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Highly pathogenic Avian Influenza in Hong Kong

by 5m Editor
11 August 2003, at 12:00am

HONG KONG - Follow-up report No. 2 (via OIE) on Avian Influenza in Hong Kong, China.

See also: 24th January 2003, 24th January 2003, 27th September 2002, 31st May 2002.

Information received on 4 August 2003 from the Director of Agriculture, Fisheries and Conservation Department (AFCD), Hong Kong:

End of previous report period: 14 January 2003 (see Disease Information, 16 [4], 23, dated 24 January 2003).

End of this report period: 4 August 2003.

A. In commercial poultry farms

A total of five outbreaks of avian influenza virus strain H5N1 were detected in Hong Kong during December 2002 and January 2003 in poultry markets and farms. No further cases have been detected since 31 January 2003.

Total number of birds in the outbreaks (final data):

present cases deaths destroyed slaughtered
155,300 12,800 12,800 84,650 0

Control measures applied:

- quarantine;

- depopulation or stamping out;

- ring vaccination;

- monitoring.

Surveillance:

There is an ongoing comprehensive avian influenza virus surveillance system conducted in local poultry farms, wholesale and retail poultry markets in Hong Kong.

Virus cultures for avian influenza detection are performed on samples from over 6,000 chickens and other poultry each month and on an ongoing basis.

B. In waterfowl and wildbirds

No further cases of H5N1 avian influenza have been detected in waterfowl parks or wild birds in Hong Kong.

Epidemiological details:

The viruses were all characterised as highly pathogenic H5N1 avian influenza viruses but the virus from the waterfowl and little egrets at Penfold Park were genetically distinct from the viruses from Kowloon Park and the other wild bird viruses.

Control measures applied:

Outbreak Ref. 1 (Penfold Park):

All remaining waterfowl were depopulated and the park was closed for disinfection. Ponds were disinfected with strong hypochlorite solution and the park was closed for one month.

The park has not been restocked with waterfowl.

Outbreak Ref. 2 (Kowloon Park):

All waterfowl and flamingos were placed in segregated quarantine facilities on-site away from the public and kept under treatment and close observation by veterinary staff.

Vaccinations using killed H5N2 avian influenza vaccines were given to resident waterfowl and flamingos. Sick birds were moved to an isolation area with separated individual pens.

All ponds were emptied and disinfected with hypochlorite solution on several occasions and staff followed strict biosecurity procedures.

The ponds were kept empty and the remaining birds were kept in quarantine for one month after the last H5N1 infected bird died on 2 January 2003.

The bird ponds have now reopened without any problems.

Outbreak Ref. 3 (New Territories):

The reclamation ponds had barrier lines strung across them, water levels were raised and feeding was stopped to discourage wild birds from entering this pond system to feed. This was continued for one month after the second grey heron died.

Surveillance:

After the outbreaks, a comprehensive surveillance system of wild birds and waterfowl ponds was conducted, including trapping and swabbing water birds at wetland areas around Hong Kong, faecal swabbing at roosting sites for egrets, faecal and environmental swabbing at all waterfowl and bird parks, and conducting necropsies and viral culture on dead wild bird submissions.


Source: OFFICE INTERNATIONAL DES EPIZOOTIES - 8th August 2003

5m Editor