February 26, 2004

 

 

Study Confirms Human Transmission of Bird Flu Impossible

 

According to a study released by the New England Journal of Medicine, human transmission of the virulent bird flu strain is yet not possible.

 

An analysis of 10 of the first previously healthy patients to contract the lethal H5N1 strain of avian influenza A revealed an illness that killed eight of the children and young adults, according to a study to appear in the March 18 journal. Patients had some exposure to poultry or other birds, researchers said.

 

About 30 percent of Vietnam's estimated 260 million chickens are infected with avian flu, so the number of people affected is low by comparison, said Jeremy Farrar, the senior author of the paper and director of the Oxford University Research Group in Vietnam.

 

"I believe there is no evidence of human-to-human transmission during this outbreak and that's very reassuring," Farrar said in a telephone interview. "It must be fairly difficult to catch, but if you're unlucky enough to get it, it's a devastating illness."

 

Symptoms of H5N1 infection in people included fever, cough, diarrhea and trouble breathing; death usually occurred within two weeks. Most patients lived on family farms that raised poultry, handled chickens or ducks, or had other close contact with potentially infected birds, researchers said.

 

Investigators looked at patients at the National Hospital for Pediatrics in Hanoi and the hospital for Tropical Diseases in Ho Chi Minh City in December and January. The results were posted early on the journal's Web page.

 

Health officials are still concerned about whether the virulent avian influenza could mix with a human influenza virus in a host with both infections, creating a new version of the bug that retains its severity and can spread easily among humans, Farrar said. There's no evidence that process, called reassortment, has occurred, he said.

 

The first signs of such an outbreak would be infections among health-care workers and family members of infected patients, he said. Such a genetic mutation is rare, he said.

 

"It's not likely to happen tomorrow. It's not likely to happen at all," he said. "It only happened three times in the 20th century and we have no evidence it happened during this outbreak."

 

There have been 32 human cases of avian influenza infection in Vietnam and Thailand confirmed by the World Health Organization, including 22 deaths.

 

A critical next step is to fully fund public health and research facilities that can monitor, contain, treat and eventually prevent new and re-emerging infectious diseases, wrote Mark S. Klempner and Daniel S. Shapiro from Boston University School of Medicine in an editorial.

 

"Although emerging infectious diseases such as the avian influenza virus will continue to take small steps across the species barrier, the prize will be the avoidance of giant leaps to mankind," they said.