Taenia talicei in the Pampas foxes (Lycalopex gymnocercus) from Argentina: Molecular confirmation, prevalence, and host range.

Taenia talicei is the only Taenia species endemic to South America; however, its life cycle remains poorly understood. This study aimed to evaluate the role of the Pampas fox (Lycalopex gymnocercus) as a definitive host of T. talicei in Buenos Aires Province, Argentina, and to assess the tuco-tucos Ctenomys talarum and C. australis as intermediate hosts. Morphological examination of adult cestodes and metacestodes (including specimens from museum collections) was integrated with molecular analyses to confirm parasite identity and investigate host-parasite interactions. Prevalence was estimated and its association with capture area and host sex was evaluated, providing the first epidemiological data for this parasite in the region. Adult T. talicei were recovered from 19 of 106 foxes examined (17.9%; 95% CI: 11.2-26.6%), all from the Espinal ecoregion. Molecular analysis of seven specimens (five adult cestodes and two metacestodes) confirmed species identity in both host types. Spatial and dietary data support an active wild transmission cycle, with subterranean tuco-tucos serving as both intermediate hosts and prey. These findings expand the known host range of T. talicei and provide the first molecular confirmation of its wild transmission cycle, contributing new insights into its ecology and geographic distribution.