Identification of a new strain of hepatitis E virus from an outbreak in Namibia in 1995

Endemic circulation of hepatitis E virus (HEV) in Namibia was suspected from serological data during an outbreak of non-A, non-B hepatitis in Rundu in 1995. The source of the outbreak was suspected to be the water supply, which had been compromised approximately 6 months earlier. Four HEV isolates from four different persons in this outbreak were successfully amplified, sequenced and analysed over a 451 bp region of a subgenomic fragment from the 3' end of the genome in ORF2. Phylogenetic analysis showed that the four Namibian HEV isolates clustered with a Mexican isolate in genotype II and shared 85.8-86.3 % nucleotide identity with the 1987 Mexican isolate, but were only 77.6-79.6 % similar to other African isolates. HEV isolated from the same region of Namibia in 1983 was reported to cluster in genotype I. However, virus isolates from sporadic cases of HEV isolated in 1997/8 in Nigeria were also from genotype II.