宮崎県産イタチの肺虫感染について

概要

論文の詳細を見る
　宮崎県産イタチ36頭の肺を病理学的に検索した結果, うち3例に Filaroides martis と思われるものの集団寄生に基づく特異な結節病巣を検出した. 病巣の数は1頭につきそれぞれ3コ, 2コ, 1コであった. これらの結節型病巣は, いずれも肺内の太めの気管支(幹気管支･葉気管支及びその側枝のいずれか)とそれに平行して走る血管の管壁に密に接して位置する. 割面所見で数匹ないし数十匹の虫体が肺実質中に集団を成して寄生し, 寄生巣の外周は気管支･血管の管壁結合織の一部, 及び結節形成による周囲肺胞領域の圧迫により生じた幅狭い無気肺層で取り囲まれる. また集団寄生巣の内部には結合織が伸びて, 個々の虫体間に薄い隔壁を形成する.　ところで結節すなわち集団寄生巣内で成熟に達した虫体は, やがて寄生巣に接して位置する気管支系の管壁を突破し, 管腔の粘膜面に第1期子虫を放出する(すなわち本虫の発育環のスタートを切る). Stockdale et al. はイタチを用いての実験的観察により, F. martis は終宿主の血管(肺動脈枝)の外膜に沿うて肺内に進み, そこで気管支系との位置的関係を生じ, 最後に雌虫の尾部で気管支の粘膜を突破して子虫(第1期)を粘膜面に放出するのを確認した. 今回, れわれは自然例で気管支壁を突破中の虫体を認めたのは貴重なケースといえよう.　供試イタチの肺には結節型病巣を形成する F. martis 以外に, 細気管支腔及び肺胞領域に寄生する肺虫も認められた. 細気管支腔に寄生する虫体は F.martis に類似するが, 肺胞領域の虫体はすこぶる小型の線虫で虫種は不明. これら虫種不明のものも含めると, 供試イタチ36頭のうち肺虫の寄生を認めたのは11例で, かなり高い寄生率(30.6%)である. 従来, 本邦では F. martis は北海道産イタチにのみ報告されており, 九州産イタチとしては今回の事例が最初である.Nodular foci due to aggregative parasitism of Filaroides martis was observed in the lungs of 3 out 36 weasels (Mustela sibirica itatsi and M. sibirica coreana) captured in Miyazaki Prefecture. The number of nodular foci was one in the first case (median lobe of the right lung), three in the second case (median and posterior lobes of the right lung and posterior lobe of the left lung), and two in the third case (posterior lobes of right and left lung). The nodes were the size of a rice grain to soybean, and especially posterior lobe of the left lung in the third case, the size of the node relative to that of the pulmonary parenchyma was considerably large. Microscopically, these nodular foci were located closely adjacent to the large bronchi (stem bronchus or lobar bronchi and its branches) and the vascular walls running parallel to the bronchi. Several tens F. martis were parasitic in the nodes in aggregation, and these were surrounded by bronchial and vascular walls (connective tissue) and by a thin atelectatic layer which was formed by the compression of the alveolar area as the result of node formation. The connective tissue extended toward the inner part of the nodular focus, and an extremely thin septum was formed between adjacent parasites. The F. martis in the node (i. e., in the aggregative parasitic focus) that had attained sexual maturity broke through the bronchial wall that was adjacent to the parsitic focus, and discharged larvae onto the surface of the bronchial mucosa. This finding was confirmed by experimental observation by Stockdale et al., but confirmed for the first time under natural conditions in the present study. Besides the F. martis that produce nodiformic foci, lungworms parasitic in the lumen of the bronchiole and alveolar area were observed. The worm that was parasitic in the lumen of the bronchiole is similar to F. martis, but was not accurately identified. The parasite in the alveolar area was a very small nematode, but the species is unknown. Parasitism of lungworms including the above unknown species was observed in 11 of the 36 (30.6%) sampled weasels, which is a high rate. In Japan, F. martis was reported to have been detected only in weasels native of Hokkaido, and present study is the first time to report this parasite in weasels native of Kyushu.
宮崎大学農学部の論文

著者

芦沢広三
宮崎大学農学部家畜病理学教室

宮崎県産イタチの肺虫感染について

スポンサーリンク

概要

著者

関連論文

スポンサーリンク