The speed at which bird flu can spread in today's high-density poultry farms mean that once an infection breaks out, all the birds on a farm may have to be slaughtered. This is not only a blow to farmers, but also attracts criticism from animal welfare campaigners. (photo by Jimmy Lin) (photo by Jimmy Lin)

In mid-February, as temperatures gradually began to rise again, the spate of warnings about avian influenza that had been filling the pages of the newspapers also began to abate. However, the succession of bird flu outbreaks that have affected South Korea, Vietnam, mainland China, and various countries in Southeast Asia over the winter have already led to the culling of hundreds of thousands of chickens, ducks and other poultry, and have caused nearly 20 human deaths. Coming on the heels of the SARS crisis, this new viral attack on Asia is not only potentially disastrous for poultry farmers, but is also disrupting industries such as catering and tourism. Do the outbreaks herald a global flu pandemic? How can they be brought under control? These are the challenges that are facing disease control experts.

For older people, reports of "fowl pest" are nothing new. But when fowl pest-avian influenza-infects and even kills people, this is a sign that the virus is mutating and becoming more virulent, which for epidemiologists is a nightmare scenario.

In 1997, the death of a three-year-old boy in Hong Kong raised the curtain on "human bird flu." The child died of acute pneumonia after being infected with the H5N1 strain of the influenza A virus, which had previously only affected poultry. The suspected source of the infection was traced back to poultry in southern China, a region that has been the source of several global pandemics of influenza in the past. Fortunately, the outbreak was nipped in the bud by the Hong Kong authorities' swift action in slaughtering almost 1.5 million birds.

This winter, bird flu has made a comeback, but this time it threatens a much larger area, stretching the length of East Asia from South Korea and Japan in the north to Indochina in the south. By 10 February 2004 there had been 23 cases of human infection with the H5N1 virus worldwide, with 18 deaths. This demonstrates the great potency and lethalness of H5N1.

In the region threatened by bird flu, Taiwan alone has remained clean. There have been sporadic outbreaks of fowl pest around the island, but thus far they have all involved the less pathogenic and less virulent H5N2 virus strain, which does not infect humans. This is why, with the massive cull of poultry leading to a shortage of chickens in several Asian countries, Taiwanese chickens have unexpectedly become much sought after, with orders coming in from various neighboring territories.

Although the impact of bird flu in Taiwan has so far been much less severe than elsewhere, the presence of the more virulent virus strain in so many nearby countries, rampant smuggling of poultry across the Taiwan Strait and the movement of large numbers of wild birds in and out of the island on their winter migrations mean that Taiwan remains under threat. Based on previous experience in the USA and Italy, if the weaker H5N2 strain is present in the environment, it is likely to mutate into the stronger H5N1 strain within six months. Furthermore, if pigs that happen to be infected with a human influenza virus also become infected with a bird flu virus, genes can easily be exchanged between the viruses, and in this way a new human "super-flu" might emerge that can be transmitted directly from person to person, rather than only being caught from poultry or livestock. If this happens, we may be in for a repeat of the tragic flu pandemic of 1918 that killed 20 million people worldwide.

This is why disease control agencies in Taiwan are on a high state of alert, and insist on "complete eradication" whenever a bird flu infection is discovered in poultry such as chickens or ducks. As of 10 February, outbreaks had occurred in seven counties and cities islandwide, including Changhua, Tainan and Chiayi. Infected poultry farms are not only subject to a complete cull, but are forbidden from raising new birds for six months, after which they may raise a small number for special testing. They may only resume normal operation once they test completely virus free.

Experts warn that to effectively prevent and eradicate bird flu, it is necessary to change the way poultry are raised and slaughtered, on the one hand by avoiding the use of high-density poultry sheds in which tens of thousands of birds are raised together, so as to reduce the speed at which disease can spread, and on the other hand to avoid keeping chickens and ducks in close proximity to pigs, to prevent pigs becoming "mixing vessels" that foster the emergence of new, more virulent viruses. There is also a need to change Taiwanese people's preference for freshly slaughtered, unrefrigerated poultry meat, sold at traditional wet markets in areas soiled with droppings and feathers.

Following the mass slaughter of pigs in Taiwan a few years ago due to foot and mouth disease, last year's ban on the import of American beef due to mad cow disease, and the collapse of the market for Scandinavian salmon due to traces of environmental toxins, the current outbreak of disease in poultry once again highlights how in seeking to sate our appetite for good food we humans not only pay a price in terms of our own health, but also repeatedly bring disaster to animals. Perhaps this crisis presents us with an opportunity to reconsider our relationship with the environment, and with other living beings.