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Hunting the carriers

发布时间:2019-03-08 01:02:04来源:未知点击:

By Ian Anderson A VIRUS that has already killed some 80 people in Malaysia could be lurking in a range of domestic animals, complicating efforts to contain the new disease. Pigs appear to be the main source of the deadly encephalitis, and hundreds of thousands are being slaughtered in an attempt to control the outbreak (This Week, 3 April, p 4). But the virus has also been found in a dog, and virologists suspect it could be present in other pets and livestock. “It may turn out to have a remarkable ability to go across species,” says Brian Mahy, director of the Division of Viral and Rickettsial Diseases at the US Centers for Disease Control and Prevention (CDC) in Atlanta. The virus responsible has been named Nipah, after the region in the state of Negeri Sembilan where it was first isolated. It is similar to a less contagious virus found in fruit bats in Australia, which killed two people in 1994 and 1995. A 10-strong CDC team is helping researchers at the University of Malaya in Kuala Lumpur to investigate the outbreak. They are analysing stored blood samples taken from pigs, following suggestions that the Nipah virus has been present in Malaysia’s pig farms since 1997 or earlier. But as yet the researchers have no idea why it has only now become a major problem. “What caused it to amplify is not clear,” says Mahy. A postmortem on a dog found dying in a ditch in southern Malaysia has confirmed that it was killed by the Nipah virus, says Mahy. It is too early to determine the significance of this finding, but anecdotal evidence suggests that other domestic animals have been affected by the disease. Blood samples are now being taken from dogs, cats, goats, chickens and cows. And around 2000 samples from thoroughbred horses in Malaysia and Singapore have been analysed by the Australian Animal Health Laboratory at Geelong near Melbourne. The horse-racing industry is worried that the disease will spread to its animals, as the related Australian virus killed horses. However, the samples from thoroughbreds have all tested negative. Fruit bats are also being investigated as a possible reservoir of the disease. Hume Field of the Department of Primary Industry in Queensland has collected serum samples from more than 300 bats near Ipoh in northern Malaysia. No vaccine exists for the Nipah virus. As well as causing encephalitis, the virus leads to breathing problems. People with the disease are being treated with ribavirin, a drug used to combat respiratory viral infections,