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Rocky Mountain spotted fever (RMSF) is the most commonly reported fatal tick-borne disease in the United States. During 1997–2002, 3,649 cases of RMSF were reported to the Centers for Disease Control and Prevention via the National Electronic Telecommunications System for Surveillance; 2,589 case report forms, providing supplemental information, were also submitted. The average annual RMSF incidence during 1997–2002 was 2.2 cases/million persons. The annual incidence increased during 1997–2002 to a rate of 3.8 cases/million persons in 2002. The incidence was lowest among persons aged <5 and 10–29 years, and highest among adults aged 60–69 years. The overall case-fatality rate was 1.4%; the rate peaked in 1998 at 2.9% and declined to 0.7% in 2001 and 2002. Children <5 years of age had a case-fatality rate (5%) that was significantly greater than the rates for age groups <60 years of age, except for that for 40–49 years of age. Continued national surveillance is needed to assess the effectiveness of prevention efforts and early treatment in decreasing severe morbidity and mortality associated with RMSF.

This report describes the data accumulated during the first 5 years of national surveillance for the human ehrlichioses in the United States and territories, from its initiation in 1997 through 2001. Reported cases of human monocytic and granulocytic ehrlichiosis (HME and HGE) and cases of 'other ehrlichiosis' (OE), where the agent was unspecified, originated from 30 states. As anticipated, most HME cases were from the south-central and southeastern United States, while HGE was most commonly reported from the northeastern and upper-Midwestern region. State-level incident reports of 487 HME, 1,091 HGE, and 11 OE cases were evaluated. The average annual incidences of HME, HGE, and OE per million persons residing in states reporting disease were 0.7, 1.6, and 0.2, respectively. The median ages of HME (53 yr) and HGE cases (51 yr) were consistent with published patient series. Most (> 57) ehrlichiosis patients were male. The results suggest that national surveillance for the ehrlichioses, although imperfect in coverage, will help define endemic regions and may be useful for monitoring long-term trends. Although the data appear representative of the demographic profiles established for HME and HGE, rigorous evaluation of the system is required. Methods are proposed for evaluating the quality and representativeness of HME and HGE surveillance data, using well-established surveillance systems for Rocky Mountain spotted fever and Lyme disease.

The characteristics of rabies epizootics among raccoons were investigated in 11 eastern states along a North–South gradient from New York to North Carolina. Epizootics were defined as discrete intervals of time of at least 5 months in duration, when reported cases of raccoon rabies from an individual county exceeded the median value of raccoon rabies cases reported by that county over the entire period rabies was present among raccoons in the county. Over the ˜20-year study period, 35,000 cases of raccoon rabies were reported, and epizootics were detected from 251 (64.4%) of 390 counties. The median annual incidence was 0.14 epizootics per year. During the first defined epizootic in a county, the median total number of raccoons reported rabid was 47, with a median monthly incidence of rabies in raccoons of 3.1. The median lag time from the first report of a rabid raccoon in a county to the beginning of the first epizootic was 4 months. Significant differences in the annual incidence of epizootics and monthly incidence of rabid raccoons during epizootics were observed among different states. Although human population density and per capita health spending within counties were positively associated with increasing magnitude of epizootics, a significant difference in the characteristics of rabies epizootics in northern and southern states was apparent. We hypothesize that environmental conditions and perhaps human influence resulted in rabies epizootics in southern states that were smaller, less-frequent, and lacking in well-defined temporal structure compared with those in northern states.

Between 1981 and 1998, 37 cases of rabies were diagnosed in human beings in the United States. Information directly linking the cause of infection to animal bite was available for only eight of these cases. Indirect incrimination of the vector by analysis of cDNA sequences obtained by reverse transcriptase polymerase chain reaction of samples indicated that for all cases (1212) believed to have been acquired in foreign countries, variants of the rabies virus (VRVs) associated with dogs (712 involved known bite histories) were the cause of the rabies infections. In contrast, VRVs associated with bats (bat-associated VRVs or BAVs) were implicated as the cause of 88 (2225) of infections believed to have been acquired within the United States (122 involved known bite histories). Sequence analyses revealed that a single BAV (LnPs), associated with rabid silver-haired (Lasionycteris noctivagans) and Eastern pipistrelle (Pipistrellus subflavus) bats, was implicated in 73 (1622) of bat-associated infections. Silver-haired bats are predominantly solitary and migratory. Eastern pipistrelle bats may occur individually or in small clusters. Both species are only infrequently submitted for rabies testing. Unrecognized bites and unique properties of the LnPs BAV may explain its association with the majority of rabies infections in human beings in the United States.

