1994 Fiscal Year Final Research Report Summary
Epidemiologic and pathogenetic study of Lyme borreliosis
| Project/Area Number |
04671391
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
医学一般
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| Research Institution | Shinshu University |
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Principal Investigator |
UCHIKAWA Kimito Shinshu University School of Medicine, Department of Parasitology Associate Professor, 医学部, 助教授 (90020768)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMA Hidenori Shinshu University School of Medicine, Department of Public Health Lecturer, 医学部, 講師 (50207859)
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| Project Period (FY) |
1992 – 1994
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| Keywords | Lyme borreliosis / Haemaphysalis / Ixodes / Borrelia / Pathogenicity / C3H / HeJ mouse / Gerbil / Reservoir |
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| Research Abstract |
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.
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