Molecular characterization of hepatitis A virus from a large outbreak from Kerala, India.

ABSTRACT

BACKGROUND & OBJECTIVES: Hepatitis A is highly prevalent in India and mainly presents as a sporadic disease. This study investigated an outbreak of viral hepatitis at Medical College Hospital area, Kottayam, Kerala state, India during January 2005. METHODS: Blood (133), faecal (1), sewage (4), and water samples (13) were collected. Sera were tested for IgG- and IgM-anti-HAV and IgM antibodies against hepatitis E (IgM-anti-HEV). Sewage, faeces and water samples were tested for HAV RNA in nested RT-PCR and HAV RNA positive samples were further processed for RNA quantitation using Real Time PCR. RESULTS: Of the 1180 total cases, 540 were reported from Medical college area. Two deaths were reported among doctors. Patients from the community gave a previous history of visit to medical college hospital area. The sewage treatment plant at the campus was non-functional since 1990 and the untreated sewage was constantly overflowing and getting mixed with a canal. At the time of the study, all the water sources were superchlorinated. HAV RNA was present in the faeces of hepatitis A patient (1.36 x 10(7) copies/ml), sewage tank (2.57 x 10(3) copies/ml and the canal (<100 copies/ml). None of the 13 water samples concentrated 10,000-fold and the soil sample showed presence of HAV RNA. Phylogenetic analysis based on 5'-non-coding and P2 regions showed HAV-genotype IIIA in all samples. INTERPRETATION & CONCLUSION: The aetiological agent of the present outbreak was found to be HAV. Epidemic hepatitis A (genotype-IIIA) is emerging in Indian adults, emphasizing the need for definite policy for control.