Tests confirm H5N1 in Hong Kong outbreak

Dec 11, 2008 (CIDRAP News) – Agriculture officials in Hong Kong today confirmed that the avian influenza virus that recently hit a large commercial chicken farm was the lethal H5N1 strain, as authorities vowed to explore potential protection gaps in the poultry vaccine and the possibility that smuggled eggs might be a source of the virus.

Jolly Choi, spokeswoman for Hong Kong's agriculture, fisheries, and conservation department said earlier tests on Dec 9 were positive for an H5 virus, but further testing showed that three chickens found dead on the farm had the H5N1 subtype, according to a report today from the Associated Press.

Meanwhile, York Chow, Hong Kong's secretary for food and health, told reporters at a press conference yesterday that experts are focusing on two lines of investigation: a possible biosecurity lapse at the farm and if a change in the circulating virus has hobbled Hong Kong's poultry vaccine.

The outbreak, China's first on a farm since 2003, prompted the culling of more than 80,000 birds and restrictions on poultry imports.

Chow said Hong Kong been using an H5N2 vaccine manufactured in the Netherlands since 2003. "Over the last few years it has been proven to be effective, but we also think that because the change of the virus, we might have to look for a more appropriate vaccine," he said in a government press release.

The Chinese mainland has been using H5N1 vaccine for poultry over the past few years, which is modified periodically, Chow said, adding that veterinary officials have contacted mainland authorities to explore if a switch to the H5N1 vaccine would be more protective. He said that government officials would also be seeking guidance from experts at Hong Kong University, where vaccine studies in poultry have already been under way since June.

So far there is no evidence that the virus has spread to other farms, Chow said in the statement. Investigators have collected samples from farms to conduct polymerase chain reaction (PCR) testing, and the results should be available in a day or two.

In other developments, poultry trade representatives in Hong Kong said today that smuggled fertilized eggs from China could be the source of the recent H5N1 outbreak, according to a report today from Agence France-Presse (AFP).

The Hong Kong Poultry Wholesalers Association said smuggling has become more common since the government banned the import of 1-day-old chickens from China as an H5N1 prevention measure earlier this year, the AFP report said.

The South China Morning Post reported today that the eggs, ostensibly imported as food, contain potentially infected embryos that are less than a week from hatching, according to AFP. However, the owner of the farm that was struck by the H5N1 virus denied having smuggled any fertilized eggs from China, the report said.

Elsewhere, health ministry officials in India said today that the H5N1 virus has now spread to six of 27 districts in Assam state, according to a report from Indo-Asian News Service (IANS).

Parthajyoti Gogoi, a health ministry official, told IANS that more than 200,000 chickens and ducks have been culled since the outbreak was first detected 2 weeks ago. The culling activities have affected 200 villages in Kamrup (Metro), Kamrup (Rural), Dibrugarh, Nalbari, Barpeta, and Chirang districts.

He said teams of doctors and paramedics are taking measures to prevent human H5N1 infections, the report said.

See also:

Dec 10 Hong Kong government press conference transcript

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