The spread of bird flu from Asia
to eastern Europe
and now west Africa
has increased the chance the virus will mutate and set off a pandemic, the U.N. bird flu chief said.
Dr. David Nabarro said there is no evidence yet of any change in the virus, which has killed at least 88 people since 2003.
Almost all the deaths have been linked to contact with infected poultry, but experts fear the virus could mutate into a form that spreads easily among humans, setting off a pandemic.
"Unfortunately, we cannot tell when the mutation might happen, or where it might happen, or how unpleasant the mutant virus will turn out to be," he said in an interview. "Nevertheless, we must remain on high alert for the possibility of sustained human-to-human virus transmission
and of a pandemic starting at any time."
Nabarro said the arrival of bird flu in Nigeria should be "a strong wake-up call" to all countries to ensure that their veterinary services are on alert and report any instances of birds or poultry dying, and that health
services quickly identify unexpected clusters of unexpected disease that could represent the start of a pandemic.
"We have got bird flu now in southeast Asia
, central Asia, eastern Europe
, and west Africa
," he said. "Compared with eight months ago, this is a major extension of the avian influenza epidemic."
Nabarro said control measures put in place by countries have helped to contain the spread but bird flu is still expanding across the world "putting at risk the health
of people who are living intimately with poultry and also adding to the overall load of the H5N1 virus."
He said it is the increase in the quantity of the virus in the world today that has boosted the overall chance of mutations, including a mutation that could cause a disease which could then spread through the human population.
"That's why we get so concerned about the spread of the virus, because we want to do everything we can to reduce the opportunity for mutation," Nabarro said.
He said one of the urgent needs is to establish how avian influenza reached west Africa.
"The likely means is by migrating wild birds traveling from north to south, and one of the main migratory routes passes from Siberia through the Black Sea area, including Crimea and on to west Africa," Nabarro said. "The alternative is that the virus arrived in birds that are being traded - and if that is the case they would have been smuggled as Nigeria had banned import
of birds from avian influenza affected areas during the last two years."
U.N. experts have just received the genetic sequence of virus samples taken from the farm in Kaduna where the H5N1 strain of bird flu was discovered, he said.
Over the next few days, he said, the World Organization for Animal Health and the U.N. Food
and Agriculture Organization will try to match that sequence with the genetic sequence of viruses from birds in other countries affected by bird flu, he said.
"If it turns out that H5N1 was carried to west Africa by migratory birds, we need to be prepared for the possibility that within the next six months it could be brought back to the northern hemisphere - but perhaps along a different flyway," Nabarro said.
"And that could mean that countries in Western Europe and North American should be bracing themselves for the possible introduction
of H5N1 avian influenza," he said.
Nabarro said the challenge facing governments throughout Africa "will be to pick up instances early of suspected bird flu, quarantine the affected farms and communities so that the birds are not moved in or out, and then to stamp out the infection through selective culling."
most important thing governments can do, he said, is to put a total ban on bird movements in any area where bird flu is suspected.
With several outbreaks of bird flu now confirmed in Nigeria, Nabarro said, there is a need for special vigilance in other countries on the west African coast including Togo, Ghana, Liberia and Sierra Leone.
Nabarro said he was delighted that the Nigerian government
will pay compensation for birds killed, "but unfortunately that never truly replaces the lost
"The sadness is that this will directly affect poor people for whom a chicken is a short-term savings account with an excellent rate of interest, and they depend on their birds for getting cash at times of need," he said.
Nabarro also praised the action being taken by Nigeria's Ministry of Agriculture, "which appears to be firm and rapid," but he expressed concern that the scale of the problem could overwhelm authorities.
"For that reason, rapid international assistance to Nigeria and support to neighboring countries is critical and the decision by WHO and FAO to provide urgent extensive support is the right one," Nabarro said.