Co-occurrence of metacestodes of Echinococcus multilocularis and Taenia taeniaeformis (Cestoda) in Arvicola terrestris (Rodentia) in France.

In western Europe, the natural life cycle of Echinococcus multilocularis (Leuckart, 1863) involves mostly foxes, dogs and cats as definitive hosts and voles (Arvicolidae) as intermediate hosts. Studies on this topic are often restricted to data on prevalence of this tapeworm. However, until now, an association of E. multilocularis with larvae of another cestode species has only been reported from Rattus norvegicus in Japan (Okamoto M., Fujita O., Arikawa J., Kurosawa T., Oku Y., Kamiya M. 1992: Int. J. Parasitol. 22: 681–684). This paper reports our results of necropsy of 1807 voles belonging to 3 species, Arvicola terrestris (Linnaeus), Microtus arvalis (Pallas), Clethrionomys glareolus (Schreber) and 22 Apodemus sylvaticus (Linnaeus) (Table 1) trapped in a mountainous region of Central France between 1980 and 1990 and in 1995. They were captured alive, killed under anaesthesia and dissected. The livers were examined macroscopically for the presence of metacestodes of E. multilocularis and other cestode larval stages. Livers without macroscopical metacestodes were sectioned by hand (the thickness of sections: 1.5 mm) and observed under the dissecting microscope. All liver metacestodes were fixed in a 5% neutral formaldehyde solution. Echinococcus multilocularis metacestodes were studied by traditional histological methods. Other metacestodes were cleared or examined histologically for the presence of the hooks. The species determination of the Taeniidae was performed according to Abuladze (Abuladze K.I. 1964: Taeniata of Animals and Man and Diseases Caused by Them. Essentials of Cestodology IV. Nauka, Moscow, 530 pp.), Verster (Verster A. 1969: Onderstepoort J. Vet. Res. 36: 3–58) and Loos-Frank (Loos-Frank B. 2000: Syst. Parasitol. 45: 155–183). The species of rodents and the number of rodents infected by E. multilocularis are shown in Table 1. Larval stages of other cestodes found in voles and A. sylvaticus are summa-