May 1, 2006 (CIDRAP News) – A mild form of avian influenza virus found on three poultry farms in Britain has infected one farm worker and prompted culls on the farms.
Preliminary tests showed that the virus is a low-pathogenic H7N3 strain, according to a news release Apr 29 from the British Department of Environment, Food and Rural Affairs (DEFRA). Confirmatory tests are being conducted by the Veterinary Laboratories Agency, and results should be available in a week, DEFRA said.
One poultry worker developed conjunctivitis from his exposure to the virus, according to an Apr 28 report by Agence France-Presse (AFP). He did not require hospitalization, the story said.
Three workers at another farm who showed signs of conjunctivitis do not have H7N3 infections, BBC News reported today. The farms are in Dereham, in eastern England.
DEFRA noted that in almost all cases of human H7 infection to date, the virus, in both low- and highly pathogenic forms, has caused only mild disease. "Therefore at this stage this is a virus which only has extremely limited implications for human disease," the agency said.
The farms involved were Norfolk Road Farm, Mowles Manor Farm, and Witford Lodge farm (where the first cases were found), BBC reported. Another BBC story today said that chickens at all three farms—totaling about 50,000 birds—have been destroyed.
In addition to the culling, a 1-km restricted zone was created around each farm, DEFRA said on Apr 29. That zone restricts movement of poultry, poultry products, and eggs, AFP said.
"The State Veterinary Service is tracing movements and contacts, the necessary surveillance and all appropriate worker protection measures have been put in place," DEFRA noted.
The source of the virus is thought to be another farm or wild birds, Debby Reynolds, DEFRA chief veterinary officer, said in the news release.
DEFRA said H7N3 was last reported in Britain in 1979. But the European Union Centre for Disease Prevention and Control said today that another person in Britain contracted conjunctivitis attributed to a low-pathogenic H7N3 virus in the 1990s.
A major poultry outbreak of H7N7 avian flu occurred in the Netherlands in 2003. That outbreak led to 89 human infections, most of which were mild, but one veterinarian died.
Britain has been on alert for avian flu since the deadly H5N1 virus was discovered in a wild swan found on the east coast of Scotland in late March. No further cases have turned up in the country since then.