The age-specific seroprevalence of antibody to hepatitis A virus (HAV) and antibody to hepatitis E virus (HEV) were studied in persons in Pune, India, where both viruses are endemic. The data showed that HAV infected the majority of persons by age 3 years and virtually 100% by late childhood. In contrast, infection with HEV was rare in children and did not reach peak prevalence (33%-40%) until early adulthood. The reason for the differences in infection rates between HAV and HEV is not known. Age-specific antibody patterns in serum samples obtained 10 years apart show that neither HAV nor HEV has diminished in medical importance in this Indian community.

Many epidemics of water-borne hepatitis have occurred throughout India. These were thought to be epidemics of hepatitis A until 1980, when evidence for an enterically transmitted non-A, non-B hepatitis was first reported. Subsequently, hepatitis E virus was discovered and most recent dem of enterically ted non-A, non-B hepatitis have been attributed to hepatitis E virus infection. However, only a limited number of cases have been confirmed by immuno electron microscopy, polymerase chain reaction, or seroconversion. In the present study we have performed a retrospective seroepidemiologic study of 17 epidemics of waterborne hepatitis in India. We have confirmed that 16 of the 17 epidemics were caused at least in part by serologically closely related hepatitis E viruses. However, one epidemic, in the Andaman Islands, and possibly a signifnt minrit of cases in other epidemics, appears to have been caused by a previously unrecognized hepatitis agent.

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Non-A, non-B (NANB) hepatitis viruses are now classified as hepatitis E (enterically transmitted) and hepatitis C (parenterally transmitted). India experiences a large number of epidemics of the enteric disease every year. In addition, about 70% of the sporadic cases among adults are also due to NANB hepatitis. With the availability of an immunoblot assay for the detection of anti-HEV-IgM and the polymerase chain reaction (PCR) for the detection of HCV-RNA, serum samples from epidemic and sporadic NANB patients were screened for these markers. We found that a large number of cases from the epidemics were HEV, though a few remained undiagnosed, while of the sporadic cases only a few could be diagnosed as HCV or HEV; a large proportion remained undiagnosed.

Very accurate eigenvalues of the two-well oscillator (H(k, k) = pkx + Ax ) are obtained by a nonperturbative method. The splitting between the pairs of lower eigenvalues is found to be remarkably well estimated by the WKB approximation. It is observed that the scaling properties of the exact eigenvalues with 'respect to the parameters in the Hamiltonian are retained in the WXB approximation.