Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, Ontario, Canada.
Epidemiol Infect. 2012 Apr;140(4):731-43. doi: 10.1017/S0950268811001014. Epub 2011 Jun 7.
Leptospirosis is one of the most widespread zoonoses in the world. A large outbreak of suspected human leptospirosis began in Sri Lanka during 2008. This study investigated spatial variables associated with suspected leptospirosis risk during endemic and outbreak periods. Data were obtained for monthly numbers of reported cases of suspected clinical leptospirosis for 2005-2009 for all of Sri Lanka. Space-time scan statistics were combined with regression modelling to test associations during endemic and outbreak periods. The cross-correlation function was used to test association between rainfall and leptospirosis at four locations. During the endemic period (2005-2007), leptospirosis risk was positively associated with shorter average distance to rivers and with higher percentage of agriculture made up of farms <0·20 hectares. Temporal correlation analysis of suspected leptospirosis cases and rainfall revealed a 2-month lag in rainfall-case association during the baseline period. Outbreak locations in 2008 were characterized by shorter distance to rivers and higher population density. The analysis suggests the possibility of household transmission in densely populated semi-urban villages as a defining characteristic of the outbreak. The role of rainfall in the outbreak remains to be investigated, although analysis here suggests a more complex relationship than simple correlation.
钩端螺旋体病是世界上分布最广泛的动物传染病之一。2008 年，斯里兰卡发生了一起大规模疑似人间钩端螺旋体病暴发疫情。本研究调查了在地方性和暴发流行期间与疑似钩端螺旋体病风险相关的空间变量。获得了斯里兰卡 2005-2009 年所有报告的疑似临床钩端螺旋体病每月病例数的数据。时空扫描统计与回归模型相结合，以检验地方性和暴发流行期间的关联。交叉相关函数用于检验四个地点的降雨与钩端螺旋体病之间的关联。在地方性流行期间（2005-2007 年），钩端螺旋体病风险与到河流的平均距离较短和农业中农场面积小于 0.20 公顷的比例较高呈正相关。在基线期，疑似钩端螺旋体病病例和降雨的时间相关分析显示，降雨与病例之间存在 2 个月的滞后。2008 年的暴发地点的特点是到河流的距离较短和人口密度较高。分析表明，在人口稠密的半城市村庄中，家庭传播的可能性是暴发的一个特征。虽然这里的分析表明降雨与暴发流行之间的关系比简单的相关性更为复杂，但降雨在暴发流行中的作用仍有待调查。
