Jun 5, 2008 (CIDRAP News) – The avian influenza virus that struck chickens on a farm in England this week has been identified as highly pathogenic H7N7 and is probably related to viruses that have sometimes surfaced in other European countries, British officials said today.
"Preliminary analysis . . . indicates that this H7N7 strain is likely to be related to viruses which have occasionally been detected in domestic poultry and wild birds elsewhere in Europe," the United Kingdom Department for Environment, Food, and Rural Affairs (DEFRA) said in a statement.
DEFRA said further laboratory tests were under way. The statement did not suggest how closely related the virus may be to the H7N7 strain that caused a series of major poultry outbreaks and forced the destruction of millions of birds in the Netherlands in 2003. That virus also infected at least 89 people, causing mild conjunctivitis in most cases but killing a veterinarian.
First reported Jun 3, the latest outbreak occurred on a farm near Banbury, Oxfordshire, about 80 miles northwest of London. A flock of 25,000 chickens is being culled.
"The Health Protection Agency has advised that H7N7 avian flu remains largely a disease of birds and the risk to human health is low," a DEFRA statement said. The agency set up protection and surveillance zones around the outbreak site and said a full epidemiologic investigation was under way.
Richard Court, the owner of the farm, said the source of the outbreak was unknown, according to British newspaper reports today.
The United Kingdom has had some previous avian flu outbreaks involving H7 viruses, but World Organization for Animal Health (OIE) records show no previous H7N7 outbreaks in the country.
In May 2007, a low-pathogenic H7N2 virus surfaced on a chicken farm in northern Wales. Four people who had contact with infected birds tested positive for the virus, but symptoms were mild, according to reports at the time.
About a year earlier, in April 2006, a low-pathogenic H7N3 virus turned up on three farms in Dereham, northeast of London. One farm worker was found to be infected.
Jun 5 DEFRA statement
OIE reports on 2008 H7N7 outbreak