"We do expect to see some (more) cases because it takes time before the virus in birds has completely disappeared," Dr. Guenael Rodier, who heads the WHO mission to Turkey and is an expert in communicable diseases, told Reuters in an interview.

"We know that the risk remains with close interaction between people and birds but we believe it is going down daily."

Human victims had been confined to East Asia until this month, when three infected children from the same family died in eastern Turkey, showing the deadly H5N1 strain had reached the crossroads of Europe, Asia and the Middle East.

Rodier said the four dead children from the village Dogubayazit caught the deadly virus from contact to sick poultry in late Dec to early Jan. before authorities began a mass culling campaign and the public became aware of the dangers.

The brother of Fatma Ozcan, who died on Sunday at a Van hospital from H5N1, was also diagnosed to have caught the bird flu virus and was in serious condition at a hospital in Van.

"The two siblings were very likely infected on Jan. 1 when culling hadn't yet started and public awareness was not yet there," he said.

Ducks began dying in the family's household flock on Jan. 1, and on that day, the girl, assisted by her brother, slaughtered a duck for food, the WHO said.

Since then people have quickly gone to hospital and received antiviral Tamiflu treatment, which have sharply reduced the risks to their lives, Rodier said.

The virus is already endemic across parts of Asia and scientists fear the H5N1 strain could mutate from a disease that affects mostly birds into one that can pass easily between people, leading to a human pandemic.

The WHO said it would gradually shift its focus in Turkey to studying the bird flu virus rather than emergency assistance.

"Now is the right time to look beyond outbreak control to look at medium- and long-term efforts, particularly on the animal side, and also keep a constant surveillance in Turkey and neighbouring countries," he said.

Bird flu has been found in wild birds and poultry over a third of Turkey's territory, hitting villages from Istanbul at Europe's gates to Van near the Iranian and Iraqi borders.

But Rodier said there was no indication the virus was beginning to pass from humans to humans.

The UN's Food and Agriculture Organization has expressed fears that the virus could take hold in neighbouring countries such as Georgia, Iran, Syria and Armenia.