A veterinary worker sanitizes poultry in Hanoi, capital of Vietnam, April 11, 2013. A 4-year-old boy died of avian influenza strain H5N1 in Vietnam's southern Dong Thap province on Tuesday, in a first case of death by the virus in over a year in Vietnam, local media reported on Wednesday. (Xinhua/VNA)

Veterinary workers take samples from poultry for tests in Hanoi, capital of Vietnam, April 11, 2013. A 4-year-old boy died of avian influenza strain H5N1 in Vietnam's southern Dong Thap province on Tuesday, in a first case of death by the virus in over a year in Vietnam, local media reported on Wednesday. (Xinhua/VNA)