The affected localities include Haiphong, Hai Duong, Thai Nguyen, Ha Nam, Bac Giang, Bac Ninh, Quang Tri, Thanh Hoa, Soc Trang, Kien Giang, Ha Tinh, and Quang Nam.

Current adverse weather has reduced immunity in fowl while the many spring festivals have increased the chance of avian flu virus transmission, said the Vietnam Animal Health Department.

Provinces in the northern and central regions have not had effective vaccines against the mutated bird flu virus. Ha Tinh province has the highest rate of virus circulation – at 25 to 40 percent.

The shortage of disinfectants is another problem.

Meanwhile, many farmers raise fowl on a small scale, making epidemic control efforts more difficult.

Analysis of virus samples taken from epidemic hot spots shows that the new strain of A/H5N1 avian flu is circulating in northern, central coastal, and central highland provinces.

The old types of avian flu are still confined to southern provinces.

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