Influenza A (H7N3) virus
H7N3 is a subtype of the species Influenza A virus (sometimes called bird flu virus). In North America, the presence of H7N3 was confirmed at several poultry farms in British Columbia in February 2004. As of April 2004, 18 farms had been quarantined to halt the spread of the virus. Two cases of humans infected with it have been confirmed in that region. Symptoms included conjunctivitis and mild influenza-like illness. Both fully recovered.
"The H7N3 strain was first detected in turkeys in Britain in 1963 and made one of its last known appearances in poultry in Canada in April and May 2004, according to the WHO and World Organisation for Animal Health. An outbreak of the less virulent H5N2 strain of bird flu in Taiwan in 2004 led to the culling of hundreds of thousands of fowl." "Taiwan found a highly pathogenic strain of avian flu, H7N3, in droppings left by a migratory bird and is carrying out tests to see whether the virus has spread to nearby poultry farms, the agriculture department said 14 November 2005."
For the first time since 1979, H7N3 was found in the UK in April 2006. It infected birds and one poultry worker (whose only symptom was conjunctivitis) in a Norfolk, England Witford Lodge Farm. Antiviral Tamiflu was administered to poultry workers on the farm as a precautionary measure. 35,000 chickens will be culled in the infected farm and a 1 kilometre exclusion zone has been placed.
In September 27, 2007 another outbreak of H7N3 was detected in a poultry operation in Saskatchewan, Canada. The Canadian Food Inspection Agency has announced the euthanization of the flock, and the disinfection of all building, materials and equipment in contact with the birds or their droppings.
In June, 2012, an outbreak was found on about 10 farms in Jalisco, Mexico. Of the over 6 million birds checked, 1.7 million were found to be sick. The area primarily produces layers and supplies eggs. The virus is not transmitted from hens to their eggs.