The role of transmitter hosts of Echinococcus multilocularis in its present endemicity and the countermeasure against infectious source animals to humans

在北海道小清水和小樽对多房棘球蚴的天然最终宿主狐狸进行了驱虫试验。采用两种驱虫饵料：1)鱼粉香肠中加入驱虫吡喹酮片；2)机制含吡喹酮粉的水煮鱼膏。这些诱饵分布在狐狸繁殖巢穴周围，道路沿线或道路交叉路口和防风林。通过对狐狸粪便进行粪原抗原和卵检查和/或对研究区域捕获的狐狸进行尸检来评估狐狸种群中的流行情况。小清水和小丸饵饵分布区的狐狸流行率明显降低。札幌市市区狐狸繁殖窝周围发现粪原抗原和/或卵阳性狐狸粪便。由于红背田鼠在鼠穴附近被捕获，推测了多房田鼠可能的城市生活史。此外，通过对札幌及其郊区捕获的狐狸尸检结果与检测结果的比较，获得了粪原抗原检测法诊断的高可靠性。本研究表明了最终宿主在人类传播中的潜在作用，以及针对这些传播宿主的可行对策。在伴侣动物调查中，1997 - 2002年对北海道地区1650只狗和170只猫的粪便进行检测，共检出粪原抗原阳性18只和4只，检出卵阳性6只和6只。所有卵阳性犬共原抗原阳性。所有卵阳性的猫可能都感染了带绦虫。引人注目的是，2002年12月，在札幌的室内饲养犬中发现了第一例排卵病例。对除北海道以外地区64只狗和2只猫的粪便进行检测，发现2只粪原抗原和卵阳性狗。其中一只狗是从北海道搬来的。

Deworming trials to foxes, the natural definitive host of Echinococcus multilocularis, have been conducted in Koshimizu and Otaru, Hokkaido. Deworming baits used were 1) fishmeal sausage to which anthelmintic praziquantel tablet was put in and 2) machine-made boiled fish paste containing praziquantel powder. Those baits were distributed around fox breeding dens, along the road or at intersections of roads and windbreak forests. The prevalence in the fox population was evaluated by coproantigen and egg examination of fox feces and/or by autopsy of foxes captured at the study area. The prevalence of foxes in the bait distributed areas of Koshimizu and Otaru was significantly reduced.In Sapporo, coproantigen and/or egg positive fox feces were found around fox breeding dens lacated in urban area. Since red-backed voles were captured near the dens, possible urban life cycle of E. multilocularis was suggested. In addition, high reliability of the coproantigen detection method in diagnosis was obtained by the comparison of necropsy results of foxes captured in Sapporo and its suburbs and the test results.This study showed a potential role of the definitive hosts in transmission to humans, and a feasible countermeasure against those transmitter hosts.In the survey of companion animals, feces of 1,650 dogs and 170 cats in Hokkaido were tested during 1997 to 2002, and 18 and 4 coproantigen and 6 and 6 egg positive dogs and cats were found, respectively. All of the egg positive dogs were coproantigen positive. All of the egg positive cats were presumably infected with Taenia taeniaeformis. Strikingly, in Dec. 2002, the first egg excreting case was found among indoor keeping dogs in Sapporo. Feces of 64 dogs and 2 cats in the region other than Hokkaido were tested and 2 coproantigen and egg positive dogs were found. One of the dogs has moved from Hokkaido.