Bird Flu Spate Signals Easier Transmission

After smoldering through the summer and fall, avian flu has erupted again in Southeast Asia with 12 confirmed deaths since late December, the latest a 10-year-old Vietnamese girl who died Sunday.

Thailand has reported widespread outbreaks among farm poultry, and Vietnam, where all the fatalities have occurred in the last month, now counts bird or human infections in nearly half of its provinces.

The growing number of cases suggests that the virus may be mutating into a form that is more easily transmitted to and among humans, increasing the possibility of a pandemic.

“The situation in Southeast Asia right now is the most significant setup for a very serious public health crisis that I’ve seen in my 30 years in this business,” said Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. “We’re sitting on a time bomb.”

Vietnamese officials have struggled to contain the virus, deploying riot police at some checkpoints around Ho Chi Minh City to prevent an influx of infected birds during this month’s Lunar New Year celebrations.

The government has destroyed more than 1 million domestic poultry in an effort to control the outbreak. But the virus has become so widespread that the mass slaughter of birds has been abandoned in some infected areas.

Since July, about 1 million birds have died or been culled in Thailand, compared with about 40 million culled during the first few months of last year.

Authorities believe the virus has a natural reservoir in wild fowl, which continually reinfect domesticated flocks.

Fear of avian flu has become pervasive in the region. People in China, including Hong Kong, as well as in Japan and Thailand have begun to snap up supplies of Tamiflu, the one drug that is effective in suppressing the virus.

If Switzerland’s Hoffman-La Roche, Tamiflu’s only supplier, tripled production, it would still take it six months to make enough to supply 1 million people for five weeks, said Dr. Klaus Stohr, head of the World Health Organization’s global influenza program.

The strain of avian flu affecting Southeast Asia, known as H5N1, emerged in Hong Kong in 1997.

But it has spread rapidly in the last year, killing 44 people out of the 58 infected in Vietnam and Thailand, according to the WHO and the Vietnamese government.

Incidents in which the virus is believed to have been transmitted from one human to another have sparked the greatest concern.

One case involved three brothers near Hanoi, the Vietnamese capital. The first, Nguyen Huu Viet, 47, was admitted to a Hanoi hospital, suffering high fever, acute shortness of breath and a pounding headache. He died Jan. 9.

Soon after, his 42-year-old brother came down with similar symptoms, although he recovered. The third brother is under observation.

At first, Vietnamese public health authorities blamed the illnesses on raw duck blood pudding the brothers had shared.

But because the middle brother’s symptoms appeared a week after the normal 10-day incubation period for avian flu, experts now believe he contracted the disease while caring for his dying brother.

The case resembles that of a Thai family, in which a young girl who had touched sick birds apparently infected her mother. The mother lived separately and had no contact with infected fowl but later cared for the sick child, according to a report last week in the New England Journal of Medicine.

Both the girl and her mother died in September. Another caregiver, the child’s aunt, became critically ill but recovered.

Such cases suggest that the virus was passed between people during sustained contact. The fear is that the virus will mutate into a form that allows it to be transmitted with only casual contact, which would multiply the number of cases.

Southeast Asia is a fertile environment for mutation because frequent contact between densely packed human and poultry populations creates many opportunities for bird and human viruses to exchange genes.

Health authorities in South Korea, Japan, Taiwan, Indonesia, China and Malaysia, all of which battled bird flu last year, have reported no recent outbreaks. In Hong Kong, an infected migratory heron was found in January, but the city has protected commercial flocks.

Officials in Cambodia and Laos likewise have reported no new outbreaks, but monitoring is notoriously incomplete in those countries, said Henry L. Niman, an infectious-disease expert who maintains an Internet mailing list on avian flu.

“All these numbers are artificially low,” he said.

One sign that there may be unreported cases is the death of a 25-year-old Cambodian woman in Vietnam on Sunday. She had traveled to a Vietnamese border town seeking medical help.

Health officials have not confirmed that she had avian flu, but her symptoms were consistent with infection.