A man whose brothers contracted bird flu has tested positive for the deadly virus, state-controlled media reported yesterday, as the World Health Organization (WHO) said it was investigating the possibility that one of the siblings passed the disease to another.
Vietnamese officials, however, said there was no evidence of human-to-human transmission in the cases. Health officials fear that the bird-flu virus could mutate into a form that can easily spread among people, sparking a global pandemic that could kill millions. There is no evidence that has occurred, however.
A 36-year-old man from northern Thai Binh province tested positive for the H5N1 strain of bird flu, the Pioneer newspaper quoted Vice Minister of Health Tran Chi Liem as saying.
His 47-year-old brother died on Jan. 10 from bird flu, while another brother, 42, was recovering in a hospital in Hanoi after also testing positive for the virus.
Since Dec. 30, a total of nine people have died of bird flu in Vietnam.
Health officials have said the family had eaten raw duck blood pudding late last month, linking their infections to poultry.
"From the H5N1 virus infected cases in Thai Binh recently, there is no evidence of human-to-human transmission," Liem said.
However, the WHO has not ruled out the possibility, because the middle brother cared for the elder sibling before he died.
But that alone would not raise the threat of a flu pandemic, said Peter Cordingley, spokesman for WHO's Western Pacific Regional Office in Manila. The UN agency has not yet confirmed reports of the third brother's infection.
Similar isolated cases of possible human-to-human transmission occurred in Hong Kong in 1997 and in Vietnam and Thailand last year, he said.
"WHO would not be unduly concerned about the public health implications of limited transmission of the virus from one person to another," he said.
"What would worry us is evidence of the virus being able to pass effectively between humans, thus setting off a chain of transmission. We have not seen this with the present cases, nor with previous ones," he said.
So far most human cases have been linked to contact with sick poultry.
"There is no indication that something is spreading quickly," said Hans Troedsson, the WHO representative in Vietnam.
"It's not that it has passed the threshold and opened the flood gates," he said.
Also in Vietnam, a 22-year-old woman in critical condition was being tested for the disease in Ho Chi Minh City after her younger brother died of bird flu, said Phan Van Tu, chief virologist at the city's Pasteur Institute.
Bird-flu outbreaks among poultry have been reported nationwide in Vietnam so far this year, killing or forcing the cull of more than 500,000 birds. Vietnamese authorities have ordered quarantines, stricter border controls and a ban on poultry from neighboring countries in an effort to battle the disease, fearing a repeat of last year.
Last year the virus surfaced in 10 Asian countries, killing or forcing the slaughter of more than 100 million birds.
The virus jumped to humans in Vietnam and Thailand, killing 29 and 12, respectively.