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　　This year, a dangerous strain1 of avian influenza,2 or bird flu, was confirmed3 in eight Asian countries. The disease, whose symptoms include coughing, fever, and a headache, has already killed many people. Officials in the affected countries responded by killing millions of chickens, which financially devastated4 chicken farmers.

　　The H5N1 subtype of avian influenza currently attacking Asia is the only known strain capable of infecting humans. Health officials are concerned that H5N1 could mutate5 after mixing with human genes and create the next flu pandemic.6 Most of the deaths from the current outbreak, however, have been traced to contact with sick birds. There have been no confirmed cases of human-to-human transmission.7

　　Vocabulary

　　1. strain n. (菌)株

　　2. avian influenza n. 禽流感

　　3.confirm v. 证实

　　4.devastate v. 损害；摧毁

　　5.mutate v. 突变；变异

　　6.pandemic n. (广泛蔓延的)流行病

　　7.transmission n. (疾病等的)传播