Japan: Flu virus resistant to Tamiflu verified

THE ASAHI SHIMBUN

2009/7/4

A mutated form of the new swine flu virus that is resistant to the drug Tamiflu was confirmed in a woman in Osaka, health officials said Thursday.

It was only the second detection of such a virus in the world, following one in Denmark in late June.

The National Institute of Infectious Diseases will examine the mutated virus in detail.

According to the Ministry of Health, Labor and Welfare and the Osaka prefectural government, the female teacher in her 40s started receiving Tamiflu from May 18 as a preventive measure because she had been in close contact with a person infected with new swine flu.

But she developed a slight fever May 24, and was confirmed infected with what was then believed to be the new swine flu virus on May 29.

She later recovered after receiving the drug Relenza.

The Osaka Prefectural Institute of Public Health conducted genetic examinations of her virus samples and found that the disease was in fact a mutated form of new swine flu that is resistant to Tamiflu.

Officials of the Osaka prefectural institute said the swine flu virus underwent a sudden genetic mutation when she was receiving Tamiflu.

Health officials said there is no reason to panic. They noted that the mutated virus has not been detected in other people who were also in close contact with the same person.

"Mutations are often seen in seasonal H1N1 flu viruses, so we had expected a similar mutation would occur in the new swine flu virus," said Yoshinobu Okuno, director of the Kanonji research institute of the Osaka University's Research Foundation for Microbial Diseases.

"But if Tamiflu is not effective for patients with serious symptoms, it could be a big problem. Medical institutions that treat high risk patients should prepare not only sufficient amounts of Tamiflu but also Relenza," he said.

Nearly 100 percent of seasonal Type A Soviet Union flu viruses have mutated into ones resistant to Tamiflu.

Health officials said the Osaka woman was not infected by any of those viruses.(IHT/Asahi: July 4,2009)