Pinworm infections in red squirrels at the urban-forest interface

The growing overlap between urban and forest environments increases the risk of cross-species parasite transmission, making the study of parasitic fauna in wild mammals highly relevant. The aim of this research was to investigate the prevalence and host specificity of oxyurid nematodes in Eurasian red squirrels (Sciurus vulgaris) inhabiting forested park areas of Polissia, Ukraine. It was analysed 191 faecal samples collected between September and December 2023 using an integrated approach that combined innovative monitoring methods, including video surveillance in the squirrels’ natural habitat, systematic sample collection, and detailed microscopic examination of helminth egg morphology. Additionally, the YOLOv5 computer vision model was utilized for automated analysis of video recordings, enabling precise identification of individual squirrels. Three species of parasites from the superfamily Oxyuroidea were identified in this study. The squirrel-specific species Trypanoxyuris sciuri was the most prevalent, detected in 70.6% of squirrels (12 out of 17 individuals; 95% CI: 44.04-89.69). Parasites typically associated with murids were less common: Syphacia obvelata was found in 11.8% of squirrels (2 out of 17; 95% CI: 1.46-36.44), and Aspiculuris dinniki in 5.9% (1 out of 17; 95% CI: 0.15-28.69). To further investigate these species, S. obvelata eggs were cultured under laboratory conditions, allowing for detailed characterization of L1 larvae morphology, while A. dinniki failed to develop, confirming its specific host requirements. These findings highlighted the high prevalence of T. sciuri among squirrels and indicated the potential transmission of S. obvelata and A. dinniki within their populations. The practical value of this study lies in expanding the understanding of helminth diversity and host-parasite interactions in transitional urban-forest ecosystems. The obtained results can be used to improve veterinary and sanitary measures, prevent parasitic diseases, and develop monitoring strategies aimed at preserving the health of wild populations and minimising risks to domestic animals and humans