug resistant declined. Of the 3,075 S. pneumoniae isolates collected in 2003, 10.0% exhibited intermediate resistance to penicillin (minimum inhibitory concentration [MIC] 0.1--1.0 µg/mL), and 9.9% were fully resistant (MIC >2 µg/mL) (2). For cefotaxime, 2.3% of all isolates had intermediate resistance, and 0.8% were fully resistant in 2003. For erythromycin, 17.4% were resistant. Approximately one in eight (12.3%) isolates had reduced susceptibility to at least three classes of drugs commonly used to treat pneumococcal infections, a decline from a peak of one in five (18.3%) isolates in 2000.
In February 2000, the Food and Drug Administration licensed a pneumococcal conjugate vaccine for use in infants and young children. In October 2000, the Advisory Committee on Immunization Practices issued recommendations for vaccination of children aged <5 years (3). Vaccine use has reduced rates of invasive pneumococcal disease markedly among children, the vaccine's target age group, and among unvaccinated older persons and has also reduced racial disparities in disease risk (4).
During 2003, a total of 413 cases of congenital syphilis were reported (10.3 per 100,000 live births), compared with 412 in 2002. As with primary and secondary syphilis, the rate of congenital syphilis has declined sharply in recent years, from a peak of 107.3 per 100,000 in 1991 (1). The continuing decrease in the rate of congenital syphilis likely reflects the substantial reduction in the rate of primary and secondary syphilis among women. Congenital syphilis persists in the United States because a substantial number of women do not receive syphilis serologic testing until late in their pregnancies or not at all. This lack of screening is often related to absent or late prenatal care (2).
Syphilis, Primary and Secondary
During 2003, a total of 7,177 primary and secondary syphilis cases were reported, compared with 6,862 cases in 2002. During 1990--2000, the primary and secondary syphilis rate declined 90%, from 20.34 per 100,000 population to 2.12 per 100,000. The 2000 rate was the lowest since reporting began in 1941. The 2003 rate (2.5 per 100,000) marks the third consecutive year of increases in the overall rate. The 2003 rate was 19% higher than the reported rate in 2000 and reflects a 62% increase among men from 2000 and a 53% decrease among women (1). This disparity between men and women, observed across all racial and ethnic populations, along with reported outbreaks of syphilis in large urban areas among men who have sex with men (MSM), indicates that increases in syphilis are continuing to occur among MSM. Rates remain disproportionately high in the South and among non-Hispanic blacks, but these rates are continuing to decline (1,2).
In 2003, a total of 20 cases of tetanus were reported from 13 states and the District of Columbia. Four (20%) cases occurred among persons aged <25 years; none occurred among persons aged <18 years or neonates. Ten (50%) cases occurred among persons aged 25--59 years, and six (30%) cases occurred among persons aged >60 years. Although the annual number of reported cases continues to decrease, the percentage of cases among persons aged 25--59 years has increased during the last decade; previously, the majority of cases occurred among persons aged >60 years (1,2). Two (10%) cases were fatal.
During 2003, a total of 14,874 tuberculosis (TB) cases (rate: 5.1 cases per 100,000 population) were reported to CDC from the 50 states and the District of Columbia, representing a 1.3% decrease in cases and a 1.9% decrease in the rate from 2002. This decline is the smallest since 1992, when TB incidence peaked after a 7-year resurgence (1). In addition, the rate remains higher than the national interim objective of 3.5 cases per 100,000 population that was set for 2000 (2).
Disparities in TB rates persist among racial/ethnic minority populations. In descending order, the highest rates per 100,000 population were reported among Asians (29.3 [3,425 cases]), Native Hawaiian or Other Pacific Islanders (21.8 [85 cases]), non-Hispanic blacks (11.6 [4,145 cases]), Hispanics (10.6 [4,115 cases]), American Indian or Alaska Natives (6.1 [176 cases]), and non-Hispanic whites (1.4 [2,790 cases]). In 2003, for the first time, Hispanics (28%) equaled blacks (28%) as the racial/ethnic population with the largest percentage of cases prevalent (1).
In 2003, foreign-born persons accounted for 53% (7,902 cases) of the national case total, and 25 states reported at least 50% of their cases among foreign-born persons (1). The foreign-born prevalence represents an increase from 1993, when foreign-born persons accounted for 29% (7,354) of the national case total, and five states reported >50% of their cases among foreign-born persons (1). The TB rate among foreign-born persons has declined since 1993 (from 33.6 per 100,000 population in 1993 to 23.6 per 100,000 in 2003), but the decline among U.S.-born persons has been greater (from 7.4 in 1993 to 2.7 in 2003). In 2003, the case rate was 8.7 times greater among foreign-born persons than among U.S.-born persons; since 1993, this rate ratio has been increasing steadily.
CDC is collaborating with public health partners to implement TB control initiatives for recent international arrivals and residents along the border between the United States and Mexico and to strengthen TB programs in countries with a high incidence of TB disease (2). CDC has recently updated its comprehensive national action plan to reflect the realignment of its priorities with the 2000 Institute of Medicine report (3) and to ensure that priority prevention activities are undertaken with optimal collaboration and coordination among national and international public health partners (4).
