Background and study aim: The Oral cavity harbors many microorganisms and their balance is essential for its ‎health. Entamoeba gingivalis and Trichomonas tenax are the most commonly ‎found oral protozoa. This study aims to explore their prevalence in patients with ‎chronic systemic diseases and the associated risk factors.‎‎‎‎.
Materials and Methods: This case-control study included 150 chronic patients from Fayoum Governorate, ‎Egypt, designated into three groups (50 each). These are; a group of diabetic ‎patients, a group of chronic renal failure on regular hemodialysis, and a group of ‎chronic liver diseases with Child-Pugh Class B and C. In addition to 50 healthy ‎volunteer subjects were enrolled as a control group. A specialized dentist collected ‎dental plaques and saliva samples from all subjects. A designed questionnaire was ‎taken for personal, demographic data, oral risk factors as regular oral hygiene, ‎smoking, halitosis, and history of chronic or recurrent gum and teeth complaints‎. Oral samples were examined using direct microscopy, saline wet mount, and ‎Giemsa staining.  Each sample was cultured on Diamond's medium [TYM] for ‎detection of T. tenax, and on Locke's-egg medium for detection of E. gingivalis. ‎HbA1c as indicator for diabetic control was measured in sera drawn from cases and controls.‎
Results: The prevalence of oral protozoa was significantly increased in chronic diseases, ‎as E. gingivalis was reported in 80%, 76, and 74% of diabetic, renal, and hepatic ‎groups of patients respectively compared to 20% in the control healthy group. ‎While T. tenax was reported in 70%, 62%, and 64% respectively compared to 16 ‎‎% in the control group < em>‎‎‎‎‎‎‎‎‎.
Conclusion: This high prevalence in chronic systemic disease needs more investigations ‎concerning its pathogenesis, immunological mediators that may affect systemic ‎diseases and the interplay between them‎ ‎‎‎‎‎‎‎.