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Bird flu
takes flight from its Asian roosts
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EVEN as it crops up in the far corners of Europe and Africa, the virulent bird flu that raised fears of a human pandemic has been largely snuffed out in the parts of Southeast Asia where it claimed its first and most numerous victims. Health officials are pleased and excited. “In Thailand and Vietnam, we’ve had the most fabulous success stories”, said Dr David Nabarro, chief pandemic flu co-ordinator for the United Nations. Vietnam, which has had almost half of the human cases of A(H5N1) flu in the world, has not seen a single case in humans or a single outbreak in poultry this year. Thailand, the second-hardest-hit nation until Indonesia recently passed it, has not had a human case in nearly a year or one in poultry in six months. Encouraging signs have also come from China, though they are harder to interpret. These are the second positive signals that officials have seen recently in their struggle to prevent avian flu from igniting a human pandemic. Confounding expectations, birds making the spring migration north from Africa have not carried the virus into Europe. Dr Nabarro and other officials warn that it would be highly premature to declare any sort of victory. The virus has moved rapidly across continents and is still rampaging in Myanmar, Indonesia and other countries nearby. It could still hitch-hike back in the illegal trade in chicks, fighting cocks or tropical pets or in migrating birds. But this sudden success in the former epicenter of the epidemic is proof that aggressive measures like killing infected chickens, inoculating healthy ones, protecting domestic flocks and educating farmers can work. Dr Nabarro said he was “cautious in interpreting these shifts in patterns” because too little is known about how the disease spreads. Other officials agreed. While Vietnam began vaccinating all its 220 million chickens last summer, Thailand did not because it has a large poultry export industry, and other nations would have banned its birds indefinitely. (Vaccines can mask the virus instead of killing it). |
Instead, Thailand culled wide areas around infected flocks, compensated farmers generously and deputized a volunteer in every village to report sick chickens. It vaccinates fighting cocks, which can be worth thousands of dollars, and even issues them passports with their vaccination records so they can travel, Dr Nabarro said. Government inspectors sample birds everywhere; in February, Thailand reported that samples from 57,000 birds had come back negative. According to Dr Klaus Stohr, a flu specialist at the World Health Organization, Thailand and Vietnam also delivered the anti-viral drug Tamiflu to even the smallest regional hospitals and told doctors to treat all flu patients even before laboratory diagnoses could be made. Dr Nabarro particularly praised the leaders of the two countries for ordering high-level officials to fight the disease, and for making sure that enough cash to entice farmers to hand over their birds for culling flowed down official channels without being siphoned off. Hints suggest that the disease is also being beaten back in China, the country where it is assumed to have begun. International officials tend to greet official public health reports from China skeptically, in part because it concealed the outbreak of the SARS virus there for months. It did not officially report any bird cases for years, even though many scientists contend the virus incubated there between its first appearance in humans in Hong Kong in 1997 and the current human outbreak, which began in Vietnam in 2003. Some top Chinese officials have blamed the reluctance of local officials to report bad news to Beijing. Dr Nabarro said he met a vice-premier “who made it clear they are absolutely determined to get the fullest possible co-operation from provincial authorities”. China’s reported human cases have remained low: eight last year and 10 this year. Perhaps more important, its poultry cases --- which lead to human cases and increase the risk of a mutant pandemic strain --- seem to be dropping. According to the WHO, China said it had outbreaks in 16 provinces in |
2004. Last year, it reported outbreaks in only 12 provinces, but one in November was so large, 2.5 million birds were culled to contain it. After that, the Agriculture Ministry announced that it would vaccinate every domestic bird in China, which raises and consumes 14 billion chickens, ducks and geese each year. The official news agency reported about the same time that a fake flu vaccine, possibly with live virus in it, might have spread the disease. Dr Stohr, who is in charge of WHO flu vaccine efforts, said he was told by Chinese agriculture officials that the country was now producing 46 billion doses of poultry vaccine a year, and was supplying vaccines to Vietnam. China’s most recent monthly reports describe smaller outbreaks than were previously common: findings of a few dead wild birds and culls of 126,000 birds in one spot and 16,000 in another, for example. In Cambodia and Laos, which separate Thailand and Vietnam, the situation is vague. Laos has reported no human cases and last reported poultry outbreaks two years ago. Cambodia’s reported human cases dropped to two this year, from four last year. No poultry outbreaks were reported, but surveillance is so spotty that some must have occurred and gone unnoticed, Dr Wantanee Kalpravidh, chief of flu surveillance in Southeast Asia for the United Nations Food and Agricultural Organization said. Cambodia was slow to compensate farmers for their birds because of problems with corruption in a previous cash-for-guns programme. Where the Southeast Asian governments have taken action, however, the risk of the virus returning is ever present, Dr Nabarro said. For example, he said, it probably exists in Vietnam in Muscovy ducks, which can harbor the virus but do not get sick, and it has turned up in isolated birds in open-air markets near the Chinese border. (Single birds do not constitute an outbreak). Since Chinese farmers can get three times as much for a chicken in Vietnam as they can get at home, the temptation to smuggle persists. “Tomorrow, the whole thing could change again”, Dr Nabarro said. “We need to be on the alert at all times”. --- NYT. |
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