Japan finds case of H1N1 resistant to Tamiflu

Japan has confirmed its first case of a genetic mutation of the new H1N1 influenza that shows resistance to Tamiflu, the main antiviral flu drug, a health ministry official said today.

The World Health Organisation has declared a global pandemic is under way from the virus, known as swine flu, which has so far been treatable with Tamiflu, made by Switzerland's Roche.

Takeshi Enami, an official at Japan's health ministry, said that the patient's sensitivity to Tamiflu had yet to be tested.

The patient, who was confirmed in May with the H1N1 strain of the flu in the Osaka prefecture of western Japan, has since recovered and no other cases of the new flu have been confirmed around the patient, Enami said.

He could not confirm the age or the sex of the patient.

The first case of H1N1 that did not respond to Tamiflu was a patient in Denmark.

Earlier this week the WHO said that case, revealed by Roche and Danish officials on Monday, was an isolated one and did not amplify the severity of the virus.

Resistance to Tamiflu has been previously documented in the deadly bird flu virus H5N1 and seasonal H1N1 flu.