Sample from Turkish patient shows mutated Bird Flu virus

January 23, 2006

A mutated form of the Avian (Bird Flu) virus has been found in a sample taken from a Turkish patient.

The mutated form is said to make the virus easier to attach itself to humans rather than animals says a report in the Nature journal.

The situation is being monitored by the World Health Organization but says "it is too early to know whether the virus is changing in ways that would signal the start of a human flu pandemic," says Maria Cheng a spokeswoman for the WHO. "It's one isolate from a single virus from Turkey. The sample suggests the virus might be more inclined to bind to human cells rather than animal cells, but there's no evidence that it's becoming more infectious. If we started to see a lot more samples from Turkey with this mutation and saw the virus changing, we'd be more concerned."

However, the Nature report says there is a second mutation that also "signals adaptation to humans." Cheng also said that "flu viruses mutate all the time. For us to assign public health significance to a genetic change we need to match it to what is happening epidemiologically — how the virus is behaving — and clinically — if it's more or less virulent."

In Turkey the fatality rate from the Bird Flu is 50% where elsewhere in the world reports of infection were only scattered. Entire families have been affected in Turkey and more reports come out almost every day of mild symptoms.

So far, Turkey has suffered four deaths and 21 infections. In addition to those cases the WHO reports 145 cases and 80 deaths in Cambodia, China, Indonesia, Thailand and Vietnam.

"When this outbreak (in Turkey) was first reported, there was a lot of concern it was behaving differently," said Cheng. Subsequent investigation, however, has indicated no major behavioral change.

"The team there told us that after two weeks of investigating, they haven't found substantial differences in the pattern we've seen in Southeast Asia," said Cheng.

The mutations were discovered by scientists in London, England in a lab.

Cheng said this may "signify the virus is trying different things to see if it can more easily infect humans. So far, we haven't seen that the virus has the ability to do this. But it's important that we continue monitoring. We would be concerned if we were seeing successive generations of spread of the virus. We haven't so far. All these people had a very clear history of contact with diseased birds."

Health officials say that so far they do not see any evidence yet that the virus can spread easily in humans.

The Bird Flu virus, strain H5N1, first started to infect humans in 1997 in Hong Kong. In 2003 it re-emerged and it has so far been difficult to control.