Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 21 2 2026 07 12 247 257 Yahya Azadeh Department of Medical Parasitology and Mycology, Cellular and Molecular Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran Shahram Khademvatan 1. Department of Medical Parasitology and Mycology, Cellular and Molecular Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran 2. Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Parkville, Victoria, 3010, Australia Zahra Goharfar Department of Periodontics, School of Dentistry Urmia University of Medical Sciences, Urmia, Iran Elham Yousfi ‎Department of Medical Parasitology and Mycology& Cellular and Molecular Research ‎Center, Cellular and Molecular Medicine Research Institute, Urmia University of ‎Medical Sciences, Urmia, Iran,‎ Shokoufeh Shahrabi-Farahani Department of Diagnostic Sciences, College of Dentistry, University of Tennessee, Knoxville, Tennessee USA Rasool Jafari Department of Medical Parasitology and Mycology, Cellular and Molecular Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran 2025 12 30 2026 07 12 Background: We aimed to determine the prevalence of Entamoeba gingivalis and Trichomonas tenax in relation to periodontitis in Urmia, Northwestern Iran, in 2022.  Methods: Gingival crevicular fluid (GCF) samples were collected from133 patients and analyzed using microscopic and molecular techniques to identify parasites. Data were analyzed using SPSS software and Chi-square and Fisher's exact test. Results: 42.1% of patients were infected with E. gingivalis and 11.3% with T. tenax. In comparison, microscopic diagnosis identified only 1.5% and 0.8% of patients infected, respectively. This highlights the increased sensitivity of molecular methods for parasite detection. A statistically significant relationship was observed between the presence of these parasites (identified by the molecular method) and several factors. Male patients had a significantly higher prevalence of E. gingivalis infection (P=0.037). Additionally, a history of diabetes (P=0.011) and cardiovascular diseases (P=0.021) was associated with a higher prevalence of E. gingivalis. The highest prevalence of E. gingivalis was observed in the 41–50-year age group (15 cases). Importantly, both E. gingivalis and T. tenax were significantly more prevalent in patients with severe periodontitis (P=0.003, P<0.001). Conclusion: This study demonstrates a higher prevalence of E. gingivalis compared to T. tenax in the oral cavity, suggesting its potentially greater role in periodontal disease, particularly among individuals with specific risk factors. Further research is warranted to elucidate the precise contribution of these parasites to periodontitis, identify additional risk factors, and develop improved diagnostic and treatment approaches. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/4862 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/4862/1499