CHINA - Human infections with influenza-A H7 viruses, a virus group that normally circulates among birds, have been rare until now, according to a researcher at Harbin Veterinary Research Institute under the Chinese Academy of Agricultural Sciences.
Tian Guobin said that in addition to human infections with H7N9 - one subgroup among the larger group of H7 viruses recently reported from China - some H7 strains, such as H7N7, H7N3 and H7N2, have in the past infected humans in other countries, including the UK, the US, the Netherlands and Canada.
The H7N9 virus was first isolated in turkeys in the US state of Minnesota in 1988, he said.
Since then, the virus has been found in ducks, geese, guinea fowls and wild birds in Sweden, the Czech Republic, Spain, Mongolia, South Korea and elsewhere, according to the institute.
But humans seemed unaffected by the H7N9 virus until recently in China.
The world's first bird flu outbreak was in Italy in 1878.
All poultry and wild birds are likely to be infected with bird flu virus, Tian said.
So far, about 90 species of birds worldwide have been found to carry bird flu viruses.
These viruses have also been found in seals, whales, tigers, horses and pigs, according to the institute.
Bird flu viruses cannot be transmitted by consuming well-cooked poultry, eggs and related products because high temperatures kill the virus, Tian said.
But people should keep raw food separate from cooked food to avoid spreading any viruses from raw food, he said.
Tian urged local poultry farms to strengthen biosecurity measures, which is essential for keeping farms disease-free.