Vietnamese authorities on Wednesday reported bird flu outbreaks in three more provinces, Vinh Phuc, Son La and Quang Ngai, bringing to 13 the number of cities and provinces affected in the most recent wave of illness that began a month ago.
Officials also said new but milder strains of bird flu have been discovered. Ngo Thanh Long, head of the epidemic diagnosis unit of Ho Chi Minh City's regional veterinary center, said strains of H3 and H4 subtypes were detected in poultry.
Long said random samples taken from 500 ducks in the Mekong Delta earlier this spring showed the new strains in two ducks. He said the strains are not considered virulent like the current H5N1 virus making its way through Asia.
"We cannot say that the H3 and H4 virus strains are spreading because its (presence) is minor and these strains of virus are not virulent," he said, adding the samples were sent to Australia for further research.
The Agriculture Ministry's Web site also reported another province, Bac Ninh, had been hit, but the animal health director there, Nguyen Van Lung, said he had no information on outbreaks for his region. Van Tan, the provincial animal health department director in central Quang Ngai, said authorities had culled 2,700 chickens, ducks and geese from four farms in one commune. Samples had tested positive for bird flu, he said.
In northern Vinh Phuc, about 100 chickens died in two farms and tests showed they had H5N1, said Duong Ngoc My, deputy director of the province's animal health department.
Culling of all poultry in the two infected areas will start Thursday, My said. The infected communes have been put under strict surveillance, he said.
Ha Dinh Nhien, deputy director of northern Son La's provincial animal health department, said veterinary officials culled more than 100 chickens in Moc Chau district and about 100 geese in Mai Son district after some of the birds sickened and died, reports the AP. I.L.