EPIDEMIC AND SPORADIC HEPATITIS-E VIRUS TRANSMISSION IN WEST KALIMANTAN (BORNEO), INDONESIA

A cross-sectional survey was conducted in West Kalimantan (Borneo), In donesia to geographically profile hepatitis E virus (HEV) prevalence i n the riverine areas recognized as the foci of epidemic HEV transmissi on in 1987. Additionally, a contiguous, although distinct, population with no identifiable historical exposure to epidemic HEV was surveyed downstream for comparative purposes. Eight hundred eighty-five sera we re assayed by enzyme immunoabsorbent assay for anti-HEV IgG and anti-h epatitis A virus (HAV) IgG markers. A very high percent (90%) of both the outbreak and comparison populations was anti-HAV IgG positive by t he age of nine years. In contrast, the prevalence of anti-HEV IgG in t he outbreak area (50%) was significantly higher than in the comparison area (23%) (P < 0.0001). In both the outbreak and comparison areas, a nti-HEV IgG prevalence increased with age (< 0.0001), except for the g roup greater than or equal to 50 years of age. The prevalence (53%) of antibody to HEV in the population greater than or equal to seven year s of age from the outbreak area (alive during the actual 1987 outbreak ) was significantly (P < 0.0001) greater than among the children < sev en years of age (born after the outbreak) (15%). However, anti-HEV IgG prevalence among the population from the comparison area did not diff er significantly between the greater than or equal to seven- (23%) and < seven- (20%) year-old age groups. The percentage of anti-HEV IgG-po sitive individuals among males (47%) from the outbreak area was lower (P < 0.05) compared with females (55%). While overall usage of river w ater for drinking purposes was not universal, dependence on river wate r as a primary source was significantly higher (P < 0.001) in househol ds from the outbreak area (60%) compared with the comparison area (30% ). This study indicates persistence of an anti-HEV IgG response in a l arge percentage of the population seven years after an epidemic of HEV infections. Also, the relatively high prevalence (15%) of anti-HEV in children , seven years of age from the outbreak area reflects continu ing, sporadic infections.