A researcher at the University of Wisconsin-Madison has identified two mutations in the avian flu virus, H5N1, that may allow the virus to transfer from birds to humans.,”

Even though major media coverage of the bird, or avian, flu virus has slowed down, it is still a pressing issue for the nation's health.

Researcher Yoshihiro Kawaoka at the University of Wisconsin-Madison has identified two mutations in the avian flu virus, H5N1, that may allow the virus to transfer from birds to humans.

Originally discovered in 1997, the virus has changed significantly from when it was first identified.

"There are big differences between the virus first found in 1997 and the virus we see now. We are watching the virus turn itself into a human pathogen," said Kawaoka, a virologist in UW-Madison's School of Veterinary Medicine, in a press release.

According to the press release, Kawaoka has conducted research by comparing strains of the virus found in infected birds to strains contracted by humans.

"(Both) changes are important. (They) are needed for the H5N1 virus to recognize human receptors," Kawaoka said.

The avian flu virus is species specific, usually infecting only birds and some pigs. However, mutations Kawaoka found in the virus have identified the way it crosses from species to species, in particular from birds to humans.

Large outbreaks of the virus in southeast Asia have led to the killing of 150 million birds in that region in attempts to eliminate the virus, said Dan Epstein, information officer for the Pan American Health Organization, an extension of the World Health Organization.

"Bird flu is different from seasonal flu because it is a very aggressive disease and can lead to viral pneumonia or multiple organ failure," Epstein said.

When most of the bird flu outbreaks were publicized earlier this year, there were a total of 258 reported human cases, 153 of which resulted in death.

"That's what scared people so much – almost half of the people with this disease died. But almost all of the people who died had very close contact with infected chickens," Epstein said.

Epstein said there were no reports of cases that transferred from human to human.

For a virus to spread, it has to be able to recognize and attach to cells from its chosen host. Since avian flu is species-specific, it does not naturally recognize human cells. Kawaoka's research found that the virus can evolve easily to adapt to humans.

"If the virus is given the opportunity, it could mutate into being contagious for humans and could lead to a global pandemic," Epstein said.

Though the number of reported cases has slowed down significantly, there is still cause for concern.

"Most of our previous pandemics have come directly from birds," said Steve Baragona, spokesman for the Infectious Disease Society of America. "The threat is definitely still there and the mutations show that."

Despite continuous concern, Kawaoka's research is still reassuring.

"It's helpful to know," Baragona said. "We at least know that it's made these mutations and hasn't caused a pandemic yet, but it's more of a warning."

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