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Bird Flu Vaccine May Increase Virus Peril

Posted on: Saturday, 15 October 2005, 09:00 CDT

By JOHN VON RADOWITZ Daily Post Correspondent

ATTEMPTS to control the deadly bird flu that threatens a global pandemic could be helping to create a drug-resistant form of the virus.

Scientists have identified a strain of the H5N1 virus in Vietnam that is resistant to Tamiflu, the drug being stockpiled to fight any outbreak in the UK.

It was found in a Vietnamese girl who had been put on a course of preventative treatment with Tamiflu for four days in February.

The British Government has no plans to offer Tamiflu, one of a class of drugs called neuraminidase inhibitors, to healthy people as a precaution.

But prophylactic (taken as a preventative measure) useof Tamiflu is part of the control measures being adopted in Asian hotspots where about 60 people have been killed by the virus.

The new findings, due to be published in the journal Nature next week, suggest it may be contributing to the emergence of drug resistance.

The girl had received prophylactic course of 75mg of Tamiflu once a day from February 24 to February 27.

After developing symptoms, she was given a therapeutic dose of 75mg twice a day and eventually recovered.

Scientists examined viruses isolated from the girl before she started the therapeutic treatment. They believe she may be one of the first H5N1 victims to acquire the virus through person-to- person transmission.

Up to now, the virus has only been known to pass from birds to humans. At least one other case of transmission between humans has been suspected but not confirmed.

Health experts fear that if the virus mutates into a form that transmits easily between people it could trigger a global pandemic claiming millions of lives.

A team led by Yoshihiro Kawaoka, from the University of Tokyo, in Japan, looked at 10 viral clones from the girl and found six were highly resistant to Tamiflu.

Further tests on ferrets showed Tamiflu was not effective in animals infected with the resistant virus.

However, even the highly resistant virus did succumb to another drug, zanamivir, marketed as Relenza, which has been suggested as an alternative bird flu treatment but so far not been widely adopted.

The researchers write in Nature: "Although our findings are based on a virus from only a single patient, they raise the possibility that it might be useful to stockpile zanamivir as well as oseltamivir (Tamiflu) in the event of an H5N1 influenza pandemic.

"They also highlight the importance of monitoring the emergence of drug resistance in H5N1 isolates from patients treated with neuraminidase inhibitors

Source: Daily Post; Liverpool

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