Some Countries May Have Slowed Bird Flu's Spread

(HealthDay News) -- Several strains of H5N1 bird flu virus that afflicted southern China were blocked from entering neighboring Thailand and Vietnam, say University of California, Irvine, researchers who conducted the first-ever statistical analysis of H5N1's genetic diversity.

The information gleaned from this analysis may help scientists better understand how the strain migrates and, in future, determine the success of programs to halt the spread of the virus. The study was published online Feb. 27 in the journal PLoS One.

"Some countries appear more exposed to bird flu invasion than others. Learning that is a good step in discovering which social and ecological factors promote, or, on the other hand, hamper the virus' spread," lead author Robert G. Wallace, a postdoctoral researcher, said in a prepared statement.

He and colleague Walter M. Fitch, professor of ecology and evolutionary biology, analyzed almost 500 publicly available genetic sequences of proteins found on the surface of H5N1 samples collected from 28 locations in Africa, Asia and Europe.

They found that H5N1 strains in Indonesia, Japan, Thailand and Vietnam shared the most evolutionary history with H5N1 found in three southern Chinese provinces -- Guangdong, Fujian and Hong Kong -- that are engaged in intensive international trade, including poultry.

Previous research has identified poultry trade as the key factor in the spread of H5N1.
The type of genetic analysis used in this study could help health officials in different countries determine whether their efforts to control H5N1 are effective, the UCI researchers said.

"You can think of it as a type of evolutionary forensics," Wallace said. "When a bomb explodes, investigators can determine how many charges went off and the strength and direction of the blast, all from the resulting damage alone. Here we can determine the way H5N1 has spread and evolved by the resulting viral diversity."

More information
The World Health Organization has more about bird flu.