March 14, 2006

China urged to test healthy chickens for H5N1

Experts are urging China to conduct random tests on live poultry in its retail markets after a study found that some apparently healthy chickens, ducks and geese were infected with the deadly H5N1 virus.

The calls follow the death of a man from H5N1 this month, who fell sick after visiting poultry markets in southern Guangdong province.

Ten people in China have died from H5N1 so far, but most of the cases occurred in places where there were no reported H5N1 outbreaks, leading to speculations that infected poultry with no symptoms may be the culprits.

That theory gained traction after scientists found that up to 1 percent of apparently healthy poultry in wet markets in southern China were in fact carrying the virus.

The finding is significant because people can no longer rely on signs of disease to tell if their flocks are infected and people working around chickens may not even be aware if they themselves are infected.

However, Julian Tang, a microbiologist from the Chinese University in Hong Kong, noted that since nearly all the human cases so far were linked to chickens with symptoms, there seems to be a lesser chance that healthy infected chickens with no symptoms could pass the virus to humans.

The appearance of such chickens in China has raised questions about China-made vaccines.

Experts say that the mass vaccination policy resulted in chickens that look well but are in fact infected, said a source familiar with the situation, adding that since the vaccines used are not dedicated to H5N1, they are only designed to keep the virus at bay, not kill it.