Diversity of Helminth Parasites in the Fat Sand Rat, Psammomys obesus Cretzschmar, 1828, from Tunisia

Psammomys obesus is a diurnal herbivorous rodent widely distributed across the arid regions of North Africa and the Arabian Peninsula. Although it has ecological, agricultural, public health, and biomedical importance, its helminth fauna remains poorly known. This study provides a comprehensive inventory of helminth parasites infecting P. obesus in southern Tunisia and examines variations in parasitism according to host sex, age, body condition, and sampling region. A total of 152 specimens of P. obesus were captured between September 2023 and March 2026 in the Tamaghza and Djebel Dahar regions. Parasitological examination revealed four helminth species: three cestodes, Gerbillitaenia psammomi, Sudarikovina aegyptica, and Mesocestoides sp. larvae, and one nematode, Syphacia sp. Their respective prevalences were 63.8%, 12.5%, 0.7%, and 16.4%. The species are morphologically described, and genetic data and a phylogenetic tree are provided for Syphacia sp. The findings of Mesocestoides and Syphacia species represent new records for P. obesus. Furthermore, S. aegyptica constitutes a new record for Tunisia. Host age and sampling region significantly influenced the occurrence and abundance of G. psammomi, as adults were more likely to be infected and harbored a significantly higher parasite burden than juveniles. In contrast, neither host sex nor body condition was significantly associated with parasite occurrence or abundance. No significant association between parasite occurrence or abundance and the host’s sex, age, or body condition was found for S. aegyptica and Syphacia sp.