The World Health Organization (WHO) has sent three specialists to Nigeria to support local efforts to identify the source of the country’s first human case of avian influenza.

The specialists will remain in Nigeria for up to two weeks, assisting in laboratory analysis and the detection of potential sources of avian flu in the environment, said Dick Thompson, a spokesman for WHO in Geneva.

“During an outbreak of a new disease very often certain specialties are overwhelmed or they don’t have the familiarity at hand so we send experts to support the work that is going on, but more importantly train people in a new skill,” Thompson told IRIN on Monday. “This investigation would be... to detect the source of infection of this single human case.”

The WHO Collaborating Centre for Reference and Research on Influenza in London has confirmed laboratory tests conducted in Nigeria that showed a 22-year-old woman in Nigeria’s main economic city Lagos died of the H5N1 strain of avian flu on 17 January.

The H5N1 avian influenza virus has killed millions of birds and poultry around the world as well as more than 160 humans, mostly in Asia.

Scientists fear the virus could mutate into one that is easily transmissible from human-to-human and trigger a global pandemic that could kill several million people. Health experts are therefore working to contain any outbreaks of the illness in birds or humans. Tens of thousands of birds were culled in the United Kingdom this week after an infected bird was found there.

Thompson said so far there was no indication how the Nigerian woman died. Nigerian officials said she had slaughtered chicken to prepare a family meal before her death. Her 52-year-old mother had also died of similar symptoms on 4 January, officials said.

Nigerian Information Minister Frank Nweke Jr. said on Monday that tissue samples have now been taken from the mother’s body for testing. He also said the Nigerian government was working with WHO to conduct additional laboratory investigations to determine the possible extent of human exposure to the virus.

Nweke said the key challenge now facing public health authorities was to find out if there are other infected persons anywhere in the country and take measures to prevent further spread.

"It bears restating, therefore, that H5N1 is widespread and continuing in the poultry population in Nigeria," Nweke said.

Bird flu has appeared in 19 of Nigeria’s 36 states since the first cases of the H5N1 virus were reported in the country a year ago.

Nigeria, Africa’s most populous country with some 140 million people, is of particular concern to international health experts because of its poor infrastructure. Additionally, Nigerians have criticised compensation schemes for people who have had to cull their infected poultry as being inadequate, triggering fears that sick fowl will continue to be sold and eaten.

But Thompson said Nigeria responded quickly and appropriately after its first human case of avian flu was suspected.

“I think what’s important to see in Nigeria is that this case was picked up, that the person was isolated and it’s being invested and samples were sent out of the country for confirmation, and all of those are critical steps in a new avian influenza outbreak,” he said.

After the first human case was reported in Nigeria, health officials said they were strengthening surveillance efforts across the country with particular emphasis on monitoring human contacts with poultry to prevent further infection.

WHO advised that people should only consume chicken that has been properly cooked “until none of the meat is red”, stressing there is no evidence of infection from poultry or eggs that have been thoroughly cooked.

"The greatest risk of exposure to the virus is through the handling and slaughter of live infected poultry,” Nweke said. “Therefore, good hygiene practices are essential during slaughter and post-slaughter handling to prevent exposure through raw poultry meat or cross contamination from poultry to other foods, and from food preparation surfaces or equipment."