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

在北海道的小清水和小樽，对多房棘球绦虫的自然终末宿主狐狸进行了驱虫试验。所用的驱虫饵为1）放入驱虫吡喹酮片剂的鱼粉香肠和2）含有吡喹酮粉的机制煮鱼膏。这些诱饵分布在狐狸繁殖窝点周围、沿着或道路与防风林的交叉口。通过对狐狸粪便进行粪抗原和卵检查和/或对在研究区域捕获的狐狸进行尸检，评价狐狸种群中的患病率。小清水和小樽的狐饵分布区狐的流行率明显降低，札幌市区狐饵分布区狐粪抗原和/或卵阳性。由于在巢穴附近捕获了红背田鼠，因此E.多房性。此外，通过比较在札幌及其郊区捕获的狐狸的尸检结果和试验结果，证明粪抗原检测方法在诊断中具有很高的可靠性。本研究显示了终末宿主在传播给人类中的潜在作用，以及针对这些传播宿主的可行对策。1997 ~ 2002年对北海道的650只犬和170只猫进行了粪抗原检测，分别检出粪抗原阳性18只和粪抗原阳性4只，虫卵阳性6只和虫卵阳性6只。所有虫卵阳性犬粪抗原阳性。所有虫卵阳性的猫都可能感染了带绦虫。引人注目的是，2002年12月，在札幌的室内饲养的狗中发现了第一例排蛋病例。对北海道以外地区的64只狗和2只猫的粪便进行了检测，发现2只粪抗原和虫卵阳性的狗，其中1只狗是从北海道迁来的。

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.