Parasitological community of red deer (Cervus elaphus): effects on population and reproduction

INTRODUCTION. Parasites are important indicators of biodiversity and biological parameter in wildlife as they can provide information about population health status, and about the potential interactions with other animal species and humans. Here we analyse parasite community in red deer to evauate (i) its effects on the species’ health status and, by focusing on adult females, (ii) its potential impacts on reproduction. Indeed, to our knowledge no studies are available on helminths-dependent abortion or reproductive disorders in wild ungulates. MATERIALS AND METHODS. A culling management plan within three macro-areas with different level of anthropization was conducted in Stelvio National Park in 2015, and faecal samples and abomasa were collected from 92 deer (47 adults including 32 females; 17 yearling and 28 calves). Parasitological investigations were performed in order to evaluate quantitatively parasite emission stages. Moreover, abomasal inspection and helminth morphological identification were carried out. Generalized Linear Models fitting kidney fat index (KFI), pregnancy and fetus weight as response variables and presence of pulmonar and abomasal helminths and emission of coccidia and helmintic eggs as predictors. RESULTS AND CONCLUSIONS. An overall prevalence of 59.8% and of 40.2% emerged for Eimeria spp. and helminthic eggs, respectively. Lung larvae had a prevalence of 80.4%. Abomasal inspection highlighted a prevalence of 29.3% showing Spiculopteragia spiculoptera, Tricostrongylus axei and Ostertagia leptospicularis (dominant species) and Rinadia mathevossiani (co-dominant species). Statistical analyses highlighted a significant negative effect of lung larvae on KFI. None of the variables influenced the pregnancy probability, but fetus weight was significantly affected by abomasal abundance. Weight of fetus had average values of 438 g in negative females, 314 g with abomasal charge up to 40 helminths and 98 g when helminths was >40. Pulmonar parasites showed an impact on red deer health although larvae species require species indentification to discriminate their patogenicity. Conversely the recorded gastro-intestinal helmints did not affect animals. However, although parasites had no impact on pregnancy, abomasal intensity showed an indirect negative effect on fetus development. This result would suggest that helminths may influence the reproductive potential of red deer.