H5N1 outbreaks in Korea, Japan seen as linked

May 23, 2008 (CIDRAP News) – Two more wild swans infected with H5N1 avian influenza were found in Japan this week, and authorities in South Korea said H5N1 viruses found in chickens there closely matched an earlier isolate from swans in Japan.

The two latest infected swans were found "dead or weakened" on the shores of Lake Towada in Aomori prefecture in northern Japan, the prefectural government said yesterday, according to a Kyodo News report published today. Aomori is on the northern end of Honshu, Japan's main island.

In late April, four H5N1-infected swans were found on Lake Towada in Akita prefecture, which neighbors Aomori. In the ensuing 2 weeks, two more infected swans were found on Japan's northern island of Hokkaido.

In South Korea, the National Veterinary Research and Quarantine Service said this week that an H5N1 virus from chickens in South Jeolla province was 99.7% genetically identical to an isolate from the swans in Akita prefecture, according to a report from the newspaper Chosun Ilbo.

The finding suggests that the recent poultry outbreaks in South Korea may have stemmed from migratory birds, the story said. Kim Jae-Hong, a veterinary professor at Seoul National University, told the newspaper that viruses more than 99% identical are considered the same strain.

"This substantiates assumptions that migratory birds spread the virus on their way north in March and April after spending the winter in Southeast Asia," the story said. The report said similar observations were made when South Korea and Japan had avian flu outbreaks in 2003 and 2006.

South Korea has had 33 H5N1 outbreaks in poultry since Apr 1, leading to the culling of 663,034 birds, according to a report the country filed with the World Organization for Animal Health (OIE) on May 20.

Meanwhile, an avian flu alert was declared in a village on the Indonesian island of Sumatra after thousands of domestic birds died suddenly, according to a May 21 report in the Jakarta Post.

The alert affected Rimbo Mulyo village in the Tebo regency of Jambi province, the story said. The alert meant local people were required to report to the local health center every hour as a precaution. In addition, the regency health office set up a task force to conduct door-to-door health checks, the newspaper said.

In other developments, an international avian flu task force today called for greater international cooperation and establishment of an early warning system, according to a Deutsche Presse-Agentur report. The group spoke at a United Nations biodiversity conference in Bonn, Germany.

Robert Hepworth, secretary of the UN's Convention on Migratory Species, said the task force was "unequivocally opposed" to killing wild birds and destroying their habitats, according to the story.

See also:

OIE reports on 2008 outbreaks in Japan and Korea

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