A total of 129 cases of tularemia were reported in 2003, compared with an annual average of 120 cases for the preceding 3 years. Noteworthy were cases involving a child who apparently acquired tularemia from exposure to pet hamsters, an outbreak among commercially distributed prairie dogs, an unusual case of intra-abdominal tularemia in a patient with stomach cancer (1), and a cluster of pneumonic tularemia cases among lawn-care workers who mowed over a dead rabbit.
In 2003, a total of 356 cases of typhoid fever were reported in the United States. Despite recommendations that travelers to countries in which typhoid fever is endemic should be immunized with either of two effective vaccines available in the United States, approximately 74% of these cases occurred among persons who reported international travel during the preceding 6 weeks. Persons visiting friends and relatives in south Asia appear to be at particular risk, even during short visits (1). Salmonella Typhi strains with decreased susceptibility to ciprofloxacin are increasingly common in that region and should be treated with alternative antimicrobial agents (2). S. Typhi outbreaks in the United States are generally limited in size but can cause substantial morbidity; they are most often foodborne and warrant thorough investigation (3). A sexually transmitted outbreak of typhoid fever has been recognized and reported (4).
Varicella Cases and Deaths
In 2003, in all four states (Illinois, Michigan, Texas, and West Virginia) that have maintained consistent and adequate reporting levels¶ since 1990, the number of varicella cases was the lowest ever reported. Compared with 2002, cases declined 15.6%; compared with the prevaccine period 1993--1995, cases declined 81%. This decrease is associated with rapidly increasing vaccination coverage; during 2002--2003, vaccination coverage among children aged 19--35 months increased from 81% to 85%.
The Council of State and Territorial Epidemiologists (CSTE) recommends that all states establish statewide individual varicella case reporting by 2005 (1). The objectives of varicella surveillance at state and national levels are to 1) monitor the epidemiology of varicella by age and place and over time, 2) monitor the impact of widespread and increasing immunization on the epidemiology of varicella, and 3) allow prompt implementation of disease control measures.
In 1999, CSTE recommended that states report varicella deaths to CDC to monitor the impact of routine varicella vaccination on varicella-related mortality (2). In 2003, two states (Arkansas and Maryland) each reported one varicella death; ages of persons at time of death were 12 and 18 years. Reporting of varicella deaths is incomplete, which limits the usefulness of mortality data in assessing the impact of the varicella vaccination program. CDC encourages states to report varicella deaths, so the risk factors for varicella-related mortality can be identified, and the percentage of deaths that would have been directly preventable by following current recommendations for vaccination can be determined.
¶ Number of reported cases constituted >5% of the state's annual birth cohort.
West Nile Virus
During 2003, for the fifth consecutive year, epidemic and epizootic West Nile virus (WNV) activity occurred in the United States, including a substantial epidemic of neuroinvasive WNV disease in the Great Plains states, widespread perennial reemergence in areas of previous activity, and continued geographic expansion into western states.
In 2003, a total of 9,862 human WNV illness cases were reported by 45 states and the District of Columbia (DC). Six states (Colorado, Nebraska, North Dakota, South Dakota, Texas, and Wyoming) accounted for 77% of all reported human cases. Of 9,862 total cases, 2,866 (29%) were neuroinvasive, 6,830 (69%) were uncomplicated fever, and 166 (2%) were clinically unspecified. Of 2,866 neuroinvasive cases reported from 42 states and DC, 232 (8 %) were fatal. The 2003 WNV epidemic in the United States was comparable in size to, but focused further west than, the 2002 epidemic, which was centered in states along the Mississippi River Valley (1). Illness onset dates were April 14--December 5; the epidemic peak occurred during the week ending August 16. In 2003, a total of 818 presumptively WNV-viremic blood donors were identified through nationwide blood screening, and investigations were initiated to track birth outcomes among approximately 70 women with WNV illness acquired during pregnancy (2,3). Increased surveillance for human WNV illness cases might have resulted in improved surveillance for other domestic arboviruses of public health importance.
In 2003, WNV activity was reported from 2,358 counties in 46 states and D.C., including first-ever activity in Arizona, Nevada, and Utah, and first evidence of ecologic WNV transmission in California. In addition, 12,066 WNV-infected dead birds were reported from 43 states and D.C.; 5,145 WNV-infected horses and 106 other WNV-infected animals were reported from 43 states; and WNV seroconversions were reported in 1,956 sentinel bird flocks from 21 states. Culex mosquitoes accounted for 94% of 8,384 reported WNV-positive pools. Cx. tarsalis was the most commonly reported WNV-infected mosquito species and was considered a major epizootic and epidemic vector in western states.
In 2003, a total of 14 cases of neuroinvasive illness caused by eastern equine encephalitis virus were reported from eight states (Alabama, Florida, Georgia, Louisiana, New Jersey, North Carolina, South Carolina, and Virginia), equaling the maximum number reported to CDC in any year during 1964--2003. In addition, a large eastern equine encephalitis epizootic among equines (713 cases) and including dogs (two cases) and other veterinary species (18 cases) was reported in 19 states. During 1964--2003, a median of four (mean: five; range: 0--14) human cases were reported annually in the United States.
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