Mutation found in Turkish bird flu

Published on 13/01/2006 00:59

ANALYSIS of samples of the H5N1 bird flu virus from two of its victims in Turkey has detected a change in one gene in one of two samples tested.

But it is too early to tell whether the mutation is important, the World Health Organisation said last night.

The mutation allows the virus to bind to a human cell more easily than to a bird cell.

It is a shift in the direction of the virus towards being able to infect people more easily than it does now. However, that does not mean the mutation has taken root.

"We assume this could be one small step in the virus' attempt to adapt to humans," said Mike Perdue, a WHO virologist. "But it's only seen in one isolate and it's difficult to make sweeping conclusions. We just have to wait and see what the rest of the viruses from Turkey look like."

Turkey has seen an unusually high number of cases in a short period of time.

Health authorities there yesterday raised the confirmed number of people infected with H5N1 from 15 to 18 after it turned up in preliminary tests on two people hospitalised in south-eastern Turkey and in a lung of an 11-year-old girl who died last week in the same region.

All the victims are thought to have close contact with infected poultry. Samples from several of those cases are being sent to a specialist laboratory in Britain for analysis.

Mr Perdue said the UN health agency is not alarmed by the finding in a single virus sample because this exact genetic change has been seen before, in samples from Southern China in 2003, and it had no impact on the course of the disease, the behaviour of the virus or the pattern of human infections.

"If we saw it in more than 50 per cent of samples, it would suggest the virus is really trying to adapt to humans and it would be problematic," Mr Perdue said.

Even if the mutation is confirmed in more samples, that does not necessarily mean it is an important enough change on its own to make the virus easily transmissible between humans.

The 1918 flu pandemic became a global killer only after the virus slowly made a series of mutations. Flu viruses are notoriously volatile and experts expect to see frequent mutations.