In an in vitro model, 20 condoms containing 0.9 mL of 6.6% (vol/vol) nonoxynol 9 and ten condoms without nonoxynol 9 were tested as physical and chemical barriers against human immunodeficiency virus (HIV). Each condom was mounted on a hollow dildo and placed in a glass cylinder. The HIV inoculum and HIV-free medium were placed on opposite sites of the condom. Intercourse was simulated by pumping the dildo up and down in the cylinder before and after deliberate rupture of the condom. Samples for HIV culture were taken from outside and inside the condom, before and after rupture. After rupture of nonoxynol 9—containing condoms, an outside nonoxynol 9 concentration of 0.25% was reached. No condom without nonoxynol 9 leaked HIV before rupture, but after rupture HIV could be detected in medium outside of seven of ten condoms tested. In none of 20 nonoxynol 9—containing condoms could HIV be detected in outside medium after rupture. Thus, undamaged condoms provide an effective physical barrier against HIV, and nonoxynol 9 may provide an effective chemical barrier as well.(JAMA 1988;259:1851-1853)

In studies of Lassa fever in Sierra Leone, the prevalence. of human antibody to Lassa virus ranged from 8% to 52%. Mastomys natalensis, the reservoir of Lassa virus, constituted 50%–60% of the rodents captured in houses but only 10%–20% of those captured in surrounding agriculture and bush areas (χ2 = 90.2, P < 10−6 , dƒ = 1), a finding suggesting that houses are the most-important location for transmission of Lassa virus. Viral infection of Mastomys from houses ranged from 0% to 80%. The incidence of seroconversions in susceptible persons ranged from 5% to 22% per year; the ratio of illness to infection ranged from 9% to 26%, and the proportion of febrile illness associated with seroconversion was 5%–14%. Eightfold rises in titer of antibody occurred in 1%–18% of the antibody-positive population, a result suggesting reinfection. We estimate the ratio of fatalities to infection to be 1%–2%, a rate lower than estimates based on hospitalized cases. The high incidence of Lassa fever makes it a major problem in West Africa.

Rabies is caused by a single-stranded, negative-sense RNA virus, maintained in nature by a variety of animal reservoirs. Rabies virus infects the central nervous system, resulting in progressive encephalopathy and ultimately death in an infected human. Globally, the risk of contracting rabies for humans is greatest in regions of the developing world where dog rabies is enzootic. Where rabies in dogs has been eliminated or otherwise controlled through vaccination programs, the disease can be maintained by wildlife. Wildlife primarily involved in maintenance of transmission cycles are carnivores and bats. Persons having frequent contact with wildlife, such as mammalogists, are at greater risk than the general population for exposure to rabid animals. Rabies prevention can be achieved by elimination of exposure and by vaccination through preexposure prophylaxis and postexposure treatment. Preexposure rabies prophylaxis affords a measure of protection for unrecognized rabies exposures and simplifies postexposure treatment. Postexposure treatment is recommended following exposure to a potentially rabid animal and involves treatment of wound and administration of rabies vaccine as well as rabies immune globulin for individuals not previously vaccinated. Future research on rabies is necessary to define the effects of infection on wildlife populations and to evaluate the potential for intervening in wildlife transmission using oral rabies vaccines.

In May 1993, an outbreak of hantavirus pulmonary syndrome (HPS) occurred in the southwestern United States. A case-control study determined risk factors for HPS. Seventeen case-patients were compared with 3 groups of controls: members of case-patient households (household controls), members of neighboring households (near controls), and members of randomly selected households 24 km away (far controls). Investigators trapped more small rodents at case households than at near (P = .03) or far control households (P = .02). After the number of small rodents was controlled for, case-patients were more likely than household controls to hand plow (odds ratio [OR], 12.3; 95% confidence interval [CI], 1.1-143.0) or to clean feed storage areas (OR, 33.4; 95% CI, 1.7-666.0). Case-patients were more likely than near controls to plant (OR, 6.2; 95% CI, 1.1-34.0) and more likely than far controls to clean animal sheds (OR, 11.9; 95% CI, 1.4-103.0). Peridomestic cleaning, agricultural activities, and an increased number of small rodents at the household were associated with HPS.

An outbreak of hantavirus pulmonary syndrome (HPS) in the southwestern United States was etiologically linked to a newly recognized hantavirus. Knowledge that hantaviruses are maintained in rodent reservoirs stimulated a field and laboratory investigation of 1696 small mammals of 31 species. The most commonly captured rodent, the deer mouse (Peromyscus maniculatus), had the highest antibody prevalence (30%) to four hantavirus antigens. Antibody also was detected in 10 other species of rodent and in 1 species of rabbit. Reverse transcriptase-polymerase chain reaction (RT-PCR) products of hantavirus from rodent tissues were indistinguishable from those from human HPS patients. More than 96% of the seropositive P. maniculatus were positive by RT-PCR, suggesting chronic infection. Antibody prevalences were similar among P. maniculatus trapped from Arizona (33%), New Mexico (29%), and Colorado (29%). The numeric dominance of P. maniculatus, the high prevalence of antibody, and the RT-PCR findings implicate this species as the primary rodent reservoir for a new hantavirus in the southwestern United States.