Flight patterns of some migratory birds match the spread of the bird flu that has hit many Asian countries, experts say.

That may explain the fast spread of the disease across Asia.

"People have to be careful not to touch wild birds directly while watching them in the forthcoming migratory season," said a Beijing-based expert yesterday.

He included land birds, shore birds, gooses, ducks and birds of prey in the list of possible disease carriers, although there is no direct evidence to back the claim that migratory birds are in fact spreading the H5N1 strand of avian influenza.

However, their quick flights could rapidly carry the virus from one area to another, said Shi Guangfeng, a doctor with a hospital attached to Shanghai-based Fudan University, in an interview with the Shanghai Evening Post yesterday.

Shi said migratory birds are probably only a carrier of the disease.

He said migratory birds may pass through infected poultry farms and their toes and feathers may come in contact with infected feces. The virus may be able to live for more than 10 hours or up to several days in the feces of infected poultry.

Cui Zhixing, a researcher from Shanghai Natural Museum said, "we can not rule out the possibility regarding the route of migratory birds."

The fly paths of the area's migratory birds are rather wide, with a diameter up to about 1,000 kilometres across most of the Asia-Pacific area.

Most migratory birds like hooded cranes usually take off from Northeast China or Siberia, pass through the Republic of Korea (ROK) in the Korea Peninsula, then fly over Japan, which matches the patch of the outbreak from ROK to Japan.

From Japan, migratory birds can fly downwards to the middle and lower reaches of the Yangtze River and China's coastal areas including Taiwan, he added.

Cu Guozhong, a researcher at the Beijing-based National Bird Banding Centre, said that massive flights of migratory birds usually moves from north to south in autumn and from south to north in spring following changes of temperature.

(China Daily February 2, 2004)