BEIJING, Jan. 4 (UPI) -- Chickens showed symptoms of avian flu at a farm in a village in the province of Guizhou in China where 8,500 chickens died in December, officials say.
Officials at the Ministry of Agriculture in China said the fowl died Dec. 27 and the National Avian Influenza Reference Laboratory confirmed the epidemic was H5N1 bird flu after testing samples collected at the farm, China's official Xinhua News Agency reported.
The Ministry of Agriculture said local authorities sealed off and sterilized the infected area. More than 23,067 chickens were culled and disposed of to prevent the disease from spreading, agriculture officials said.
Bird flu, or avian influenza, is a contagious disease of animal origin by type A strains of the influenza virus that normally infect only birds and, less commonly, pigs. It can be fatal to humans, the Ministry of Agriculture said.
The infection can cause a wide spectrum of symptoms in birds, ranging from mild illness, which may pass unnoticed, to a rapidly fatal disease that can cause severe epidemics, officials at the World Health Organization said.
"Avian influenza viruses do not normally infect humans. However, there have been instances of certain highly pathogenic strains causing severe respiratory disease in humans," WHO said. "In most cases, the people infected had been in close contact with infected poultry or with objects contaminated by their feces. Nevertheless, there is concern that the virus could mutate to become more easily transmissible between humans, raising the possibility of an influenza pandemic."