open access

https://hdl.handle.net/2115/57320

北海道におけるBorrelia spp.の伝播に対する鹿の役割 [全文の要約]

英語

2014-09-25

Hokkaido University

https://www.lib.hokudai.ac.jp/dissertations/copy-guides/

The intent of this research was to describe the role of deer in the transmission of different species of Borrelia spp. Sika deer (Cervus nippon yesoensis) are the hosts of ticks of various species and stages in Hokkaido. Deer overpopulation has caused problems with forestry and agricultural production. The potential of deer involvement in zoonoses is also being watched. In this study, deer caught in the nuisance control scheme and ticks collected from deer and the field were tested to detect Borrelia spp.. These results were analyzed for the following two subjects. Firstly, a survey was held related to a relapsing fever Borrelia sp. recently found in Hokkaido. A relapsing fever Borrelia sp. similar to Borrelia lonestari was detected from wild sika deer and Haemaphysalis ticks in the eastern part of Hokkaido, Japan. The total prevalence of this Borrelia sp. in tested deer blood samples was 10.6% using conventional PCR and real-time PCR methods. The prevalence was significantly higher in deer fawns compared to adults (21.9% and 9.4%, respectively). Additionally, there was a significant regional difference between two sampling areas, Shiretoko and Shibetsu with 17% and 2.8% prevalence, respectively. Regional differences were also found in tick species collected from the field and on deer. In the Shiretoko region, Haemaphysalis spp. were more abundant than Ixodes spp., while in Shibetsu, it was the opposite. Using real-time PCR analysis, B. lonestari-like was detected from 2 out of 290 adult Haemaphysalis spp. ticks and 4 out of 76 pools of nymphs. This is the first report of a B. lonestari-like organism in Haemaphysalis spp. ticks, and the first phylogenetic analysis of this B. lonestari-like organism in Asia. Based on this result, Haemaphysalis spp. are the most likely candidates to act as a vector for B. lonestari-like; furthermore, regional variation of B. lonestari-like prevalence in sika deer may be dependent on the distribution of these ticks. The second survey was on Lyme disease borreliae in deer with an aspect different from the common vector-reservoir relationship. In conclusion, it could be said that sika deer may be the zooprophylactic host for ticks harboring Lyme disease borreliae in Hokkaido.

甲第11513号

博士(獣医学)

(主査) 教授 坪田 敏男, 教授 大橋 和彦, 教授 苅和 宏明, 准教授 下鶴 倫人, 室長 川端 寛樹 （国立感染症研究所）

獣医学研究科（獣医学専攻）

博士論文

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