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Transmission of avian influenza A

Cats could cause a pandemic of bird flu in humans, according to a new study. Research published in Science found that domestic cats can become infected with avian influenza A (H5N1) virus by feeding on infected birds or by associating with an infected cat. The authors say this could have important implications for transmission of the virus in humans. 'Cats may form an opportunity for this avian virus to adapt to mammals, thereby increasing the risk of a human influenza pandemic,' they conclude, informs Medical News Today. According to CIDRAP News, House cats can acquire H5N1 avian influenza and pass it on to other cats, Dutch researchers reported this week. Last February two cats in Thailand reportedly died of H5N1 avian flu, but yesterday's article in the online edition of Science apparently is the first report of cats being experimentally infected with the virus and then spreading it to other cats. Researchers sprayed H5N1 virus into the throats of three cats, according to the report by Thijs Kuiken and colleagues from Erasmus Medical Center in Rotterdam, Netherlands. The virus sample had been isolated from a Vietnamese person who died of the disease. The cats had a fever just 1 day after being exposed to the virus and were excreting virus after 3 days, though in relatively low amounts, the report says. One cat died 6 days after exposure. Two other cats were put in contact with the first group 2 days after the latter had been infected. In addition, the researchers fed infected chicks to three more cats. All of the additional cats became ill with signs like those of the first group. Three other cats were exposed to influenza A (H3N2), a common human strain, and stayed healthy. After the infected cats were euthanized, necropsy showed they had diffuse alveolar damage like that caused by H5N1 infection in humans and monkeys, the report says. The findings suggest that "the role of cats in the spread of H5N1 virus between poultry farms, and from poultry to humans, needs to be re-assessed," the researchers write. In addition, "Cats may form an opportunity for this avian virus to adapt to mammals, thereby increasing the risk of a human influenza pandemic." Reuters reports that cats can get the avian influenza virus decimating bird flocks across Asia, which means pets are at risk of getting and spreading the disease -- and may serve as a mixing pot for dangerous new mutations, Dutch researchers reported on Thursday. In an experiment, cats caught the H5N1 flu virus by breathing it in and by eating infected chicks, the team of virus experts at Erasmus Medical Center in Rotterdam said. "This is extraordinary, because domestic cats are generally considered to be resistant to disease from influenza A virus infection," the researchers reported in Friday's issue of the journal Science. The H5N1 strain of bird flu virus has killed 27 people in Vietnam and Thailand in 2003 and 2004. It has also killed or forced the destruction of millions of birds, many of them small flocks kept by farmers. It pops up in unexpected places and has been recently found in Malaysia and Indonesia, spread by unknown means.

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