Bird flu might be less deadly than feared

GLOBAL - H5N1 bird flu may be less deadly to people than feared, suggests a study in Vietnam, although the results will require more work to confirm.

This might be good news if H5N1 ever starts spreading more readily among humans. But it is bad news if it means there are far more human infections with the virus, as it means more opportunities for the virus to adapt to humans.

To date, about half the people confirmed to have H5N1 have died – a terrifying fatality rate. By comparison the 1918 pandemic flu virus killed just 3% it made ill. But it is possible that many mild or symptom-free H5N1 infections have gone undetected, meaning the real fatality rate is lower.

One way of uncovering unreported H5N1 infections is to look for antibodies to the virus. Tests on nurses and doctors who have tended H5N1 patients have generally failed to turn up such antibodies.

But what scientists do not know is whether people can catch it from sick poultry – as nearly all the severe cases so far have – and not fall seriously ill.

The grandfather of people who fell ill with H5N1 in Vietnam in 2005 had antibodies but showed no known symptoms, as have a handful of Japanese and Hong Kong workers culling infected chickens. But this might have been after exposure to dead virus, and not from live virus infection.

Source: New Scientist

11 January 2006