An official sprays disinfectant on a truck loaded with live chickens at a checkpoint in Songkhla’s Rattaphum district following reports of an outbreak of bird flu in central Thailand.

 A 43-year-old Ayutthaya free-range duck herder suspected to have contracted bird flu has tested negative for the deadly H5N1 strain of virus, the Public Health Ministry said yesterday.

Laboratory test results released yesterday calmed fears about another human infection after about 100 of the man's birds died and he, too, fell ill with flu-like symptoms. He has been isolated and treated at a hospital in Bang Pahan where doctors describe his condition as good, according to Medical Science Department director-general Dr Paijit Warachit.

Checks on residents near the man's home will continue for 10 days as stipulated by the ministry, he said.

Since January 1, 111 patients in 31 provinces have been tested for the bird-flu virus. None have tested positive, Paijit said.

He said the volume of tests for the virus in humans was "not particularly high" and on Saturday his laboratory ran 19 checks.

Ayutthaya Governor Cherdphan na Songkhla said all 16 districts of the province had been declared disaster areas.

This allows livestock authorities to investigate any suspected case of bird flu in animals and cull those infected.

He called for calm, particularly in Bang Pahan, but warned the disease may be in water sources. Experts are checking these.

Precautionary disinfecting of areas known to be frequented by migratory birds is under way.

Meanwhile, in Nong Khai, where the deaths of about 200 chickens were reported, officials slaughtered 2,000 birds yesterday and surveillance has been stepped up, particularly in Si Chiang Mai district.

With news the virus has been detected in some parts of the country, Nakhon Ratchasima Zoo is now feeding its animals pork and beef instead of raw chicken.

The zoo's carnivores normally consume about 1,400 chickens each day, director Bunyad Intarasuwan said.