Analyses of H5N1 Southeast Asian bird flu samples shows the two strains causing human disease are related and belong to two distinct genetic subgroups.
"As the virus continues its geographic expansion, it is also undergoing genetic diversity expansion," said Rebecca Garten, a researcher on the study. "Back in 2003 we only had one genetically distinct population of H5N1 with the potential to cause a human pandemic. Now we have two."
What that means, says Garten, is that the pool of H5N1 candidates with the potential to cause a human influenza pandemic is getting more genetically diverse, which makes studying the virus more complex and heightens the need for increased surveillance. She expects further continued diversity in the future.
"Change is the only constant," said Garten. "Only time will tell whether the virus evolves or mutates in such a way that it can be transmitted from human to human efficiently."
The findings by the U.S. Centers for Disease Control and Prevention were reported Monday in Atlanta, Ga., during the International Conference on Emerging Infectious Diseases. |