Leptospira Serovars for Diagnosis of Leptospirosis in Humans and Animals in Africa: Common Leptospira Isolates and Reservoir Hosts

The burden of leptospirosis in humans and animals in Africa is higher than that reported from other parts of the world. However, the disease is not routinely diagnosed in the continent. One of major factors limiting diagnosis is the poor availability of live isolates of locally circulating Leptospira serovars for inclusion in the antigen panel of the gold standard microscopic agglutination test (MAT) for detecting antibodies against leptospirosis. To gain insight in Leptospira serovars and their natural hosts occurring in Tanzania, concomitantly enabling the improvement of the MAT by inclusion of fresh local isolates, a total of 52 Leptospira isolates were obtained from fresh urine and kidney homogenates, collected between 1996 and 2006 from small mammals, cattle and pigs. Isolates were identified by serogrouping, cross agglutination absorption test (CAAT), and molecular typing. Common Leptospira serovars with their respective animal hosts were: Sokoine (cattle and rodents); Kenya (rodents and shrews); Mwogolo (rodents); Lora (rodents); Qunjian (rodent); serogroup Grippotyphosa (cattle); and an unknown serogroup from pigs. Inclusion of local serovars particularly serovar Sokoine in MAT revealed a 10-fold increase in leptospirosis prevalence in Tanzania from 1.9% to 16.9% in rodents and 0.26% to 10.75% in humans. This indicates that local serovars are useful for diagnosis of human and animal leptospirosis in Tanzania and other African countries.

非洲人类与动物的钩端螺旋体病（Leptospirosis）负担高于世界其他地区的报告数据。然而，该大洲并未对该病开展常规诊断。制约该病诊断的主要因素之一，是难以获取当地流行的钩端螺旋体血清型活分离株，无法纳入检测钩端螺旋体病抗体的金标准显微镜凝集试验（Microscopic Agglutination Test, MAT）的抗原组合中。为解析坦桑尼亚境内流行的钩端螺旋体血清型及其自然宿主，同时通过纳入新鲜本地分离株优化MAT检测方法，研究团队从1996至2006年采集的小型哺乳动物、牛和猪的新鲜尿液及肾脏匀浆中，共获得52株钩端螺旋体分离株。研究通过血清群分型、交叉凝集吸收试验（Cross Agglutination Absorption Test, CAAT）及分子分型对分离株进行鉴定。常见钩端螺旋体血清型及其对应动物宿主如下：Sokoine（牛、啮齿类）、Kenya（啮齿类、鼩鼱）、Mwogolo（啮齿类）、Lora（啮齿类）、Qunjian（啮齿类）、Grippotyphosa血清群（牛），以及来自猪的未知血清群。在MAT中纳入本地血清型（尤其是Sokoine血清型）后，坦桑尼亚的钩端螺旋体病患病率出现10倍增长：啮齿类从1.9%升至16.9%，人类从0.26%升至10.75%。这表明，本地血清型可用于坦桑尼亚及其他非洲国家的人类与动物钩端螺旋体病诊断。