Human nose may be too cold for avian flu

LONDON, May 15 (UPI) -- The swine flu is a current worry, but bird flu viruses do not cause pandemics in humans easily, British and U.S. researchers said.

The study, published in PLoS Pathogens, found avian influenza viruses do not thrive in humans because the temperature inside a person's nose is too low.

Researchers at Imperial College London and the University of North Carolina said there are 16 subtypes of avian influenza and some can mutate into forms that can infect humans, by swapping proteins on their surface with proteins from human influenza viruses.

The study shows that normal avian influenza viruses do not spread extensively in cells at 32 degrees Celsius, or 89.6 Fahrenheit, the temperature inside the human nose.

The researchers said this is probably because the viruses usually infect the guts of birds, which are warmer, at 40 degrees Celsius, or 104 degrees Fahrenheit.

Wendy Barclay, one of the study authors at Imperial College London said that avian flu viruses that have not mutated are less likely to infect people, because the first site of infection in humans is usually the nose.