Japan Reports HPAI in Wild Birds at Zoo
JAPAN - Wild birds at a zoo on Honshu have been found with H5 highly pathogenic avian influenza (HPAI).The veterinary authority sent an Immediate Notification dated 20 December to the World Organisation for Animal Health (OIE).
The report describes an outbreak of HPAI at Takaoka kojo(Old Castle) Park Zoo in Takaoka city in Toyama prefecture on Honshu. The outbreak started on 16 December and involved 14 captive wild birds, including 10 mute swans (four of which died), two ducks and two black swans. The affected birds have been destroyed.
According to the report, it was confirmed on 19 December 2010 that a captive wild mute swan (Cygnus olor) in Toyama prefecture was infected with HPAI. On 16 December 2010, a staff member of the Takaoka Old Castle Park Zoo found out the death of two mute swans in a moat. The local veterinary service centre in the prefecture confirmed a sample taken from the dead birds was influenza A virus positive by antigen-capture kits on the same day. On 19 December 2010, the National Institute of Animal Health affirmed by HI test that the case was due to influenza A virus sub-type H5 and found that the amino acid sequence of the connecting peptide of the haemagglutinin was the same as known highly pathogenic avian influenza. Neuraminidase inhibition assay are being carried out.
On 20 December 2010, the institute confirmed the case as HPAI because the isolate caused 75 per cent mortality in four-week-old chickens infected intravenously, the report continues. The isolate is a closely-related strain with the viruses isolated from faeces of migratory wild ducks in Hokkaido in October 2010 and the cases occurred in Shimane prefecture in November 2010. The zoo destroyed all captive wild birds kept in the moat for its own prevention on 18 December 2010. Although a total of four dead birds are found out, three were negative by antigen-capture kits.
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