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Dark side to good news on bird flu

More than a year after avian flu emerged in East Asia, killing more than two-thirds of the people with confirmed cases, Vietnamese doctors are reporting that the mortality rate in their country has dropped substantially, raising the possibility the virus could spread more easily and cause a global pandemic.
/ Source: a href="" linktype="External" resizable="true" status="true" scrollbars="true">The Washington Post</a

Nguyen Sy Tuan can barely talk. His wasted frame is tucked beneath a thin white sheet on the hospital cot. His cheeks are sunken and his bulging eyes stare blankly at the ceiling. But the young man has begun to eat rice again and can finally breathe without a mechanical ventilator, a dramatic turnaround for a bird flu patient whose doctors had assumed would die.

More than a year after avian influenza emerged in East Asia, killing more than two-thirds of the people with confirmed cases, Vietnamese doctors are reporting that the mortality rate in their country has dropped substantially.

An ominous turn
But while this is good news for survivors, it could mean the outbreak of bird flu in Southeast Asia is taking an ominous turn. If a disease quickly kills almost everyone it infects, it has little chance of spreading very far, according to international health experts. The less lethal bird flu becomes, they say, the more likely it is to develop into the global pandemic they fear, potentially killing tens of millions of people.

"The virus could be adapting to humans," said Peter Horby, an epidemiologist with the World Health Organization in Hanoi, the Vietnamese capital. "There's a number of indications it could be moving toward a more dangerous virus."

The mortality rate for bird flu in Vietnam this year is about 35 percent, almost exactly half that of last year, according to Health Ministry statistics. The mortality rate of the 1918 Spanish flu pandemic, by comparison, was less than 5 percent, but the outbreak killed an estimated 40 million people worldwide.

Officials said the drop in the bird flu mortality rate was more marked in northern Vietnam than in the south. While the virus in southern Vietnam is still killing at the same pace as last year, the rate in the area around Hanoi and elsewhere in the north has dropped from that level to as low as 20 percent. Vietnamese health experts said their suspicion that the disease is shifting is further supported by preliminary research showing a genetic change in the virus in the north resulting in the production of a protein with one fewer amino acids than in the south.

A virus on the move?
Health researchers believe that nearly all the 52 people known to have died of bird flu in Southeast Asia caught the virus from infected poultry. But with more clusters of cases among families reported in Vietnam this year — including that of Tuan, his sister and their grandfather — experts say they are growing increasingly suspicious that the disease has begun passing from one human to another.

Also worrying is the discovery of at least five cases, including that of Tuan's grandfather, in which people tested positive for bird flu but showed no symptoms. This could make it more difficult to contain an epidemic because people could transmit the disease without anyone realizing it.

Last year, U.S. 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.

Two survivors
Tuan, 21, left his home among the glistening paddies of northern Vietnam's rice-growing region more than a year ago for Haiphong, on the coast, where he worked harvesting seaweed for use in local cuisine. In early February, he returned to his family's simple brick house to celebrate the Tet New Year holiday.

According to his doctors, Tuan slaughtered a chicken for a festival meal, cutting its neck while his 14-year-old sister clutched the wings and legs. The bird was likely infected, and soon the siblings were, too.

Tuan started running a high fever about four days later, his wizened father recounted between puffs on a traditional bowl pipe in the family's one-room home.

When Tuan started coughing and had trouble breathing, he was taken to the local health center in Thai Thuy district. X-rays showed a white smudge on his left lung. Tuan was transferred after less than a day to a larger hospital in the provincial capital. There, the doctors concluded he had contracted the H5N1 strain of avian influenza and immediately rushed him to the tropical disease institute at Hanoi's Bach Mai Hospital.

By the time he arrived, X-rays showed, the white smudge had clouded the entire lung. Soon it took over the other one as well. "From one day to the next day, it spread very quickly," recalled Nguyen Thi Tuong Van, deputy director of the Bach Mai intensive care unit.

After 10 days, with his breathing failing, the doctors inserted a tube in Tuan's throat and put him on a ventilator. The infection spread to his kidneys and liver.

"We thought it was very likely the bird flu would kill him," Van said. "Then, when it seemed the situation couldn't get much worse, it started to get better. Two weeks later, when he didn't die, I thought maybe we could cure him."

Tuan's sister, Nguyen Thi Ngoan, a tall, mischievous 14-year-old with large black eyes, fell sick several days after her brother and also recovered.

At the district health center, X-rays revealed her lungs were clear, but a subsequent blood test was positive for bird flu. She was transferred to the Hanoi hospital, where she lay in the cot beside her brother and her temperature soared to 105 degrees.

But the fever broke after four days and returned to normal within two weeks, her doctors said. Ngoan went back to school in late March as a local celebrity, teased by her peers as "Miss H5."

A vital question
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 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 instance. 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. "When I returned to my home town, I felt as if I were born again."