Swedish Defense Research Agency, Umea, Sweden.
Emerg Infect Dis. 2009 Dec;15(12):1937-47. doi: 10.3201/eid1512.090487.
Summer outbreaks of tularemia that occurred from 1995 through 2005 in 2 locations in Sweden affected 441 persons. We performed an epidemiologic investigation of these outbreaks using a novel strategy, involving high-resolution genotyping of Francisella tularensis isolates obtained from 136 patients (using 18 genetic markers developed from 6 F. tularensis genome sequences) and interviews with the patients. Strong spatial associations were found between F. tularensis subpopulations and the places of disease transmission; infection by some subpopulations occurred within areas as small as 2 km(2), indicating unidentified environmental point sources of tularemia. In both locations, disease clusters were associated with recreational areas beside water, and genetic subpopulations were present throughout the tularemia season and persisted over years. High-resolution genotyping in combination with patients' statements about geographic places of disease transmission provided valuable indications of likely sources of infection and the causal genotypes during these tularemia outbreaks.
1995 年至 2005 年期间，瑞典的两个地点爆发了夏季土拉菌病疫情，共影响了 441 人。我们采用一种新策略对这些疫情进行了流行病学调查，对从 136 名患者中分离出的土拉弗朗西斯菌（使用从 6 株土拉弗朗西斯菌基因组序列中开发的 18 个遗传标记）进行了高分辨率基因分型，并对患者进行了访谈。发现土拉弗朗西斯菌亚群与疾病传播地点之间存在很强的空间关联；某些亚群的感染发生在面积仅 2 平方公里（2）的区域内，表明土拉菌病存在未识别的环境点状传染源。在两个地点，疾病集群都与水旁的娱乐区有关，而且整个土拉菌病季节都存在遗传亚群，并持续多年。高分辨率基因分型结合患者对疾病传播地理地点的陈述，为这些土拉菌病疫情期间可能的感染源和致病基因型提供了有价值的线索。
