Introduction and objective:
Data concerning the occurrence of intestinal parasites among the Polish population remain limited. The aim of the study is to assess the carriage of intestinal parasites among adults from north-eastern Poland and to identify demographic and clinical factors associated with their detection.

Material and methods:
A cross-sectional study was conducted among 118 adults from the Podlaskie Province in north-eastern Poland. Stool samples were examined microscopically for the presence of intestinal parasites and other intestinal eukaryotic organisms. In addition, molecular assays targetting selected clinically relevant intestinal parasites were performed. Demographic characteristics and gastrointestinal symptoms were collected using a structured questionnaire. Associations between organism detection and demographic or clinical variables were assessed statistically.

Results:
Intestinal organisms were detected in 20/118 participants (16.9%), including 19 (16.1%) harbouring pathogenic or potentially pathogenic species. The most frequently identified organisms were Blastocystis spp. (n = 13) and Dientamoeba fragilis (n = 5). Single cases of Giardia intestinalis, Enterobius vermicularis, Entamoeba coli, and Endolimax nana were observed. Increasing age was significantly associated with the presence of intestinal organisms (p = 0.016).

Conclusions:
The prevalence of intestinal parasites among adults in north-eastern Poland was low and was largely driven by the detection of Blastocystis spp. and Dientamoeba fragilis. Pathogenic parasites were rare, whereas older age was associated with a higher likelihood of intestinal organism detection. Intestinal parasites, particularly Blastocystis spp. and intestinal protists, remain an important component of adult gut ecology and epidemiology despite the low burden of clinically significant parasitic infections.