Presence of hepatitis E virus in sewage in northern India: frequency and seasonal pattern

Outbreaks of acute hepatitis E, associated with consumption of contaminated drinking water, are frequent in India. Sewage is a major source for contamination of surface water. Data on the presence of hepatitis E virus (HEV) in sewage in India are limited. The aim of this study was to look for the presence of HEV RNA in concentrates of sewage specimens collected from a major open sewage drain in Lucknow, India during August 2004 to July 2006, by the polymerase chain reaction, using primers specific for human HEV (genotype 1) or Indian swine HEV (genotype 4). Of the 192 sewage specimens tested, 79 (41%) showed presence of human HEV RNA. The positivity rate was higher during the second year (52/103 [51%]) than during the first year (27/89 [30%]; P = 0.005). The seasonal pattern of HEV RNA positivity was as follows: winter months (November to February): 28 of 61 (46%); summer months (March to June): 36 of 66 (55%); and, monsoon months (July to October) 15 of 65 (23%). There was no reported outbreak of hepatitis E in the city during the study period. Swine HEV RNA was not detected in any of the 69 specimens tested. Repeat testing confirmed the reproducibility of the results. In addition, nucleic acid sequencing of six sewage isolates showed that these belonged to HEV genotype 1. The study suggests that HEV infection and fecal viral excretion may be common in HEV-endemic regions throughout the year even during non-epidemic periods