The Vietnamese crew member feared to have died of bird flu while his boat was en route to Thailand was very unlikely to have had the virus, the Public Health Ministry said yesterday, citing a preliminary disease investigation.

The 51-year-old man probably died from heart problems, said Public Health deputy permanent secretary Dr Somyos Charoensak.

The ministry's investigation unit had gone straight to the vessel as soon as it anchored at a port in Samut Prakan's Phra Pradaeng district, Somyos said.

The preliminary investigation showed the man, who worked as a welder for a Vietnamese commercial boat hired by a Thai company to transport goods between Thailand and Indonesia, had not been in contact with any sick poultry and did not have a fever before he died on the way back to Thailand, he said.

Before he died suddenly on January 14 while at sea, the man reportedly suffered severe fatigue and wheezing - indicating symptoms of heart disease, Somyos said.

Moreover, as a welder, the man didn't leave the vessel while it was anchored in Indonesia, he said.

"Regarding his history and symptoms, this is not bird flu," Somyos said, adding that the autopsy results were expected to be known within a week.

The remaining 24 crew members travelling with the man were all in good health.

In Phitsanulok, where H5N1 infections were recently confirmed in free-range ducks, health officers continued to monitor the situation closely and no case of suspected bird flu had been detected so far, said Somyos.

The lab results of two patients, a 29-year-old man and 13-year-old boy from the same sub-district where the infected ducks were found, confirmed they had human influenza - not bird flu, he said.

Arthit Khwankhom

 The Nation