New reports about a Beijing woman who died of avian influenza may raise fresh fears about a possible resurgence of the disease, which peaked in 2006.
And new research cautions the U.S. against relying on antiviral drugs such as Tamiflu to protect people against infection.
Scientists at Ohio State University say that evidence shows bird flu became resistant to antiviral agents known as adamantanes, which were used in Asia and Russia.
By 2006, these drugs were considered worthless because 90 percent of strains were resistant.
The researchers then analyzed 700 avian flu genomes isolated from a variety of hosts, discovering that one-third had mutations that allowed these strains to resist adamantane drugs.
"We can’t necessarily say what we’ve seen in adamantanes is predictive of what will happen with Tamiflu, but in the larger dynamic, perhaps it serves as a cautionary tale," commented senior author Daniel Janies.
In 2007, the World Health Organization warned that a strain of avian flu resistant to Tamiflu had been discovered in Egypt.