Cultivation of a wild type Taenia crassiceps isolate from a zoo-kept Lemur and its application in anthelmintic drug testing

Taenia crassiceps, a cestode cycling between canids and rodents, poses a significant threat to zoo-kept primates, which are highly susceptible to severe cysticercosis. Fenbendazole is commonly used for treatment, though efficacy varies with lesion severity and localization of the disease-causing metacestode. In this study, T. crassiceps metacestodes, molecularly confirmed, were obtained from skin lesions collected from a Lemur catta that died at Zoo Salzburg. Parasites were cultured and treated with standard anthelmintics - albendazole, fenbendazole, mebendazole, and praziquantel - at 40 μM to evaluate in vitro efficacy. Young (1-week) and old (17-week) cultures were used to asses drug efficacy by damage-marker release assay measuring the release of phosphoglucose isomerase (PGI) after 5 and 12 days. An automated assay measured motility reduction. Both drug testing methods were adapted from a well-established in vitro system for Echinococcus, enabling future cross-species comparisons. Praziquantel showed the most pronounced effect on parasite integrity after 12 days (29 % PGI release versus detergent control) and completely halted motility. Benzimidazoles were less effective when tested at same concentrations. Albendazole and mebendazole showed moderate PGI release (14 %), while fenbendazole showed none. Among benzimidazoles, mebendazole reduced motility most (49 %), followed by albendazole (56 %) and fenbendazole (87 %). We successfully adapted in vitro screening methods for T. crassiceps metacestodes using established techniques for Echinococcus. Although not aimed at identifying alternative treatments, findings suggest praziquantel - alone or with mebendazole - may offer more effective management for T. crassiceps in zoo primates than fenbendazole alone until better therapies become available.