Marwaan Macan-Markar
BANGKOK, Aug 25 2006 (IPS) – When new strains of the deadly bird flu virus were recently detected in poultry in Thailand and Laos, wildlife enthusiasts had reason to feel vindicated. The prevailing hot weather was off season for migratory birds, often blamed for spreading avian influenza.
By the time ducks in Cambodia showed signs of being infected, the theory that wild birds carry the H5N1 strain of the virus across international boarders was further discredited. This view had first gained hold in this region in 2004 when the current outbreak of the lethal virus began and rapidly spread across a broad sweep of countries.
There has never been any conclusive, properly documented evidence that wild birds are carriers of the virus, Richard Thomas, editor of World Birdwatch, said in an e-mail interview. Tens of thousands of healthy, wild, migrant waterfowl in Hong Kong have been tested over the last decade, yet there is not a single positive-for-H5N1 amongst them.
If the absence of the virus among these waterfowl amongst the highest at risk group of carriers is not enough, the lack of bird flu outbreaks across other parts of Asia that attract wild birds is also helping to protect the reputation of feathered migrants.
Why have there been no outbreaks in countries such as the Philippines, Australia and New Zealand, all major destinations for Asian wild, migrant birds? asks Thomas, whose journal is published by BirdLife International, a global conservation organisation based in Cambridge, England. Similarly, after South Korea and Japan stamped out the disease, why has there been no further outbreaks in either of these countries, where thousands of wild Asian waterfowl winter?
This summer reprieve for the wild birds is consequently throwing more weight behind the view of the U.N. Food and Agriculture Organisation (FAO) that the unchecked trade and movement of infected poultry is the main trigger behind the spread of the lethal virus.
It is a hardy virus, Laurence Gleeson, regional manager of the FAO s Asia-Pacific office in Bangkok, told IPS. The virus is capable of surviving for three to four days outside its host in temperatures between 25 to 27 degrees (Celsius) in water or in moist environments.
And the warnings to countries hit by the virus, to monitor the movement of poultry, cover a range of activity in order to contain its spread within communities or over long distances. In addition to checking for infected poultry products, surveillance is also required on crates used to transport poultry, the manner in which poultry manure is disposed and clothes and shoes that could have come into contact with infected birds.
A lapse in such surveillance is at the root of the new strain of the H5N1 virus emerging in Thailand s north-eastern province of Nakhon Phanom and also across the Mekong River which serves as the international border in Vientiane, the capital of neighbouring Laos. This strain of bird flu, moreover, is similar to isolates from southern China, suggesting that the virus spread from China to Thailand and Laos, states the FAO.
FAO recognises that poultry trade across borders is continuing in South-east Asia and East Asia despite well-known risks to the governments and people in the region, the U.N. agency adds.
The new H5N1 strains in Thailand and Laos have distinct genetic make up that betray their origin. There are three broad clusters of the virus and sub-clusters, says Gleeson. The new virus strain in Nakhon Phanom was different to the strain that has been circulating in Thailand since 2004.
Gleeson attributes human activity, rather than migratory birds, to the spread of bird flu in Indonesia, which has suffered the highest number of human fatalities due to avian influenza. It is pretty clear the virus spread in Indonesia is because of poultry products being moved and not because of wild birds.
According to the World Health Organisation (WHO), 46 people have died after being infected with the H5N1 strain of the virus in Indonesia, out of 60 reported cases. The most recent victim was a 35-year-old woman. The death toll brings to 141, out of 241 reported cases, the number of people bird flu has killed across the world.
South-east Asia remains the epicentre of the disease. Vietnam has seen 42 deaths, Thailand has had 16 deaths and Cambodia six, according to the Geneva-based health agency. China, with 14 deaths, is the other East Asian country affected.
The bird flu virus has been detected in over 50 countries, including Burma and Malaysia, and, according to the FAO, some 200 million poultry have been culled, causing losses of ten billion dollars in Southeast Asia alone.
Yet, two-and-a-half-years after the current outbreak began, the virus has not mutated to one that has worried public health experts becoming a virus passed between humans that could trigger a pandemic.
The virus is constantly evolving. There are different little clusters established in different geographic zones, says Gleeson. At this stage, there is no significant change that is worrying.
