Impact of recurrent epidemics of hepatitis a virus infection on population immunity levels: Bristol Bay, Alaska.
The dynamics of population-based immunity were examined by using serologic surveys of 7 villages in rural Alaska between 2 epidemics of hepatitis A virus (HAV) and after the second epidemic (1988-1990). Among persons aged 2-30 years, the overall age-adjusted prevalence of antibody to HAV (anti-HAV) was 51% in 1983 and 49% in 1993 (P=.506). In children aged <5 years, prevalence rates were 0% and 11% in 1983 and 1993, respectively. The prevalence of HAV infection increased with age in both surveys. When examined by 5-year birth cohorts, anti-HAV prevalence increased in children born between 1979 and 1983 (P<.001). Between the 2 survey periods, 43 clinical cases of HAV infection were reported in these villages; all occurred from 1988 to 1990. Despite high overall prevalence of immunity, transmission during epidemics was facilitated by children aged <15 years susceptible to HAV. Little transmission occurred between epidemics. Vaccination of children against HAV should prevent future epidemics.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000413:Alaska / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology* / Q000276:immunology*; D035922:Hepatitis A Antibodies / Q000097:blood* / Q000276:immunology; D030041:Hepatitis A virus / Q000276:immunology; D006801:Humans; D015994:Incidence; D007223:Infant; D004930:Inuit; D008297:Male; D015995:Prevalence; D016036:Seroepidemiologic Studies; D013997:Time Factors
D035922:Hepatitis A Antibodies