'Avian Flu Spread by Poultry, Not Wild Birds'

BANGKOK, Sep 3 (IPS Asia-Pacific) - The search for answers to the spread of the bird flu virus is calling into question a long-held practice in science where recognition is given to positive test results, say experts meeting in the Thai capital.

It stems from lack of clear evidence to link wild birds to the cases of avian influenza that have infected poultry populations across countries and continents, they add. Yet this view has not taken flight because of ''a bias in science'' against ''negative test results''.

''Science by its nature is about discovery, about finding something positive and concrete. But there is a problem with science when studies offer a negative result that reveals so much,'' says William Karesh, head of the Global Avian Influenza Network for Surveillance (GAINS). ''There is no provision in science to prove that a negative outcome may be correct.''

And when faced with repeated negative results on tests, scientists ''don't publish that information in a journal,'' Karesh explained to IPS, adding that there is only a provision in science for publishing the outcome of ''positive results'' or ''new discoveries'' from tests.

''It is an interesting paradigm that we are faced with,'' adds Scott Newman, international wildlife coordinator for avian flu at the Food and Agriculture Organisation (FAO), in an interview. ''Positive results from a test are important to understand the ecology of the disease. But in this case, negative results are contributing as much in providing an understanding of this disease.''

This is a picture that is proving too hard to ignore, the experts admitted on the first day of a three-day conference aiming to share information about the role of wild birds in the spread of the deadly H5N1 strain of the virus in poultry. Representatives from 12 countries in the Asian region, the continent worst hit by bird flu, are attending a mix of scientific and non-scientific sessions.

''The reports of negative findings from the countries participating has been fascinating,'' says Karesh, who is also the director of the field veterinary programme for the Wildlife Conservation Society, a nature lobby based in New York. ''But little of that will be published in scientific journals.''

Nor, adds the U.N. food agency, would the results of the tests carried out in wild birds for the H5N1 virus. ''Over 350,000 samples from healthy wild birds sampled in Europe, Asia, Africa and the Americas during 2005-2007 have been negative for (the) H5N1 virus,'' a FAO background note revealed. ''Only a few studies have reported healthy wild birds to be positive for the virus (sparrows, one grebe and a few ducks) in one location.''

''We have done lot in the last three years globally through wildlife surveillance,'' Newman said at a press conference. ''But we have not found a wild bird reservoir for this disease.''

What is more, there is increasing evidence to suggest that ''wild birds are actually the victims,'' he added, referring to cases where migrant birds have got infected from the spill-over from poultry farms. ''The virus can enter the wild birds this way, a case of poultry infecting the wild birds.''

Free ranging birds that have died from the H5N1 virus are divided into three categories, states the FAO. They are migratory water bird species; bridge species, ''which may be non-migratory'' but can ''play a role in transporting (the) disease from poultry to wildlife:'' and predatory birds that ''most likely acquired (the) disease from depredating or scavenging sick or dead birds.''

The experts hope that such a reality will challenge the view that has gained ground since the current outbreak of avian flu began in South-east Asia in the winter of 2003 that wild birds, such as migrant water fowl, are to blame for AI's spread in poultry populations. Governments in the region have gone on record to target wild birds whenever there is a new outbreak of bird flu, often causing concern to nature and wildlife enthusiasts.

''We should not be targeting wild birds, killing wild birds to stop avian influenza,'' says Newman. ''FAO believes that the management of this disease has to be concentrated at the level of agriculture and poultry.''

This strengthens the argument of the FAO that the spread of avian influenza can be traced to the movement of poultry and poultry products in an open and unregulated manner, both within a country and across international boundaries. Poor bio-security measures in poultry farms across Asia have also been identified as another route for the virus spreading.

Since the current outbreak, some 150 million ducks and poultry have been culled in Asia in response to the virus, states the FAO. Its impact on people has resulted in 320 cases reported in 12 countries, of which 193 people have died. The worst affected has been Indonesia.

The strain of the virus in poultry in the region remains largely the same as the one detected when avian flu swept through Asian countries in 2003. (END/IPSAP)