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The 1996 national total of 39 laboratory-confirmed California serogroup viral encephalitis cases (all of which were La Crosse encephalitis cases) represents a 95% increase over the 1995 total. This is the largest annual total of such cases reported since 1982. Reports from West Virginia and Ohio account for nearly 100% of the increase. Much of the increase in West Virginia may be attributable to the recent implementation of an active surveillance system for this disease. La Crosse encephalitis is endemic in the eastern United States; where it is associated with exposure to deciduous forests and Aedes triseriatus (the eastern treehole mosquito).
From 1990 through 1995, the number of reported cases of coccidioidomycosis in Arizona increased by 144%. To characterize the trends and impact of coccidioidomycosis in Arizona, the Arizona Department of Health Services analyzed surveillance, death-certificate, and hospital-discharge data. These data indicated that, during 1990-1995, coccidioidomycosis in Arizona disproportionately affected persons aged greater than or equal to 65 years and persons with HIV infection.
National reporting for cryptosporidiosis began in 1995 with 2,972 cases reported from 27 states. In 1996, a total of 2,426 cases were reported from 42 states. Because the diagnosis of Cryptosporidium often is not considered, and because laboratories do not routinely test for Cryptosporidium infection, cryptosporidiosis continues to be underdiagnosed and underreported.
Hantavirus pulmonary syndrome (HPS) is a pan-American viral zoonosis caused by Sin Nombre virus and other New World hantaviruses which, in the United States, include Bayou virus, Black Creek Canal virus, and New York-1 virus. The identified rodent reservoirs for Sin Nombre, New York-1, Black Creek Canal, and Bayou viruses are Peromyscus maniculatus (deer mouse), Peromyscus leucopus (white-footed mouse), Sigmodon hispidus (cotton rat), and Oryzomys palustris (rice rat), respectively. Cases of HPS have been identified in the continental United States, Canada, Argentina, Brazil, Chile, Paraguay, and Uruguay. As of May 1, 1997, national surveillance for HPS has identified 160 confirmed cases in 26 states (case-fatality: 47.5%); 22 of these cases were diagnosed in 1996.
In the United States, virtually all cases of post-diarrheal hemolytic uremic syndrome (HUS) are caused by infection with Escherichia coli O157:H7 or other Shiga toxin-producing organisms. During 1996, the first year of national reporting, 18 states reported 102 cases of post-diarrheal HUS. Median age of patients was 5 years (range: 1-79), and 75% of cases occurred from June through October.
In 1996, the Advisory Committee on Immunization Practices (ACIP) issued recommendations for the prevention of hepatitis A through active or passive immunization (MMWR 1996;45[No. RR-15]). The report provides recommendations for use of the recently licensed hepatitis A vaccines (i.e.,HAVRIX®, manufactured by SmithKline Beecham Biologicals, and VAQTA®, manufactured by Merck & Company, Inc.). For communities with high rates of hepatitis A and periodic outbreaks (peak rates: 700 reported cases per 100,000 population), routine vaccination of children aged 2 years and catchup vaccination of older children is recommended. To control outbreaks in communities with intermediate rates of hepatitis A (i.e., 50-200 reported cases per 100,000 population), vaccination programs targeting subpopulations with the highest rates of disease may be considered. In these communities, ongoing routine vaccination of young children should be implemented to prevent future outbreaks.
In 1996, a total of 29 states conducted surveillance of human immunodeficiency virus (HIV) infection in children. These states reported 249 HIV-infected children who had not progressed to acquired immunodeficiency syndrome (AIDS) and 184 children who had AIDS. During 1996, these states received 1,720 additional reports of children who were born to HIV-infected mothers but who require follow up with providers to determine their HIV infection status.
In 1996, a total of 16,455 cases of Lyme disease were reported to CDC by 45 states and the District of Columbia (overall incidence: 6.2 per 100,000 population), representing a 41% increase from the 11,700 cases reported in 1995 and a 26% increase from the 13,043 cases reported in 1994. As in previous years, most cases were reported from the mid-Atlantic, northeast, and north-central regions. Eight states reported Lyme disease incidences that were higher than the overall national rate (Connecticut, 94.8; Rhode Island, 53.9; New York, 29.2; New Jersey, 27.4; Delaware, 23.9; Pennsylvania, 23.3; Maryland, 8.8; and Wisconsin, 7.7); these states accounted for 14,959 (91%) of the nationally reported cases. In 1996, zero cases were reported from five states (i.e., Alaska, Arizona, Colorado, Montana, and South Dakota). The increase in reported Lyme disease cases in 1996 probably represents a combination of increased tick density in the northeastern United States, enhanced health-care provider awareness and reporting, and improved laboratory surveillance. In addition, case reporting has been enhanced through the availability of CDC resources for Lyme disease surveillance in eight states (i.e., Connecticut, Michigan, Minnesota, New Jersey, New York, Oregon, Rhode Island, and West Virginia).
