Department of Bacteriology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
Section of Microbiology, Mie Prefecture Health and Environment Research Institute, 3684-11 Sakura-cho, Yokkaichi-shi, Mie 512-1211, Japan.
J Med Microbiol. 2013 Apr;62(Pt 4):630-636. doi: 10.1099/jmm.0.050039-0. Epub 2012 Dec 21.
Canine leptospirosis, which is caused by infection with pathogenic Leptospira species, occurs worldwide, but information regarding the causative Leptospira serotypes and genotypes and their effects on virulence in dogs remains limited. Monitoring acute leptospirosis in dogs as sentinels can also aid in estimating the risk of human leptospirosis, particularly when the disease is rare, as it currently is in Japan. Among 283 clinically suspected cases of leptospirosis diagnosed from August 2007 to March 2011 in Japan, 83 cases were laboratory diagnosed as leptospirosis by blood culture, a rise in antibody titres in paired sera using a microscopic agglutination test (MAT) and/or DNA detection using flaB-nested PCR. The infected dogs comprised hunting dogs (31 dogs) and companion animals (50 dogs) and two unknown; 63.4 % of the infected dogs were males. The mortality rate was 53.2 %. A rise of at least fourfold in MAT titre was detected in 30 dogs whose paired serum samples were obtained, and the predominant reactive serogroup was Hebdomadis (53.3 %), followed by Australis (16.7 %) and Autumnalis (16.7 %). Leptospira interrogans was isolated from 45 dogs of the following serogroups: Australis (16), Autumnalis (six), Canicola (one), Hebdomadis (21) and Icterohaemorrhagiae (one). All of these serogroups caused lethal infections (57.1-100 %). Genetic heterogeneity was demonstrated in serogroups Australis, Autumnalis and Hebdomadis by multilocus sequence typing (MLST) and/or RFLP analysis based on PFGE. In serogroup Hebdomadis, each genotype determined by MLST had a unique mortality rate in the infected dogs. Although classic canine leptospirosis is associated with serovars Canicola and Icterohaemorrhagiae, serogroup Hebdomadis has become the predominant serogroup causing high mortality in Japan. This study suggests that the virulence of members of serogroup Hebdomadis in dogs may be associated with the genotypes in this serogroup.
犬钩端螺旋体病是由致病性钩端螺旋体感染引起的，发生在世界各地，但有关致病钩端螺旋体血清型和基因型及其对犬类毒力的影响的信息仍然有限。监测犬类作为哨兵的急性钩端螺旋体病也有助于估计人类钩端螺旋体病的风险，特别是在疾病罕见的情况下，如目前在日本。在 2007 年 8 月至 2011 年 3 月期间，日本共诊断出 283 例疑似钩端螺旋体病的临床病例，其中 83 例通过血液培养、使用显微镜凝集试验 (MAT) 检测配对血清中抗体滴度升高和/或使用 flaB-嵌套 PCR 检测 DNA 确诊为钩端螺旋体病。受感染的犬包括猎犬（31 只）和伴侣动物（50 只）和两只不明；感染犬中雄性占 63.4%。死亡率为 53.2%。在获得配对血清样本的 30 只犬中，至少有 4 倍的 MAT 滴度升高，主要反应血清群为 Hebdomadis（53.3%），其次是 Australis（16.7%）和 Autumnalis（16.7%）。从以下血清群的 45 只犬中分离出钩端螺旋体 interrogans：Australis（16 只）、Autumnalis（6 只）、Canicola（1 只）、Hebdomadis（21 只）和 Icterohaemorrhagiae（1 只）。所有这些血清群都引起了致命感染（57.1-100%）。通过多位点序列分型（MLST）和/或基于 PFGE 的 RFLP 分析，在血清群 Australis、Autumnalis 和 Hebdomadis 中显示出遗传异质性。在血清群 Hebdomadis 中，通过 MLST 确定的每个基因型在感染犬中都有独特的死亡率。虽然经典的犬钩端螺旋体病与 Canicola 和 Icterohaemorrhagiae 血清型有关，但血清群 Hebdomadis 已成为导致日本高死亡率的主要血清群。本研究表明，血清群 Hebdomadis 成员在犬类中的毒力可能与其在该血清群中的基因型有关。
