Department of Comparative Pathobiology, School of Veterinary Medicine, Purdue University, 725 Harrison Street, West Lafayette, IN 47907-2027, United States.
Prev Vet Med. 2010 Aug 1;96(1-2):122-31. doi: 10.1016/j.prevetmed.2010.05.017. Epub 2010 Jun 26.
Leptospirosis is a re-emerging disease of dogs in the United States (U.S.). This paper reports the findings of a retrospective study conducted to determine if seroreactivity to Leptospira microscopic agglutination test (MAT) among dogs in the U.S. clustered in space and time. The study utilized canine sera submitted to a commercial laboratory for leptospiral MAT from January 2000 through December 2007. There were 31,869 serum samples submitted by veterinarians from 3156 zip code locations across the U.S. Results of MAT were considered positive at titers of > or = 1:1600. Spatial and spatial-temporal scan statistics were used to identify statistically significant clusters of seroreactivity to Leptospira (overall and individual serovars) using recorded test request dates and locations of the centroid of the zip code reported for each serum sample. There were 2469 positive MAT results with a titer > or = 1:1600 to at least one of seven Leptospira serovars. Two relevant spatial clusters of 26.3 and 246.5 km radius were identified (P=0.001). The primary cluster was located in the northeastern part of Illinois including Chicago and surrounding areas (232 [14.4%] of 1612 MAT positive; RR=1.95). The secondary cluster covered the central part of Texas (292 [12.62%] of 2314 MAT positive; RR=1.71). Eight space-time clusters of overall MAT positivity were identified (29-335 km radius; P=0.001-0.048 and RR=3.98-24.69) that covered different geographic locations for different time points. Spatial and space-time clusters for individual serovars were also identified for six serovars: eight each of Grippotyphosa and Pomona, seven of Bratislava, five of Autumnalis, and three each of Icterohaemorrhagiae and Canicola. In conclusion Leptospira seropositivity in dogs tended to have distinctive clusters in space and space-time. Most of the space-time clusters of overall Leptospira MAT seropositivity were associated with cluster events for individual serovars. Further investigation is warranted to explain individual serovar clusters detected in this study, as a complex interaction of incidental host, environment and reservoir host may be responsible for the occurrence of these serovar clusters.
钩端螺旋体病是美国（美国）重新出现的犬类疾病。本文报告了一项回顾性研究的结果，该研究旨在确定美国犬类对钩端螺旋体微量凝集试验（MAT）的血清反应是否在空间和时间上聚集。该研究利用了 2000 年 1 月至 2007 年 12 月期间一家商业实验室提交的犬血清进行了研究。兽医从美国 3156 个邮政编码地区提交了 31869 个血清样本。MAT 结果的滴度为 >或= 1:1600 被认为是阳性的。使用记录的测试请求日期和每个血清样本报告的邮政编码中心的位置，使用空间和时空扫描统计数据来识别对钩端螺旋体（总体和个别血清型）的血清反应的统计学显著聚集。有 2469 份阳性 MAT 结果，其滴度 >或= 1:1600 至少对七种钩端螺旋体血清型中的一种。确定了两个相关的空间集群，半径分别为 26.3 和 246.5 公里（P=0.001）。主要集群位于伊利诺伊州东北部，包括芝加哥和周边地区（232 [14.4%] 个 MAT 阳性；RR=1.95）。次要集群覆盖德克萨斯州中部（292 [12.62%] 个 MAT 阳性；RR=1.71）。确定了 8 个总体 MAT 阳性的时空集群（29-335 公里半径；P=0.001-0.048 和 RR=3.98-24.69），这些集群覆盖了不同的地理位置和不同的时间点。还确定了六个血清型的个体血清型的时空集群：每个 Grippotyphosa 和 Pomona 有 8 个，Bratislava 有 7 个，Autumnalis 有 5 个，Icterohaemorrhagiae 和 Canicola 各有 3 个。总之，狗的钩端螺旋体血清阳性倾向于在空间和时空上具有独特的集群。大多数总体 Leptospira MAT 血清阳性的时空集群与个别血清型的集群事件有关。需要进一步调查以解释本研究中检测到的个别血清型集群，因为偶然宿主、环境和储存宿主的复杂相互作用可能是这些血清型集群发生的原因。
