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La Crosse virus infection and disease in western North Carolina
Insights
La Crosse virus persists in western North Carolina, evidenced by 15 years of cases and mosquito infections. Enhanced surveillance is crucial to understand its prevalence in the southeastern United States.
Area of Science:
- Epidemiology
- Arbovirology
- Public Health
Background:
- La Crosse virus causes encephalitis, particularly in children.
- Previous La Crosse virus activity was noted in the Cherokee area in 1964-1965.
- Limited reporting from the southeastern US may be due to insufficient surveillance.
Purpose of the Study:
- To document active La Crosse virus infections in western North Carolina.
- To investigate the persistence of La Crosse virus in the Cherokee reservation area.
- To assess the potential public health significance of La Crosse virus in the Southeast.
Main Methods:
- Active surveillance for La Crosse infection from 1977-1979.
- Isolation of La Crosse virus from Aedes triseriatus mosquitoes.
- Serological testing for La Crosse virus antibodies in children.
Main Results:
- Twelve laboratory-confirmed cases of La Crosse infection in children were identified.
- La Crosse virus was detected in local Aedes triseriatus mosquito populations.
- Antibody prevalence increased in children over time, indicating sustained viral activity for at least 15 years.
Conclusions:
- La Crosse virus has been endemic in the Cherokee area for over 15 years.
- The findings suggest that La Crosse virus may be underestimated in the southeastern US.
- Increased surveillance efforts are recommended to determine the true burden of La Crosse virus disease.
Abstract:
Active surveillance for La Crosse infection from 1977 to 1979 revealed 12 laboratory documented cases in children from the Cherokee reservation and nearby areas of western North Carolina. The annual rate of hospitalization with La Crosse virus was isolated from two of 34 pools of male and one of 34 pools of female Aedes triseriatus mosquitoes reared from larvae collected around the residences of reservation children who had been hospitalized with encephalitis. The occurrence of the recent cases, the history of cases in 1964 and 1965, and the demonstration of antibodies to La Crosse virus in sera from second grade children collected in 1968 (2%), in 1978 (4.5%), and in high school students in 1979 (11.3%), indicate that La Crosse has persisted in the Cherokee area for at least 15 years. La Crosse infection is infrequently reported from the southeast, but this may reflect inactive surveillance. More frequent testing would reveal whether La Crosse is a significant health problem in other areas of the southeast.