Routes of transmission in the hepatitis E epidemic of Saharanpur

Abstract

A large waterborne epidemic of hepatitis E occurred in the city of Saharanpur (Uttar Pradesh, India) between December 1992 and April 1993. A random survey was conducted in the affected area of Saharanpur. Source of water supply, number of family members, number and characteristics of affected persons were noted. Blood, stool and water samples were collected. The incidence of hepatitis was 14% in the affected area of the city. A total of 3682 individuals were affected with the disease. Attack rate for adults was significantly higher than the children aged < 15 years (17% vs 7%; p < 0.0001). Among the adults, the attack rate was higher for males than females (23% vs 12%; p < 0.0001). The incidence of hepatitis was greater in persons using the municipal water supply (17%) as compared to hand pump (0.9%) or tubewell water (0%). There was a single peak in the epidemic. Of the 56 fresh cases, 38 (64%) occurred within two weeks, 14 within 2-4 weeks and 4 within 4-6 weeks of index cases. Serologic markers for acute hepatitis A, B and C were absent. IgM anti-HEV was positive in 20 out of 24 sera tested. Immune electron microscopy detected 27-34 nm virus-like particles (VLPs) in 2 of 8 stool specimens and in 1 of 3 water samples. The epidemic occurred due to leakage of municipal water supply pipes passing through the sewerage holes. A large waterborne epidemic of hepatitis E resulted due to contaminated water supply. VLPs were detected in water. Adults and males were commonly affected. There was no person-to-person spread.