
Laboratory tests showed samples from villagers in Sak Lek district to have the H5N1 virus.
According to the announcement of the department, about 30 chicken in Phichit have already died.
This is the second bird flu outbreak in Thailand this year. The first outbreak was confirmed on Thursday in lower northern Nakhon Sawan Province, which borders Phichit.
Meanwhile, tens of thousands of chickens in district found the virus in Nakhon Sawan were culled and disinfectant was sprayed throughout nearby areas.