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The importance of having a poultry surveillance system and the need for segregation of waterfowl from other poultry have been clearly demonstrated by the isolation of an H5 influenza virus from a stall in Western Wholesale Poultry Market (WWPM).

A spokesman for the Agriculture and Fisheries Department (AFD) confirmed today (Friday) that an H5N1 virus was isolated recently from cage swabs taken from a stall in WWPM.

AFD immediately sent the virus to local and international laboratories for further characterisation. Analysis showed that it was a distant relative of the H5N1 virus found in 1997.

He emphasized that waterfowls are known carriers of influenza viruses and this was the rationale for introducing the strict segregation policy for waterfowls and other poultry last year.

The policy requires waterfowls to be segregated from other birds throughout production and marketing, and live waterfowls are not allowed to be sold in retail markets.

The spokesman said: "This finding has shown how vital this system is in preventing the spread of H5 virus to chickens.

"H5 virus had not been isolated previously since importation of birds resumed in early 1998. This is the only case that H5 virus was isolated from swabs collected in WWPM.

"The successful isolation also demonstrates that AFD's stringent import control and monitoring systems are working well. Testing and regular monitoring of birds at all levels of production - local farms, imported birds and wholesale and retail markets will continue as a regular measure," the spokesman said.

The virus isolated had not caused any illness in birds in WWPM.

The spokesman said imported waterfowls were considered to be the likely source of the virus and AFD had advised Mainland quarantine officials of the findings.

"Our Mainland counterparts are investigating their duck and goose farms and will suspend supply of birds to Hong Kong from any farm showing signs of infection."

In Hong Kong, AFD will continue with its regular cleansing and disinfection of the WWPM.

Health staff from the Department of Health (DH) visited the market following the incident and found none of the workers reporting any illness.

DH agreed that since waterfowls are natural carriers of the virus, isolation of H5 virus in this incident posed no public health risk. However it fully demonstrates the importance of the segregation policy.

DH had informed the World Health Organisation of the isolation of the virus.

End/Friday, March 26, 1999

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