Environmental effects on the lung and gastrointestinal parasite fauna of wild boar: a comparative study between alpine and Mediterranean ecosystems

Purpose: This study aims to explore environmental factors associated with parasite infections in faecal samples collected from wild boar populations, by analysing the prevalence, intensity, and abundance of parasite communities across two Italian ecosystems: the alpine environment in the Orco Valley (Gran Paradiso National Park) and the Mediterranean lowland in the Maremma Regional Park. Methods: Seasonal faecal samples were collected from November 2023 to July 2025 along systematic transects in both study areas. Samples were analysed using the Mini-FLOTAC technique to quantify parasite eggs and (oo)cysts, and prevalence, intensity, and abundance were calculated. Environmental variables, including elevation, land use, temperature, precipitation, and season, were linked to each sample. Generalized linear models (GLMs) were fitted to evaluate the effects of environmental factors on parasite presence and abundance. Results: Parasite communities were dominated by Eimeria spp., gastrointestinal strongyles, and Metastrongylus spp., whereas other taxa (e.g., Balantioides coli, Capillaria spp., Cystoisospora sp.) were sporadic. Significant differences in intensity and/or abundance of dominant taxa were observed between the two areas. Models based on infection abundance, rather than presence, revealed environmental associations: Metastrongylus spp. abundance decreased with increasing elevation, possibly reflecting constraints on intermediate host availability; while gastrointestinal strongyles abundance was lower in open natural habitats, reflecting microclimatic influences on larval survival. Conclusions: This study highlights associations between habitat characteristics and parasite community structure in wild boar populations, providing insights into the environmental factors potentially influencing parasite transmission across heterogeneous landscapes.