BANGKOK, (AFP) - Thai health authorities are on full bird flu alert after three deaths and an illness suspected of being caused by the virus sparked concern that it may have been transmitted between humans, officials said.
A mother and her 11-year-old daughter, as well as a 13-year-old boy from another family, all died of bird-flu-like symptoms in the past two weeks, while the aunt who cared for the girl is hospitalised with severe pneumonia.
All cases are being treated as suspected bird flu and laboratory tests are being conducted to determine if they carried the virus.
"As of now, health ministry officials are on full alert, regardless if an area is a bird flu outbreak zone or not," health ministry spokeswoman Nitaya Chanruang Mahabhol told AFP.
"Officials are being told to be 100 percent vigilant about bird flu."
Avian influenza has killed at least 28 people this year -- 19 in Vietnam and nine in Thailand -- in two waves of outbreaks that have swept Asia and caused the death or culling of more than 100 million chickens and birds.
The World Health Organisation fears the lethal H5N1 strain could mutate into a highly contagious form and trigger the next pandemic.
Health Minister Sudarat Keyuraphan and others have acknowledged that concern has mounted that the mother, identified by her first name Pranee, and the girl's aunt Pranom may have contracted bird flu directly from the girl as it had yet to be confirmed the women were in contact with chickens.
Sudarat sought to downplay the fears, however, stressing that initial tests on the aunt showed no bird flu.
"Initial test results (on the aunt) were negative, so at the moment it's a relief for the ministry concerning whether the virus has jumped from human to human or not," Sudarat said.
"But we still need to double check a final test."
Sudarat said she believed the aunt and mother might have been exposed to sick chickens at the aunt's house.
But Charal Trinvudhipong, the director of the disease control department, was quoted in a Thai daily as saying the mother and aunt had "no history of direct contact with chickens".
"If we find the virus in Pranom, and both Pranom and Pranee had no direct contact with the chickens and merely tended to their sick girl, it could mean that the virus jumped from human to human," Matichon newspaper quoted him as saying.
The girl and the aunt with whom she lived, died in Khanuworalaksaburi district of northern Thailand's Khampaeng Phet province, where their households kept chickens that fell ill and died.
The boy, whose home also raised chickens, died in another village in the district.
Officials said the girl's mother lived near Bangkok, but traveled north to be with her sick daughter and then attended her funeral before returning home, where she fell ill and died at a hospital.