Work

Seasonal occurrence of gastrointestinal helminths in a feral horse population from a Mediterranean mountain ecosystem

Year: 2026

Type: article

Abstract: Mediterranean mountain ecosystems are characterized by strong seasonal climatic variation and environmental constraints that may substantially influence parasite transmission dynamics in free-ranging herbivores. However, little information is available regarding gastrointestinal parasite circulation in unmanaged equids inhabiting alpine grazing systems. This study investigated the seasonal dynamics of gastrointestinal helminths and the occurrence of Strongylus vulgaris in a feral horse population inhabiting the Sierra Nevada Natural Space (southern Spain), the southernmost alpine ecosystem in Europe. Faecal samples were collected across four seasons and analysed using quantitative coprological and molecular methods. Strongylid eggs were detected in almost all examined horses throughout the study period, indicating sustained parasite circulation under free-ranging conditions and in the absence of anthelmintic intervention. Although generalized linear mixed models did not detect statistically significant seasonal differences in egg shedding intensity, the highest egg counts were recorded during summer, coinciding with the period of maximum use of alpine grazing areas. Molecular analyses revealed a consistently high prevalence of S. vulgaris across seasons, whereas Parascaris spp . and Anoplocephala spp . were only sporadically detected. The predominance and persistence of strongylids likely reflect the ecological advantages conferred by direct transmission cycles in Mediterranean mountain grazing systems. These findings provide novel insights into parasite ecology in unmanaged equids inhabiting high-altitude ecosystems and highlight the value of feral horse populations as natural models for investigating host–parasite interactions under changing mountain environmental conditions.

Source: Scientific Reports

DOI: 10.1038/s41598-026-69065-6