HANOI — Health officials said Saturday that the death of a boy from bird flu in Ho Chi Minh City was the first in southern Vietnam and expressed alarm that the outbreak had spread through much of Southeast Asia.
Five Vietnamese previously died of the disease, but all had fallen ill far to the north, outside Hanoi.
Officials say that despite the slaughter of millions of chickens in an effort to contain the disease, tests showed that the virulent H5N1 strain of avian influenza had spread from birds to people in Vietnam and Thailand.
There is no evidence that the disease is spreading from human to human, but experts worry that the virus could change its form or combine with another virus and cause a deadly worldwide epidemic.
"Our greatest fear is that the virus will change itself," said Robert Dietz, spokesman for the World Health Organization in Vietnam. "Because this virus is now so widespread across Southeast Asia, there is more opportunity for it to change into something that can be transmitted between human beings."
Officials say the bird flu has the potential to be far more serious than SARS, or severe acute respiratory syndrome, which killed more than 700 people and caused millions of dollars in economic losses when it swept through the region a year ago.
The avian virus apparently had months to spread among chickens in Vietnam and Thailand before the governments of the two countries acknowledged its presence and began taking steps to control it. Officials say that of the six confirmed deaths from avian flu in Vietnam, five have been children.
The latest death, that of a boy in Ho Chi Minh City, occurred Thursday, the WHO said. Tests showed that a young girl in Ho Chi Minh City also had contracted the disease. She is hospitalized in critical but stable condition.
Health officials are investigating additional suspected cases. Experts fear that there may be more cases in rural areas of Vietnam where medical care and testing to detect avian flu are limited.
In Thailand, after weeks of denying the presence of the virus, officials confirmed Friday that two boys had contracted the disease and three other cases were suspected.
The announcement prompted charges from government critics that officials had attempted to cover up the disease for fear of harming the poultry industry. Countries in Europe and Asia immediately banned the importation of chickens from Thailand.