One of the persons who died was infected through bites by infective prairie dog fleas; the other was infected by exposure to a pet cat with plague. These cases underscore the need for health-care providers in areas with endemic plague to maintain a high level of awareness about the risk for plague in their patients. Revised recommendations for the use of plague vaccine have been approved by the Advisory Committee on Immunization Practices (ACIP) and published in MMWR (1996;45[No. RR-14]). During 1970-1995, 341 cases of human plague (average 13 cases per year) were reported in the U.S. Of these cases, 80% occurred in the southwestern states of New Mexico, Arizona, and Colorado, 9% were reported from California, and nine other western states reported smaller numbers of cases. Most likely modes of transmission were determined for 286 of these cases and included flea bite (n=223; 78%); direct contact with infected animals (n=56; 20%); and inhalation of respiratory droplets from infected animals (n=7; 2%). Five of the seven persons infected by inhalation were known to be exposed in infected domestic cats. The overall mortality was 15%.
In July 1996, a 45-year-old resident of Tennessee planning a trip to Brazil elected not to drive to a nearby city for a recommended immunization with yellow fever (YF) vaccine at a World Health Organization designated Yellow Fever Vaccine Administration Center. After a 9-day fishing trip on the Amazon and Rio Negro rivers, he returned to Tennessee where he soon developed symptoms of fever, chills, headache, joint pains, and myalgias. His condition deteriorated further with development of a coagulopathy, bleeding from multiple sites, and shock. He died on the 6th day of hospitalization. YF virus was isolated from premortem serum specimens and was identified both by polymerase chain reaction and conventional virologic methods. This case was the first recognized and documented importation of YF into the United States since 1924.
In 1996, the largest reported outbreak of cyclosporiasis occurred in North America. A total of 1,465 cases were reported by 20 states and the District of Columbia in the United States and by two provinces in Canada. Consumption of Guatemalan raspberries was associated with illness.
Forty-four laboratory-confirmed cases of dengue were imported into the United States in 1996 and diagnosed at the CDC Dengue Branch. This number is a decrease from the unusually substantial number of cases reported in 1995 (i.e., 86 cases), which was associated with the occurrence of major outbreaks of dengue and dengue hemorrhagic fever (DHF) in most tropical countries of the Americas. However, the total number of dengue and DHF cases reported by Pan American Health Organization member countries in 1996 (n=250,707) was only slightly lower than the total for 1995 (n=284,483). Most countries in the region, especially Central America and the Caribbean islands, reported a substantially lower incidence of dengue in 1996, but major increases were noted in Brazil (with 175,751 cases reported), Mexico (20,687 cases), and Trinidad and Tobago (3,983 cases).
In the early 1990s, the percentage of nosocomial enterococci reported from intensive care units (ICUs) as being resistant to vancomycin substantially increased, from 7.1% in 1992 to 11.6% in 1993 and 13.8% in 1994; the increase leveled off in 1995 (12.8%) but has continued its increase in 1996 (16.7%). Data from the hospital-based National Nosocomial Infections Surveillance System also indicate that for isolates from outside ICUs, the percentage of resistant enterococci has continued to rise (i.e.,from 2.8% in 1992 to 4.8% in 1993 and to 12.2% in 1996). This represents a shift in the hospital location of patients with vancomycin resistant enterococcus (VRE).
During the summer of 1996, a substantial epidemic (i.e., approximately 500 clinical cases, nearly 300 of them serologically confirmed) of West Nile fever occurred in Bucharest and southeastern Romania. Most recognized cases manifested as meningitis, encephalitis, or meningoencephalitis. Approximately 5% of confirmed cases were fatal, with the highest case-fatality ratios in the elderly. The abundant mosquito subspecies Culex pipiens pipiens, which prefers organically polluted water sources for reproduction, was implicated as the urban vector. West Nile virus is a mosquitoborne neurotropic flavivirus that occurs in parts of Africa, Asia, and Europe and is closely related antigenically to St. Louis encephalitis virus, which occurs in North America.
During the second half of 1996, an epidemic of o'nyong-nyong fever was documented in rural south-central Uganda. This represents only the second recognized epidemic of this disease since its initial description in 1962. O'nyong-nyong virus is a mosquito-borne alphavirus that causes a febrile disease characterized by generalized, debilitating joint pains, and often the disease is accompanied by a maculopapular skin rash and lymphadenopathy. Fatalities are rare, but morbidity often is significant. The typical epidemic mosquito vectors are Anopheles funestus and An. gambiae, two of the region's major malaria vectors.
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