New H7N9 bird flu resists drugs without losing ability to spread

Scientists have found that a mutation in a new strain of bird flu infecting people in China can render it resistant to a key first-line treatment drug without limiting its ability to spread in mammals.

The discovery means that unlike seasonal flu strains, which often become less transmissible when they develop resistance to drugs like Roche's Tamiflu, the new H7N9 bird flu does not lose any of its spreading potential with drug resistance.

While this does not make H7N9 any more likely to develop into a human pandemic, researchers said it means doctors should be prudent in their use of anti-viral medicines to treat H7N9 cases, and consider using drugs other than Tamiflu, such as GlaxoSmithKline's Relenza, where possible.

"It's important to emphasize that these H7N9 viruses seem to transmit fairly inefficiently overall," said Nicole Bouvier, who led the H7N9 study which was published in the journal Nature Communications on Tuesday.

"But what was surprising about our study was that the drug-resistant virus was no less efficient than the drug-sensitive one. Usually what we see with influenza, is that resistance...also confers a fitness disadvantage on the virus." Read more >>