Epidemiologic and pathogenetic study of Lyme borreliosis

约50只血蜱成虫。来自Tanzawa的人没有感染莱姆病疏螺旋体。因此，我们认为血蜱不会在日本莱姆病的流行病学中发挥任何作用，尽管其他工作人员已从黄色血蜱中分离出一种疏螺旋体。来自田间的全沟硬蜱未进食幼虫未感染疏螺旋体，证实了日本疏螺旋体经卵传播的阴性结果。通过M.Nakao的努力，从长野县的全沟I.persulcatus和小型哺乳动物中分离的疏螺旋体的基因种被鉴定。这些调查的结果揭示了莱姆病在长野县的流行病学。通过将来自全沟硬蜱和卵形硬蜱的疏螺旋体腹膜内接种到C3 H/HeJ小鼠中来检查它们的致病性。证明两种蜱的疏螺旋体对该品系小鼠具有弱致病性。利用对疏螺旋体感染敏感性最高的沙鼠，证实：1）全沟硬蜱和卵形硬蜱的疏螺旋体均具有致病性; 2）卵形硬蜱的疏螺旋体致病性较弱; 3）目前卵形硬蜱的疏螺旋体致病株仅分布于一个地区。1992-1994年共收治蜱叮咬145例，其中20例临床诊断为莱姆病。利用上述研究结果和其他可用数据，蜱叮咬和莱姆病在日本的特点进行了讨论。

About 50 adult ticks of Haemaphysalis spp. from Tanzawa were free from Lyme borrelia infection. Thus, we thought that Haemaphysalis ticks would not play any role in the epidemiology of Lyme borreliosis in Japan, although a single strain of borrelia has been isolated from H.flava by other workers. Unfed larvae of Ixodes persulcatus from the field were not infected with the borrelia, confirming the negative results of transovarial transmission of borreliae in Japan. Through the efforts of M.Nakao, genospecies of borreliae isolated from I.persulcatus and small mammals in Nagano Prefecture were identified. The results of these investigations shed light on the epidemiology of Lyme borreliosis in Nagano Prefecture. Pathogenicity of borreliae from I.persulcatus and I.ovatus was checked by inoculating them intraperitoneally into C3H/HeJ mice. The borreliae from both ticks were proved to be weakly pathogenic to this strain of mice. Using gerbils that are more sensitive to borrelial infection than any mouse, it was confirmed as follows : 1) the borreliae from both I.persulcatus and I.ovatus were pathogenic, 2) pathogenicity of the borrelia from I.ovatus was weaker, and 3) distribution of pathogenic strains of borreliae from I.ovatus was restricted to one area at present. During 1992-1994, we were introduced a total of 145 cases of tick bite, of which 20 were diagnosed clinically as having Lyme borreliosis. Using the above findings and other available data, characteristic features of tick bite and Lyme borreliosis in Japan were discussed.