I'm Gwen Outen with the VOA Special English Agriculture Report.

Avian influenza could force changes in the way farm birds are raised in Asia. The disease has already hurt the industry. The F.A.O., the Food and Agriculture Organization, says about 140 million farm birds have died or been destroyed.

Oxford Economic Forecasting estimates poultry farm losses in Asia last year at more than 10,000 million dollars.

Top animal health officials from 28 nations met for three days late last month in Ho Chi Minh City, Vietnam. The officials agreed on the need for changes in traditional ways of poultry farming in many Asian cultures.

For example, they said mixing different kinds of birds on farms can speed up the spread of the disease. They also agreed that chickens, ducks and other farm animals such as pigs should be kept separate. And they said human contact with animals should be limited.

A lack of supervision by animal doctors was another problem noted.

The F.A.O. says more than 100 million dollars would be urgently needed to improve animal health services and laboratories. It says several hundred million dollars would be needed for farmers who have lost animals to disease control efforts.

Samuel Jutzi is director of the Animal Production and Health Division of the F.A.O, a United Nations agency. He says wild birds, especially ducks, often carry the virus yet show no signs of sickness. But Mister Jutzi says wild birds should not be destroyed in an effort to protect farm birds.

Evidence suggests that other problems aid the spread of bird flu much more. Mister Jutzi says these include trade in live farm birds and mixing different kinds of live birds at markets. Poor farming methods also help the spread of the disease.

The group that met in Vietnam said vaccines can be an important tool to fight bird flu. The officials said the possibility of vaccinating ducks should be considered.

Experts have mixed opinions about using these preventive medicines on birds. Some are concerned that protecting against one virus may lead to other, more aggressive viruses.

On March 11th the World Health Organization reported 69 confirmed human cases of avian flu since January of last year. These cases in Vietnam, Thailand and, in one case, Cambodia resulted in 46 deaths. Health officials worry that the virus could gain the ability to spread easily among people.

This VOA Special English Agriculture Report was written by Mario Ritter. I'm Gwen Outen.