Hepatitis B virus infection in northern India. Prevalence, subtypes, and seasonal variation.

Previous reports from India have been limited to the incidences of hepatitis B antigen (HB Ag) in health and disease. This paper reports on a study undertaken over the last two years to determine the incidence of hepatitis B virus infection, the serotypes prevalent among apparently healthy individuals and patients with liver diseases, and the seasonal incidence of sporadic acute hepatitis in this geographic area. The incidences of infection in health and disease show an endemic pattern. The Y subtype predominates among healthy carriers and patients with chronic liver diseases, whereas the D subtype predominates in patients with acute hepatitis. The similarity of subtypes of HB Ag among the majority of healthy carriers and patients with chronic liver diseases suggests that the majority of asymptomatic carriers (subclinically infected) would develop chronic liver disease. The proportion of HB Ag-positive cases of acute hepatitis was significantly higher during the two summer seasons than during the two winter seasons; this could be due to more frequent transmission of the virus by the faecal/urinary-oral route and its activation during the summer months, especially in areas with poor hygienic conditions. The urinary/faecal excretion of virus could thus maintain the natural transmission of the virus in such an environment.