Seroepidemiology of hepatitis A infection in India: changing pattern

Recent changes in the epidemiology of hepatitis A virus (HAV) infection and the availability of effective vaccines have renewed interest in this infection. We determined the age-related prevalence of anti-HAV antibodies in India and looked for differences by known risk factors for HAV infection.

In this prospective study, serum samples obtained from 1612 subjects aged 1 to 60 at six centers in five cities (Calcutta, Cochin, Indore, Jaipur and Patna) during the period February to August 1998 were tested for anti-HAV antibodies. Demographic and socio-economic information was obtained by questionnaire.

The overall seroprevalence rate was 65.9%, varying from 26.2% to 85.3% in various cities; there was no difference between males and females. Seropositivity increased with age from 52.2% in the 1-5 year age group to 80.8% in those aged 16 years or more. Seroprevalence rates were significantly lower in those aged 1-5 years compared with other age groups (p<0.0001). There was no difference in seroprevalence between those with monthly family income Rs 5001. Multivariate analysis showed that anti-HAV seroprevalence varied significantly by source of water supply, being highest when the supply was municipal.

Our results indicate an epidemiological pattern of intermediate endemicity. This finding has public health implications as it indicates that a significant proportion of the Indian adolescent and adult population is at risk of HAV infection.