宮崎県下に生息するテンの宮崎肺吸虫感染について

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　肺吸虫は人畜共通の寄生虫であるが,どちらかと言うと動物が主である.ところで本邦における野獣の肺吸虫寄生例はイタチが断然多く,同じ食肉目のイタチ科に属するテンの寄生報告はわずか2･3に過ぎない. これはテンの肺吸虫寄生率が低いためではなく, 従来あまり調査が行なわれなかったことによるものであろう.今回, われわれの実施した検索において15.4% の寄生率を示したことからも,テンはイタチに劣らず肺吸虫の主要な自然終宿主であることが立証された.　ところで供試テンに寄生を認めた虫体は宮崎肺吸虫と同定されたが,従来,宮崎肺吸虫の侵淫については全く未知であった宮崎県下のテンに本種を検出したことから,宮崎県をわが国における宮崎肺吸虫の新しい分布地として追加する.今般の供試テンの捕獲地はおおむね宮崎県内を流れる河川の上流域であり,付近の山野に生息していたテンがたまたま川畔に現れ,感染ガニ(宮崎肺吸虫の幼虫を保有するサワガニ)を捕食することにより感染が成立したものと考える.1) Autopsy was performed on 26 Japanese martens, Martes melampus melampus captured in various areas of Miyazaki Prefecture, Japan, in the past hunting season (November, 1974, to February, 1975). As a result, worm cysts produced by lung flukes were detected from the lung in four (15.4%) of these martens. Each marten was examined for the location and number of worm cysts. In Case 1, there was one cyst in each four lobes which were posterior and accessory lobes of the right lung and anterior and posterior lobes of the left lung. In Case 2, two cysts were in the posterior lobe of the left lung. In Case 3, three cysts were in the posterior lobe of the right lung and one cyst was in the posterior lobe of the left lung. In Case 4, one cyst was in the posterior lobe of the left lung. Then the number of flukes harbored in the cyst was examined in each case. In Case 1, a total of twelve flukes were harbored in the four cysts. In Case 2, a total of three flukes were harbored in the two cysts. In Case 3, a total of eight flukes were harbored in the four cysts. In Case 4, two flukes were harbored in the cyst. In brief, a total of 25 flukes were harbored in a total of 11 cysts in the four martens. When summarized by the pulmonary lobe, nine cysts harboring 19 flukes were found in the posterior lobes of both lungs. Therefore, it was clarified that the posterior lobe was more readily affected with lung flukes than any other lobe. 2) In flukes collected from the lungs examined, the cuticular spines were spaced singly and the ovaries branched rather complicatedly. The testis was large in size. When fluke eggs contained in worm cysts were examined, they were bisymmetrical and ellipsoid or ovoid. The maximum width of the shell was found in the middle of the egg in many of them. The side part of the egg shell was thin, or 1.08 (0.75 ～ 1.80) microns in thickness. The non-operculated end was not hypertrophic. When 100 fluke eggs were measured, they were 71.1～ 88.3 × 38.6～ 57.0 microns in size. When the mean and standard deviation was calculated, the longer diameter was 77.2±3.5 microns and the shorter diameter 47.4±3.4 microns. Judging collectively from all the data mentioned above, the lung fluke studied was identified as Paragonimus miyazakii Kamo, Nishida, Hatsushika et Tomimura, 1961. 3) In Japan, this fluke has been known to be distributed in the following thirteen prefectures: Ehime, Fukuoka, Hyogo, Kochi, Kumamoto, Kyoto, Nagasaki, Nara, Oita, Saga, Shizuoka, Tokushima and Yamaguchi. In Miyazaki Prefecture, Paragonimus westermani and P. ohirai have been known to be distributed, but nothing had been known at all about P. miyazakii. As the result of examination of the martens captured, it was possible to count this prefecture as the fourteenth one of Japan where P. miyazakii is distributed. 4) Of the martens examined, Nos. 1 and 2 were captured in the Kibana area in the suburbs of Miyazaki City, No.3 was in the suburbs of Kobayashi City, Miyazaki Prefecture, and No.4 in the vicinity of Aya-cho, Higashi Morokata County, Miyazaki Prefecture. The Kiyotake River flows through the Kibana area. The suburbs of Kobayashi City are located in the basin of the upper stream of the Oyodo River, the largest river in Miyazaki Prefecture. The area of Aya-cho where marten No.4 was captured is located between the Ayakita and Ayaminami River. It is presumed that Japanese martens living in the basins or valleys of these rivers may have incidentally come down to the rivers and eaten the crab Potamon dehaani which harbored metacercariae of P. miyazakii, and then they may have infected with the Paragonimiasis.

著者

芦沢広三
宮崎大学農学部家畜病理学教室

宮崎県下に生息するテンの宮崎肺吸虫感染について

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