BACKGROUND: Pathogenic blood-feeding nematodes, such as Haemonchus contortus and the invasive Ashworthius sidemi, infect a wide range of wild and domestic ruminants. While the spread of A. sidemi among European cervids has been studied, its presence in chamois (Rupicapra rupicapra) remains poorly documented. Conversely, H. contortus is known to infect chamois, but previous research has relied mainly on cross-sectional necropsy studies, offering only a limited view of infection dynamics. In this study, we used a longitudinal molecular approach to assess the seasonal occurrence and transmission patterns of H. contortus and A. sidemi in a chamois population from the northern Czech Republic. From January to December 2023, we collected faecal samples at monthly intervals from two localities. Multiplex real-time PCR was subsequently used for the detection and semi-quantification of DNA from both nematode species. RESULTS: Haemonchus contortus DNA was detected in 43.3% of samples, with its presence recorded nearly year-round. Its prevalence and relative DNA quantity peaked in summer and remained high throughout autumn. Ashworthius sidemi was identified in chamois in the Czech Republic for the first time, possibly reflecting a recent spillover from red deer (Cervus elaphus). However, it was found in only 5% of samples, with its occurrence restricted to late winter and spring. The seasonal disappearance of A. sidemi coincided with the increase in H. contortus relative DNA quantity, which may indicate a possible negative interaction between these species occupying the same ecological niche. CONCLUSION: Our findings suggest a potentialy prolonged transmission window for H. contortus, which could lengthen further under future climate change scenarios. In contrast, A. sidemi appears to be an incidental parasite in chamois, and its long-term persistence in this atypical host without continued contact with cervids remains uncertain. These insights, which are rare for wild ruminants, contribute to a better understanding of parasite epidemiology and host-parasite interactions in free-living populations.

• Keywords
• Ashworthius sidemi, Haemonchus contortus, Chamois, Epidemiology, Prevalence, Real-time PCR,
• MeSH
• Feces parasitology   MeSH
• Haemonchus * isolation & purification   genetics   MeSH
• Haemonchiasis * veterinary   epidemiology   parasitology   MeSH
• Seasons MeSH
• Rupicapra * parasitology   MeSH
• Abomasum parasitology   MeSH
• Trichostrongyloidea * isolation & purification   MeSH
• Trichostrongyloidiasis * veterinary   epidemiology   parasitology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic epidemiology   MeSH

Monitoring gastrointestinal helminth infections in wild ruminants poses significant challenges for managing wildlife health, particularly regarding invasive species. Traditional coprological methods are often limited by their labor-intensive nature and potential for erroneous identification due to morphological similarities among parasite species. This study employed advanced molecular techniques to assess the prevalence and distribution of several helminth taxa, including the invasive nematode Ashworthius sidemi and the trematode Fascioloides magna, in wild ruminant populations in the Czech Republic (CR). A comprehensive and extensive survey on parasite occurrence, unique in its nationwide scope, was conducted on 983 fecal samples collected from red deer (Cervus elaphus), roe deer (Capreolus capreolus), fallow deer (Dama dama), and mouflon (Ovis musimon) across various regions of the CR. The samples were analyzed using multiplex real-time PCR assays specifically designed to detect the DNA of six helminth representatives: the nematodes A. sidemi and Haemonchus spp., as well as the trematodes F. magna, Dicrocoelium dendriticum, Fasciola hepatica, and Calicophoron daubneyi (and representatives of the family Paramphistomidae, respectively). These assays targeted regions of ribosomal DNA (rDNA) and were designed to exhibit high sensitivity and specificity, enabling accurate detection of helminth parasites directly in fecal samples. The molecular assays revealed that invasive nematode A. sidemi was the most prevalent helminth species, detected in 15.8% of all samples (155/983), with the highest infection rate observed in red deer at 30.7% (124/404). Haemonchus spp. were also frequently detected, identified in 14.9% of samples (146/983), particularly in roe deer, with a prevalence of 23.2% (86/371). Spatial analysis of these nematodes across various regions of the CR revealed the extensive distribution of both A. sidemi and Haemonchus spp. in nearly all regions. In contrast, trematode infections were less common, with F. magna and D. dendriticum each found in only 1.5% of samples (15/983). Members of the family Paramphistomidae were detected in 0.2% of the samples (2/983) and were confirmed through sequencing as C. daubneyi. The geographical distribution patterns identified in this study indicate potential hotspots for specific helminth species. These findings are critical for planning health management and conservation strategies to mitigate the impacts of helminth infections, especially in areas affected by invasive species.

• Keywords
• Ashworthius sidemi, Fascioloides magna, Haemonchus spp., environmental fecal samples, multiplex real-time PCR, nested PCR, rumen flukes, wild ruminants,
• Publication type
• Journal Article MeSH