宮崎県下に生息するテンの肺吸虫自然感染状況について : 昭和50年度猟期における成績

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A total of 38 Japanese martens, Martes melampus melampus, caught in Miyazaki Prefecture in the 1975 hunting season (from November, 1975, to February, 1976) were examined for infection with the lung fluke, Paragonimus sp.. Macroscopical observation was also made on changes of the lungs infected with flukes. The following results were obtained. 1) Of the 38 martens examined, ten (26.3%) were found to harbor lung flukes. In the 1974 hunting season 26 martens were caught and Paragonimus infection was noticed in four of them. When the results of the 1974 and 1975 hunting seasons were combined, lung flukes were found in 14 martens (21. 9%) out of 64. Therefore, it was clarified that there was a considerably dense Paragonimus infection among Japanese martens inhabiting Miyazaki Prefecture. No detailed identification has been carried out as yet on the lung flukes detected, but most of the flukes seemed to belong to Paragonimus miyazakii Kamo, Nishida, Hatsushika et Tomimura, 1961. 2) The 38 martens were caught in (or presumed to have inhabited) a district occupying middle one-third of Miyazaki Prefecture. None of them were caught in the northern or southern one-third of the prefecture. Of the 10 martens harboring lung flukes, seven, orthe largest number, were caught in Aya-cho, Higashimorokata-gun, two in Saito City, and one in Nishimera-son, Koyu-gun. The Ayakita and Ayaminami River flow through the Aya-cho district. They are upper waters of the Oyodo River, or the largest river in the prefecture. Saito City and Nishimera-son districts are located in the basin of the Hitotsuse River, which is another important river in the prefecture. Crabs harboring Paragonimus metacercariae inhabiting the basin of the upper waters of these rivers may have been eaten by martens, which may have contracted infection with the lung flukes. 3) The parasitized lungs of the 10 martens were observed by the naked eye. The lesion of standard type which consists of a typical worm cyst was found in the lungs of 5 martens. The others changes observed were those of the type of early stage of infection represented by the incomplete formation of the wall of the worm cyst; those of the type of beginning stage of infection showing no worm cysts at all, but young small flukes about 3 mm in body length penetrating into the pulmonary tissue; and those of the type of double infection exhibiting typical worm cysts and young small flukes penetrating into the pulmonary tissue in the same lung. 4) The frequency of appearance of changes caused by Paragonimus infection was determined by the pulmonary lobe. The posterior lobe of the right lung was affected most frequently (9 martens). The accessory lobe and the posterior lobe of the left lung were affected in 5 martens each. The anterior lobe of the right lung and the anterior lobe of the left lung were affected in 4 martens each. No changes were recognized at all in the intermediate lobe of the right lung. It is of great interest to note that changes caused by Paragonimus infection appeared relatively frequently in the accssory lobe, which is the smallest of all the pulmonary lobes.　昭和50年度猟期に宮崎県下で捕獲したテン38頭中10例に肺吸虫の寄生を認めた.前年(昭和49年度)の成績を合わせると,肺吸虫の検出率は21.9% であり,県下のテンは相当濃厚な感染状況にあることが判明した. しかもその種類は宮崎肺吸虫が主であるものと推測され,公衆衛生上の見地からも重要な意義をもつと考える. 今回の寄生例を疫学的にみると,県内主要河川(大淀川及び一ツ瀬川水系)の上流域で感染したことはほぼ明らかである.　寄生肺の病理解剖学的所見から,肺吸虫の終宿主体内移行経路中,横隔膜穿通の部位について示唆を得るとともに,また肺病変の型別から肺侵入後の時日の経過を推定することができた.なお,材料中とくに若小虫の肺組織内侵入病変に遭遇したのは自然例では貴重と考える.

著者

芦沢広三
宮崎大学農学部家畜病理学教室

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