Japan Confirms Outbreak of HPAI

JAPAN - The authorities have confirmed that the earlier outbreak of bird flu on a layer farm was caused by the H5N1 sub-type of the highly pathogenic avian influenza (HPAI) virus.

3 December 2010

3 minute read

Asia

The veterinary authorities sent an Immediate Notification dated 2 December to the World Organisation from Animal Health (OIE).

The report confirms that the outbreak of bird flu at a layer farm at Yasugi city in Shimane prefecture in the south-west of Honshu was caused by the H5N1 HPAI virus. The outbreak started on 27 November. IN total 57 birds died but the remaining 21,549 layers have been destroyed.

According to the report, the outbreak of HPAI was confirmed on 2 December 2010 in Shimane prefecture. The previous outbreak of HPAI in Japan started in April 2008. The event has been contained in the affected farm by control measures including stamping-out and movement restrictions.

On 29 November 2010, a local veterinary officer visited the farm immediately after notification from the owner. Although no remarkable increase of the mortality was recognized, the local veterinary service centre in the prefecture confirmed that three out of five samples taken from dead birds were influenza A virus positive by antigen-capture kits. On the same day, the centre confirmed the sub-type was H5 by RT-PCR test.

On 1 December 2010, the National Institute of Animal Health affirmed an isolate was due to influenza A virus subtype H5 by HI test.

On 2 December 2010, the institute confirmed the cases as HPAI because the isolate caused 75 per cent mortality in four-week-old chickens infected intravenously, and the amino acid sequence of the connecting peptide of the haemagglutinin was the same as that observed for the highly pathogenic avian influenza viruses isolated from faeces of wild ducks in Hokkaido in October 2008.

Killing of the susceptible animals started on 30 November 2010 and was completed on 2 December 2010. Incineration of the carcasses and disinfection of the farm are continuing.

A movement restriction zone was established within 10km around the affected farm on 29 November 2010. In addition, the traffic around the affected farm was restricted. There are four poultry farms in addition to the affected farm in the zone. They are also under surveillance. A total of 13 disinfection stations were established in and around the restriction zone.