# 2849
When the story first broke, we were told that the bird flu outbreak on a quail farm near Toyohashi, Japan involved an H7 virus.
Today, we learn that the virus is the H7N6 strain.
Influenza `A' viruses are categorized by their H (Hemagglutinin) and N (Neuraminidase) surface glycoproteins.
Scientists have identified 16 different Hemagglutinin and 9 different Neuraminidase proteins. Theoretically, they could combine to produce 144 different flu strains.
In practice, there are currently only 3 strains of `human adapted' influenza `A' viruses in wide circulation; H1N1, H1N2, and H3N2.
In contrast, there are more than a dozen avian flu viruses commonly found in poultry and wild birds. While we don't often hear about the more obscure, low pathogenic avian viruses, they are out there.
H7 viruses have been associated with human infection on rare occasion, most often producing only mild symptoms.
This summary from the CDC.
Influenza A H7
Nine potential subtypes of H7 are known. H7 infection in humans is rare but can occur among persons who have direct contact with infected birds. Symptoms may include conjunctivitis and/or upper respiratory symptoms. H7 viruses have been associated with both LPAI (e.g., H7N2, H7N7) and HPAI (e.g., H7N3, H7N7), and have caused mild to severe and fatal illness in humans.
This report from AFP.
Japan quail farm bird flu 'not H5N1': govt
March 1st, 2009
The Japanese agriculture ministry said Sunday an outbreak of bird flu at a quail farm was not H5N1, the form of the disease that can be deadly to humans.
Government scientists said the disease in central Japan was the less-virulent H7N6 strain.
Workers sanitised the farm in Aichi prefecture Sunday and prepared a large trench to bury most of the 320,000 birds there.
The ministry announced the outbreak Friday, adding that the virus was weak in its toxicity and had not killed any animals. It added that no humans had been infected.
In April and May last year several dead swans tested positive for the H5N1 strain of bird flu in Hokkaido, northern Japan.
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