Bird Flu Mutation Of Concern, Experts Say
Thursday, January 12, 2006
ISTANBUL, Jan. 11 -- Preliminary tests show that the strain of bird flu virus that has stricken at least 15 people in Turkey has evolved in a way that could make it somewhat more hazardous to human beings, although it still lacks the capacity to be passed easily from person to person, international health officials said Wednesday.
The analysis, based on the sequencing of one of the virus's genes, suggests that at least some of the H5N1 bird flu virus here carries a change in one of its proteins, according to Michael L. Perdue of the World Health Organization. That protein is what lets the virus attach to cells and penetrate them.
"It's a little concerning because the virus is still trying new things in its evolution," said Perdue, who is overseeing the agency's response to the Turkish outbreak from WHO headquarters in Geneva.
Influenza experts are studying the apparent change to determine its significance, Perdue said. A spokesman for Britain's Medical Research Council, which is involved in the research, said it would take a few days to confirm the preliminary findings.
The experts say they believe the genetic change could make it easier for bird flu to pass from chickens to people. If the virus were to eventually gain the capacity to be passed easily from person to person, it could trigger a global epidemic.
Nancy J. Cox, who heads the influenza branch at the Centers for Disease Control and Prevention in Atlanta, said the change was found in one sample of H5N1 isolated from a Turkish child who recently died of the infection. The hemagglutinin protein, which the virus uses to attach to cells of the respiratory tract, had an alteration not usually seen in avian influenza viruses. Other incremental changes in the virus have been seen in China and Vietnam since outbreaks began in 2003.
Experts from the U.N. Food and Agriculture Organization warned that the virus could become permanently entrenched in Turkey, thereby increasing its risk to people and the chance it could evolve further. "The highly pathogenic avian influenza virus H5N1 could become endemic in Turkey," the organization said in a statement.
Two deaths have been attributed to bird flu in Turkey. The fatalities were the first outside China and Southeast Asia, areas where a total of 78 people have died in the past two years. More than 100 people have been hospitalized in Turkey with flu symptoms. The patients are under observation as they await test results to reveal whether they suffer from bird flu.
The virus has spread across 30 of Turkey's 81 provinces, from the far east to the Mediterranean coast, and has sparked a frantic effort to stem the disease by killing infected poultry. Even in cosmopolitan Istanbul, bird catchers for the Agriculture Ministry are rounding up fowl raised in the outskirts of the city, gassing them to death and burying them in mass graves.
Perdue noted that the Spanish influenza of 1918, which caused an estimated 40 million deaths worldwide, began as an ordinary bird virus but gradually evolved into a global human killer through a series of these incremental changes.
At a news conference in Ankara, the Turkish capital, international health officials played down fears of a pandemic.
"There is no transmission from human to human so far with a mutation of the virus," said Marc Danzon, WHO's regional director for Europe. "We are not there at the moment, but it is the responsibility for the WHO to look at this. . . . There is no reason to panic."
Bernard Vallat, director of the World Organization for Animal Health, said that the virus was probably introduced in Turkey in October. Vallat said that besides weeding out poultry in infected areas, fowl might have to be vaccinated. "The idea is that you create a protective area around an outbreak through vaccination. This could involve an entire province," he said.
Turkish health workers have killed more than 300,000 domestic birds in roundups across the country since late December. In one district of Istanbul, municipal sanitation officials went door to door in a rural hillside suburb asking residents if they raised chickens and ducks. They chased strays up and down the slippery, muddy hills and ravines, and when they caught one, they stuffed it into a plastic bag. Signs around the neighborhood read, "This District Has Chicken Plague."
Workers dressed in protective gear threw the bags into green containers that looked like large garbage cans. A sanitation worker attached a blue tube from a tank of carbon dioxide to the airtight container, opened the valve and killed the birds. "We prefer to say we are putting them to sleep," said Hikmet Karacay, an Agriculture Ministry official.
Residents, most of whom raised chickens as a sideline to collect the eggs, cooperated. "The real problem is the children," said Gilsen Kaya, who has two daughters. "They like the chickens. They are like pets. That's why it's better to do it at night, when they don't witness the whole thing."
Sipress reported from Jakarta, Indonesia. Staff writer David Brown in Washington contributed to this report.