Bird flu mutation a concern, experts say

ISTANBUL, Turkey – Preliminary tests show that the strain of bird flu virus that has hit 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 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 believe the genetic change could make it easier for the virus to pass from chickens to people. It has not given it the capacity to be easily passed from person to person – a trait the virus would need in order to trigger a global epidemic of bird flu.

Nancy Cox, who heads the influenza branch at the Centers for Disease Control and Prevention, 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.

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.