David Nabarro, the UN co-ordinator for avian and human flu, said that migrating birds carried the virus last season, probably from Mongolia
and South Korea
But he told a news conference at the United Nations on Friday: "We suspect that one of the reasons for the current spread has more to do with trade in live birds than to do with the movement of the virus through wild birds."
In November, South Korea confirmed its first case of the H5N1 strain in almost three years.
Pakistan suffers third case
A third case of the H5N1 strain of bird flu has been confirmed in Pakistan, health authorities said on Saturday.
|Four children are under observation in hospital |
after a bird flu outbreak in Turkey [AFP]
Two cases of the deadly virus were found in small flocks of chickens and peacocks in the town of Rawalpindi, close to the captal Islamabad, and in the northwest town of Mansehra.
About 40,000 birds were culled after the first cases of H5N1 in Pakistan were reported in February last year in North West Frontier Province.
There have been no cases of people being infected with the virus in Pakistan.
A fourth child with flu-like symptoms has been taken to hospital after chickens died of the deadly H5N1 strain of bird flu in a village in southeastern Turkey, local officials said on Friday.
Turkey confirmed an outbreak of bird flu in the impoverished Batman province on Thursday, a year after the H5N1 strain of the disease killed four children in the region.
The virus has killed 166 people in 11 countries and scientists fear it could mutate into a strain that spreads easily among people, triggering a global pandemic.
"We expect that there will be more and more outbreaks," especially during the northern winter season, from November to June, Nabarro said.
Since late last year, outbreaks of avian flu have swept from Asia to Britain, as well as reaching Egypt and Nigeria.