Fears that the deadly strain of bird flu would move through Africa and Europe in flocks of wild birds have so far proven unfounded, but the danger is not entirely over, a Dutch environmental group said Thursday.
Experts from Wetlands International tested some 5,000 wild birds in countries including Tunisia, Egypt, Burkina Faso, Sudan, Senegal, Malawi and Kenya but didn't find the highly pathogenic H5N1 virus, which can be fatal in humans, said Ward Hagemeijer, who studies the disease for the organization.
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Scientists had feared that the spread of the virus would pick up speed with the birds' winter migration to Africa and the Middle East, and their spring return to Europe.
"Theoretically, it is still possible," Hagemeijer said, referring to an outbreak of the disease in Europe. But he said the risks now appear low.
Scientists say they do not know why bird flu does not appear to be spreading in the wild as widely and quickly as feared.
While bird flu experts say are relieved that they have not found the deadly strain in many migrating birds, the data they have gathered is limited and they are not ready to declare victory against H5N1 in wild fowl.
"It's a needle in the haystack, and in the haystacks we looked, we didn't find any needles," said Juan Lubroth, a senior officer for animal health at the U.N. Food and Agriculture Organization in Rome.
Lubroth said the researchers were hampered by a shortfall in funding, and that without wider data collection across the years, "we'll just have a snapshot and that is a shame."
In the Netherlands, which sits on a major bird migration path, more than 13,000 wild birds have been tested since February. None showed signs of H5N1. Earlier this month, the government attributed its success to measures to contain the spread of the virus, and good luck.
"Naturally, there were the measures we took, and maybe that had its effect, but you can also say we were just lucky," said Agriculture Ministry spokeswoman Nynke van der Zee.
The virus appeared in February in swans and other wild birds in widely dispersed areas of Europe, which went on high alert. The European Union ordered free-range domestic poultry to be kept indoors to avoid contact with potentially infected geese and other migrators.
The EU has begun easing some restrictions in recent weeks, but extended preventive measures for poultry in farms near wildlife water reserves and river deltas until the end of the year.
H5N1 has been spreading from Asia to Africa and Europe since 2003. At least 113 people have died from the strain, which led to the slaughter of more than 200 million animals to prevent what health officials had warned could be a lethal pandemic.