With bird flu spreading to wild or domestic birds in 17 new countries since the beginning of last month, the United Nations health agency again stressed that humans are not at risk of acquiring the deadly infection through food when poultry products are safely handled and properly cooked.

"The main health risk currently is to people who are in close contact with infected poultry, such as families with backyard flocks and poultry workers in wet markets or live animal markets," the World Health Organization said in a news release.

"Globally, the evidence demonstrates that there is no risk of infection when birds and eggs are well-cooked, as this kills the virus. Poultry products are important sources of protein throughout the world," it added.

Since December 2003 the H5N1 virus, which experts fear could mutate into a potentially devastating and lethal human pandemic, is known to have infected 186 people, of whom 105 have died. Not one of these cases has been linked to the consumption of properly cooked poultry or poultry products, WHO noted.

Heightened surveillance among domestic and wild birds, rapid detection of the virus, and swift implementation of control measures are important in supporting and maintaining consumer confidence in the safety of poultry products, it said.

The great concern is that the virus could mutate into a type that spreads easily from person to person. The so-called Spanish flu pandemic that broke out in 1918 is estimated to have killed from 20 million to 40 million people worldwide by the time it had run its course two years later.

The new outbreaks since February have occurred in Africa, Asia, Europe, and the Middle East.