The World Health Organization is sending a team of public health experts to Nigeria in the coming days to assist efforts to control avian influenza. WHO calls the detection of bird flu in the vast West African country a cause for great concern that demands immediate action.

Birds for sale on Lagos street

The deadly H5N1 avian flu virus now has been confirmed in three states in northern Nigeria, Kano, Plateau and Kaduna. Large numbers of chickens have died in Kaduna, where the first case of the disease was found.

Michael Perdue is an epidemiologist at WHO's global influenza program. He says a team of seven or eight experts will go to Nigeria to try to prevent human cases of bird flu. So far, he says, there is no evidence that humans have been infected with the disease in Nigeria.

"We are concerned with the fact that this particular strain of H5N1 now has moved through Asia, through Central Asia, Kazakhstan, Russia, Mongolia, Romania, Ukraine, Turkey, Iraq and now down into Africa," said Perdue.

The World Health Organization says it is absolutely crucial to warn people about the dangers of close contact with sick or dead birds infected with the H5N1 virus. It says the vast majority of all human cases and deaths from H5N1 have occurred in previously healthy children and young adults who came in close personal contact with infected birds.

More than 80 people have died of bird flu since December 2003 when the disease re-emerged. Most of these deaths have occurred in Asia. But, recently deaths have been reported in Turkey and Iraq, and officials are concerned the disease could mutate and begin spreading among the human population.

A mass polio campaign to immunize 40 million children in Nigeria against this crippling disease kicks off this weekend. The Coordinator of WHO's Polio Initiative, Bruce Aylward, says the campaign also will be used to inform people about the dangers of bird flu. At the same time children are being vaccinated, he says people will be told that no one must touch infected birds.

"If there is any silver lining in what has happened in Nigeria is that we are detecting disease, avian flu in the place where we have one of the strongest surveillance and operations infrastructures in Africa," said Aylward. "As many of you know, as people have watched the movement of avian flu, there has been great concern about what happens when this gets into areas with weak infrastructure - sub-Saharan Africa, South Asia. But, in fact, we have a much stronger infrastructure of surveillance there than many of the countries that have already been infected by the disease."

The World Health Organization plans mass polio immunization campaigns in early March in neighboring Chad, Cameroon, Benin and Niger. Aylward says a similar bird flu information campaign may take place there as well. He says the critical thing is to prevent human exposure to the virus from happening.

Scientists warn of a potential bird flu pandemic that could kill millions of people if the H5N1 virus mutates.