Surveillance results of plague in Yunhe county, Zhejiang province,2000-2007

ObjectiveTo detect plague outbreaks between humans and between animals in a timely manner based on the surveillance of plague in the areas with epidemic history. MethodsFixed and mobile surveillance stations were established in the originally plague-endemic areas to measure the indoor and outdoor density of rats, body fleas of rats and ground free fleas; organ samples were collected from captured live rats for bacteriological isolation and culture, blood samples taken for F1 antibody detection. ResultsThe average indoor and outdoor density was 3.50% and 3.60%, respectively; the average flea- carrying rate 8.55%, and the total flea index 0.130. The predominant indoor and outdoor species were IRattus norvegicus/I and IApodemus agrarius/I, respectively, rat body fleas consisting of IMonopsyllus anisus and Cosmopolitan mouse/I flea. IXenopsylla cheopis/I was not detected. A total of 3551 live captures were isolated for bacteria, though noIYersinia pestis/I was identified. Indirect hemagglutination assay of 6511 sera samples also resulted in negative cultures. Radioimmunoprecipitation assay and gold marking suggested a positive serum from in eleven samples. ConclusionDespite negative isolation of IYersinia pestis,/I the eight-year systematic surveillance identified one RIA-positive serum, suggesting potential risk of plague epidemic in Yunhe county. Therefore, surveillance on plague shall be strengthened in order to prevent the occurrence of plague epidemic.