1999年8月下旬,在纽约市暴发了西尼罗病毒(WNV)引起的脑炎。此后在周围城市亦发现了该病,对此有关的城市开展了大范围的控制蚊子行动以降低感染的危险。纽约市采取预防行动后未发现人WNV感染,而有些城镇由于没有控制蚊子而不断有人WNV感染的报告。这一结果提示该预防行动降低了人感染的危险性。 2000年5月国家疾病控制中心(CDC)发布了有关指南以指导全国的监测、预防和控制工作,并建 Encephalitis caused by West Nile virus (WNV) outbreak in New York City in late August 1999. Since then, the disease has also been found in the surrounding cities, and a wide range of mosquito control activities have been conducted in the cities concerned to reduce the risk of infection. No human WNV infection was detected in New York City following preventive action, while reports of WNV infection continued in some towns due to lack of mosquito control. This result suggests that this preventive action reduces the risk of human infection. In May 2000, the National Center for Disease Control (CDC) released guidelines to guide the nation’s monitoring, prevention and control efforts and to build