BANGKOK (AFP) - Thailand was scrambling to determine whether bird flu struck five people in a northern province as the World Health Organisation expressed concern that human-to-human transmission of the lethal virus had occurred.
An intense investigation has focused on Kamphaeng Phet province, where a boy and a girl who died this month of severe pneumonia after coming into contact with dying chickens are listed as suspect bird flu cases.
The 11-year-old girl's mother, who lived near Bangkok but traveled north to visit her daughter in hospital and then attend her funeral, returned to the Thai capital where she too fell ill and died. Her death is also on the suspect list.
Laboratory tests on the three fatalities, as well as on the girl's aunt and the aunt's son who are hospitalised with severe pneumonia, were being conducted to detect the virus that has already killed 28 people in Asia since December.
WHO's acting Thailand representative, Kamara Rai, told AFP Saturday after studying information from Kamphaeng Phet that it appeared the mother and the aunt not come into contact with sick chickens.
"From the existing data ... we are suspecting human-to-human transmission," he said.
Health ministry spokeswoman Nitaya Chanruang Mahabhol also said: "After all the investigation it has not been shown that she (that aunt) was in close contact with dying chickens."
The WHO fears the lethal H5N1 strain could mutate into a highly contagious form and trigger a global human flu pandemic.
Results from an initial laboratory test on the aunt have come back negative, Health Minister Sudarat Keyuraphan has said, but a second confirmation test on the aunt and further tests on the others were being conducted and results could be known by Monday.
Sudarat has downplayed the threat of human-to-human transmission but Thailand has gone on full alert as a precautionary measure.
The health ministry has ordered a 1,000-strong team to fan out across Kamphaeng Phet searching for sick or dead fowl and demanding anybody with flu-like symptoms seek immediate medical attention, Nitaya said.
Similar measures have been taken in most provinces including the 30 which have seen 149 confirmed outbreaks of bird flu in chickens and other birds since the second wave of bird flu began in early July.
Charal Trinvuthipong, director general of the disease control department, visited the aunt and her son in hospital Sunday and said they were recovering. "The child has improved quite dramatically and he is due to be discharged soon," Nitaya quoted Charal as saying.
Rai said that while the WHO was still concerned the virus may have mutated, the possibility that the girl passed the virus directly to her mother or aunt was "remote".
"But it is good Thailand has prepared for the worst, however remote the possibility is. Thailand's early announcement to the public (about the possible human transmission) is to be commended."
Nitaya said the WHO's concerns were valid. "We are always operating on those hypotheses, that it could occur here, but we cannot say positively until we have scientific proof."