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Drop in virus mortality rate portends new danger

Page 2 of 2 -- Last year, US researchers reported that ducks in Southeast Asia had begun carrying the bird flu virus without showing symptoms. Now, scientists in Vietnam have found numerous asymptomatic cases in the country's vast chicken population, according to Nguyen Tran Hien, director of the National Institute of Hygiene and Epidemiology.

''It seems that the virus may adapt in humans and in poultry a little bit; therefore, the symptoms are not as severe as before," Hien said. ''Also, the transmission may be faster and easier."

Moreover, the existing virus strain is not the only threat. Each human case also presents a chance for the bird flu virus to swap genetic material with an ordinary flu bug if the person becomes infected with both strains at the same time, potentially creating a new hybrid that is highly lethal and even easier to catch.

''We are concerned that if the virus is changing, maybe a new virus is coming in the future," Hien said.

Vietnamese and international health officials say they are confident that the mortality rate has dropped, but are not sure by how much. Better screening and wider public awareness of bird flu could mean that health workers are catching and recovering from milder cases that would have gone unreported a year ago.

WHO officials have complained, however, that Vietnam is reluctant to provide detailed information about human cases. Senior Health Ministry officials respond that reports are provided in accord with national regulations.

The question now is whether bird flu in Vietnam has begun passing among humans.

If it has, Nguyen Duc Tinh, a nurse who treated Tuan at the Thai Thuy district health center and fell sick with bird flu soon after, would be a likely case. Tinh, 26, said he had no contact with poultry for a month beforehand despite government accounts attributing his illness to infected chickens.

Tinh said he was the hospital staff member who had the closest contact with Tuan during his brief stay at the health center, taking his blood pressure and temperature, giving him injections, and helping him walk. Within a week, Tinh had developed muscle aches and a high fever, symptoms of what he believed was a common flu. But when the fever subsided and then returned two days later, he grew alarmed.

''Then I suspected I had bird flu," he recalled, his brown eyes widening. ''I was really, really afraid of dying."

But just two weeks after joining Tuan in the Hanoi hospital, Tinh was discharged and went back to his village.

''I had lost hope when the fever came a second time," he said. 

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