An outbreak of viral hepatitis in a housing complex of north Calcutta.

In a housing complex of North Calcutta, a sudden outbreak of hepatitis occurred between September 1988 and January 1989. Of 620 residents, 8.5 per cent were affected. Majority of the cases occurred among the adult population and the case fatality rate was 3.8 per cent. The epidemic was common source with peak incidence in the month of November. The source of infection was most likely drinking water supplied by the Municipal Corporation which was found to be contaminated by faecal coli. Epidemic was suspected to be caused by enterically transmitted Non A Non B hepatitis virus as the serological testing of all 18 blood samples were negative for anti-HAVIgM titre and only one sample was positive for HBsAg.