Researchers say studies do not confirm whether wild birds are carriers of the H5N1 bird flu virus. VOA's Luis Ramirez reports from Bangkok, where experts are gathering this week to figure out better ways to track how the disease is spreading.

Experts meeting in  say they have been dealing with data that might be unreliable because there is no uniform system of checking H5N1 infection among wild birds. The Food and Agriculture Organization brought together more than 70 experts from 12 countries.

Scott Newman, the FAO's international wildlife coordinator, says the aim is to identify what countries need what kind of support and training to improve their surveillance of wild birds.

"We are hearing that wild birds have not been found to be positive if they are healthy, free-ranging birds. We are hearing, though, that dead wild birds are being found in various countries and they are confirmed positive for H5N1 avian influenza," said Newman. "So, from a surveillance standpoint, some countries are doing healthy wild-bird surveillance. Others are just collecting dead birds and looking for disease. And so there is a range of surveillance activities and monitoring that are happening."

Bird flu experts say it could be that there is no significant incidence of bird flu among migrating wild birds, or it could be that the virus is simply not being detected. They say the only way to find out is to establish a comprehensive and uniform system of surveillance.

FAO officials last year voiced concerns that bird migration patterns might have spread disease Asia and Europe to Africa. But as elsewhere in the world, very few cases have been found among wild birds in Africa.

The Wildlife Conservation Society Field Veterinary Program Director William Karesh is among those attending the meeting in Bangkok.

"We tested thousands of birds in Africa, in Nigeria, in that area, and we cannot find a wild bird with the disease. [That] Does not mean it cannot occasionally get into them, but it is probably not going to go anywhere. It is a dead end," he said.

Karesh says the illegal trade in wildlife in Africa and other parts of the world makes it especially challenging to track the virus.

Since an outbreak began in 2003, millions of chickens, ducks, and geese around the world have contracted the virus and millions more were culled to prevent its spread.

The World Health Organization says more than 320 people have been infected with bird flu in 12 countries, and about 200 have died. Indonesia and Vietnam account for almost two thirds of the human cases.