Abstract
Blastocystis is one of the most common protists colonizing the gastrointestinal tract of humans and animals worldwide. The aim of this study was to analyze the occurrence of Blastocystis in wild roe deer (Capreolus capreolus) from Central Poland, as well as to determine its zoonotic potential and the influence of selected environmental factors on the infection level. A total of 151 fecal samples were collected and analyzed using PCR amplification followed by DNA sequencing. To identify predictors of Blastocystis occurrence, data on animal characteristics, season, and landscape structure were compiled. Variables were analyzed using a binary generalized linear model with AIC selection. Blastocystis was detected in 49 samples (32.5%). Sequence analysis revealed three subtypes: ST14 (53.1%), ST13 (32.7%), and ST10 (10.2%), while two samples (4.0%) remained classified at the genus level. Roe deer present on wind farms (p = 0.016) and in areas with a higher percentage of settlements (p = 0.035) had a significantly lower probability of colonization. Conversely, the probability of Blastocystis presence increased with a higher proportion of arable land (p = 0.012) and surface water (p = 0.024). Although a zoonotic risk exists, its potential in the studied population appears to be low. The transmission risk may be influenced by factors related to landscape structure and anthropogenic pressure.