Investigation of a hepatitis A outbreak from Shimla Himachal Pradesh.

Background & objective: Hepatitis A is an enterically transmitted viral disease, highly prevalent in India and mainly presents as a paediatric sporadic disease. This study investigated an outbreak of viral hepatitis at Shimla, Himachal Pradesh, India, during January-March 2007. Methods: Eighty seven blood samples, 3 water samples and 2 sewage samples were collected. Serum samples were tested for IgM and IgG anti HAV and IgM and IgG anti HEV antibodies. Serum, sewage and water samples were tested for HAV-RNA by nested RT- PCR. Nearly complete full genome (excluding extreme 5’ end) was amplified from one serum sample. Results: The hepatitis cases were mainly seen among children and young adults and 63.2 per cent (55/88) were positive for anti-HAV IgM. These cases were reported from the areas getting water supply from Ashwani Khud water supply system. This water purification system received water from a natural stream in which treated sewage water was let into 4 km upstream the collection point since one year. HAV-RNA present in serum, sewage and water samples showed 100 per cent sequence homology. Phylogenetic analysis based on 5’ non coding (5’ NC) and nearly complete genome showed the evidence of HAV genotype IIIA in all the samples. Interpretation and conclusion: The aetiological agent of the present outbreak was hepatitis A virus which is emerging in an outbreak form in India, emphasizing a definite need for formulating vaccination / control strategies.

Co-circulation of genotypes IA and IB of hepatitis A virus in Northeast Brazil

The Northeast region is the location of most cases of acute hepatitis A virus (HAV) in Brazil. In the present study, the genotypes of HAV strains from Pernambuco State, one of most populous states in the Northeast region, were characterized. Blood samples positive for anti-HAV IgM from 145 individuals (mean age = 29.1 years), collected during 2002 and 2003, were submitted to nested RT-PCR for amplification of the 5'non-translated region (5'NTR) and VP1/2A regions of the HAV genome. The VP1/2A and 5'NTR regions were amplified in 39 and 21 percent of the samples, respectively. Nucleotide sequencing was carried out in 46 percent of VP1/2A and in 53 percent of 5'NTR isolates. The identity in nucleotide sequence of the VP1/2A region ranged from 93.6 to 100.0 percent. Phylogenetic analysis of the VP1/2A sequences showed that 65 percent belong to sub-genotype IA and 35 percent to sub-genotype IB. Co-circulation of both sub-genotypes was observed in the two years studied. Distinct clusters of highly related sequences were observed in both sub-genotypes, suggesting endemic circulation of HAV strains in this area. In the 5'NTR isolates, 92.7-99.2 percent identity was observed and two isolates presented one deletion at position 413. Phylogenetic analysis showed that genotype IA strains cluster in the tree in the same way as genotype IB strains, but one IIIA isolate from Spain clusters with genotype IB strains. These results do not allow us to state that 5'NTR could be used to genotype HAV sequences. This is the first report of co-circulation of sub-genotypes IA and IB in this region, providing additional information about the molecular epidemiology of HAV strains in Brazil.