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H5N2 Bird Flu in Japan
June 25, 2005
>> The H5N2-type avian influenza virus has been detected in chickens at a poultry farm in Mitsukaido, east Japan's Ibaraki Prefecture, the Agriculture, Forestry and Fisheries Ministry announced Sunday.
The ministry confirmed the infection of chickens with the virus at the farm after about 430 of its 25,000 chickens died between March and May. <<
The above description of the H5N2 bird flu isolate in Japan suggests it will be similar to the H5N2 isolated in Taiwan at the end of 2003 and the H5N2 infected ducks in South Korea at the end of 2004.
Most of the H5N2 sequences at GenBank are from North America. Like all of the H5N1 isolates from 2005, there are no sequences at GenBank representing the H5N2 outbreak in South Korea. However, there is one H5N2 isolate, A/chicken/Taiwan/1209/03(H5N2), representing the outbreak in Taiwan at the beginning of last season. Both sequences (H and N) are similar to H5N2 sequences from chickens in Mexico from an outbreak in the mid 90's. That outbreak included isolates with a additional six nucleotides at the HA cleavage site, which created an HPAI (High Pathogenic Avian Influence) site. However, these additional six nucleotides were not in the isolated from Taiwan, which was classified as a LPAI (Low Pathogenic Avian Influenza).
Although it is possible that the H5N2 in Japan is a reassortant, with an H5 from H5N1 and an H2 from H3N2 or H9N2 isolates that have been detected in live markets in South Korea in 2003, it is much more likely that the H5N2 in Japan is similar to the H5N2 in Taiwan, based on the small number of birds that died.
H5N2 infections of humans has not been reported.