Gastrointestinal nematodes and coccidia in roe deer in years distinguished by summer heats

Parasites are the most common cause of disease in European roe deer (Capreolus capreolus), but prevalence of some invasions was smaller after a dry and hot summer. In the years 2015-2016, which were distinguished by exceptionally high temperature during summer months, the presence of nematodes and protozoa was assessed in the digestive tract of roe deer in western Poland. Studies confirmed that weather conditions may reduce gastrointestinal parasite prevalence in roe deer. In 2016, coccidiosis was not found in the examined species at all and in 2015 - it was rarely recorded. The reason for that could be the oocyst high exposure to sunlight as well as their drying as a consequence of high temperature and low precipitation. Such weather conditions also negatively affect other parasites when they are outside the host. Favourable environmental conditions for parasites probably occur more often in the forest than in the field, hence some gastrointestinal nematodes in the hot period were recorded only in roe deer in forest areas.