A strain of bird flu that infected a Vietnamese girl in February has developed resistance to the main antiviral drug being stockpiled in the event of an influenza pandemic. The finding raises concerns that the drug alone may not be sufficient to fight a bird flu outbreak in humans, write Dick Ahlstrom, Science Editor, and Jamie Smyth, European Correspondent.
The Government has ordered a million doses of the drug, Tamiflu, but it was ineffective against the bird flu strain found in the girl and her family, according to a study of the case, published yesterday by the journal Nature. It suggests that the use of the drug itself may have caused the virus to become resistant.
The study was published as EU veterinary experts agreed a package of emergency measures last night designed to prevent the spread of the virus.
The measures focus on reducing contact between wild birds and poultry and introducing an early detection system in high-risk areas.
The Vietnamese girl appears to have caught the infection from her brother rather than from birds. There have been almost no documented cases of human-to-human infection caused by the H5N1 bird flu virus. Both survived their illness.
The family received Tamiflu but may have taken doses that were too small, encouraging resistant virus strains. While the virus survived treatment with Tamiflu (oseltamivir), it was killed off by another antiviral drug, Relenza (zanamivir).
It may be necessary to stockpile more than one antiviral drug in the event of a H5N1 influenza pandemic, the authors suggest. They also suggested close monitoring for the emergence of resistant strains.