PREVALENCE OF ENTERIC HEPATITIS A AND E VIRUSES IN THE MEKONG RIVER

Abstract. A study of antibody prevalence for hepatitis A virus (HAV) and hepatitis E virus (HEV) was carried out in southwestern Vietnam in an area adjacent to a known focus of epidemic HEV transmission. The purpose of this investigation was first to provide a prevalence measure of hepatitis infections, and second to determine the outbreak potential of HEV as a function of the susceptible population. Blood specimens collected from 646 persons in randomly selected village hamlets were examined by an ELISA for anti-HEV IgG and anti-HAV IgG. The prev-alences of anti-HEV IgG and anti-HAV IgG were 9 % and 97%, respectively. There was a significant increase (P, 0.01) in age-specific anti-HEV IgG. A notable increase in anti-HAV IgG prevalence (P, 0.0001) occurred between child populations 0–4 (64%) and 5–9 (95%) years of age. No evidence of familial clustering of anti-HEV IgG-positive individuals was detected, and household crowding was not associated with the spread of HEV. Boiling of water was found to be of protective value against HEV transmission. A relatively low prevalence of anti-HEV indicates consid-erable HEV outbreak potential, against a background of 1) poor, water-related hygiene/sanitation, 2) dependence on a (likely human/animal waste)–contaminated Mekong riverine system, and 3) periodic river flooding. Epidemic and sporadic hepatitis E virus (HEV) trans-mission has been documented throughout the developing world1 (Balayan MS, unpublished data). In southeast Asi