THE H5N1 bird flu virus may be evolving the ability to spread from mammal to mammal, the crucial change that could lead to a pandemic, according to a team that has tracked infected pigs in Indonesia since 2005.
The H5N1 strain kills 60 per cent of infected people. However, most infections occur after direct contact with an infected bird and as long as human transmission remains rare, the virus cannot cause a pandemic.
Chairul Nidom of Airlangga University in Surabaya, Indonesia, and colleagues, have been tracking H5N1 in pigs in Indonesia, the country hardest hit by the avian flu virus. , 7.4 per cent of 700 pigs they tested carried H5N1. There have been sporadic reports of H5N1 in pigs but this is the first time the extent of the problem has been measured.
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In each case, the virus in pigs closely resembled H5N1 from nearby outbreaks in poultry, suggesting it had jumped from birds to pigs. That, and the small proportion of pigs infected, suggests the virus cannot yet spread readily from pig to pig.
But Nidom says that in one pig, the virus had developed the ability to bind to a molecule present in the noses of both pigs and humans 鈥� exactly the kind of change that could allow it to spread easily between people (Emerging Infectious Diseases, ).
鈥淭his shows why we should keep a close watch on pig flu,鈥� says Ab Osterhaus at the University of Rotterdam in the Netherlands.