Analysis of an Outbreak of Human Rabies in 2009 in Hanzhong District, Shaanxi Province, China

Abstract

Between March and August 2009, there was an outbreak of rabies in both humans and dogs in Hanzhong District, Shaanxi province, China. About 7300 humans were bitten by dogs and 20 died of rabies due to failure to perform postexposure prophylaxis. The local authorities therefore conducted a dog slaughter campaign. From a random selection of brains of dogs culled in the campaign, 0/27 tested positive for rabies virus by immunofluorescence. Of two dogs known to have bitten humans, one was shown to contain live rabies virus by immunofluorescence and mouse intracerebral inoculation. Serological studies during the outbreak revealed that only 1/27 dog was antibody positive: after a mass vaccination campaign, 20.8% seroconverted. Lack of canine vaccination was clearly the main reason for dog rabies spread and human infection. Phylogenetic analysis of a virus isolate showed that its genomic sequence was closely related to the clade 1 rabies strains widely circulating in China. The highest homology was found with the isolate circulating in Sichuan province, a neighboring province south of Shaanxi, indicating the spread of rabies from the south to the north.