The common vole, Microtus arvalis Pall. as intermediate host of Mesocestoides (Cestoda) in Germany.

Tetrathyridia of Mesocestoides leptothylacus Loos-Frank, 1980 were found in 1.4% of 513 common voles (Microtus arvalis) in a district of Southwest Germany where foxes (Vulpes vulpes) are frequently infected with this tapeworm. The tetrathyridia measured 1 to 1.5 mm in length and 0.5 to 1 mm in width. When injected intraperitoneally into white mice, jirds, or common voles, the tetrathyridia did not multiply. Cats fed with the larvae shed proglottids from the 21st day onwards. In one experimentally infected silver-fox proglottids were passed from day 12 onwards. One human subject infected twice with tetrathyridia of M. leptothylacus, did not develop patent infections. One common vole from another district contained tetrathyridia of a Mesocestoides species, which is rarely found in indigenous foxes and which is characterized by a broad-oval cirrus pouch with a much convoluted cirrus.