Sabry, DinaShaker, Marwa AbdallahHassouna, AmiraElRefai, SaharDiaa, NehalSaad, Ghada ATawfeik, Amany MAnani, Haneya AAAttia, Abdelrahman MAli, Asmaa RashadEl-makromy, Gena MShams El-Din, Hala E2026-06-112026-06-112026-01-05The Microbe, ISSN: 2950-1946 (Print), Elsevier BV, 10, 100657-100657. doi: 10.1016/j.microb.2026.1006572950-1946http://hdl.handle.net/10292/21377An imbalance in the oral microbiota, known as oral dysbiosis, can lead to periodontitis. Hepatitis C virus (HCV) infections may impact oral health through immune function, diet, and lifestyle alterations, potentially contributing to periodontal disease development. The role of Protozoa in oral dysbiosis is still poorly understood. The contribution of oral Protozoa as Entamoeba gingivalis and Trichomonas tenax in periodontitis in HCV-infected patients has not been adequately invetigated. This research explored their prevalence and association with periodontitis in HCV-infected patients compared to healthy individuals without periodontitis (infected control). Venous blood samples were drawn to measure serum ALT, AST, albumin, urea, creatinine, iron, ferritin, transferrin, and sTfR. Serum and saliva samples were used to measure HCV RNA and detect the oral parasites Entamoeba gingivalis and Trichomonas tenax using polymerase chain reaction (PCR). A total of 242 participants were enrolled in the study, divided into the following groups: HCV patients with periodontitis (n = 73), HCV patients without periodontitis (n = 47), and healthy subjects (n = 122). AST, ALT, and urea were significantly elevated in HCV-infected patients compared to the control group(p < 0.05). However, no significant differences were observed in albumin and creatinine levels between the two groups (p > 0.05). Iron-related parameters were significantly lower in HCV-infected patients compared to the control groups(p < 0.05). The prevalence of T. tenax and E. gingivalis among the HCV patients with periodontitis was 34.2 % (n = 25) and 49.3 % (n = 36), respectively, with a high statistically significant difference compared to the control groups (p < 0.001). While T. tenax positivity only demonstrated a statistically significant positive correlation with HCV copy number in saliva (p < 0.05)., E. gingivalis positivity was significantly correlated with HCV copy number in both serum and saliva samples(p < 0.05). Following HCV treatment, the prevalence of E. gingivalis and T. tenax decreased significantly, from 49.3 % and 34.2–11.0 % and 6.8 %, respectively (p < 0.001). The results showed that HCV patients with periodontitis had a considerably higher prevalence of E. gingivalis and T. tenax, which significantly decreased after HCV treatment. Therefore, the conventional perception of E. gingivalis and T. tenax as harmless symbionts warrants reassessment, as their role in the pathophysiology of periodontal diseases cannot be disregarded.© 2026 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)http://creativecommons.org/licenses/by/4.0/32 Biomedical and Clinical Sciences3203 DentistryDental/Oral and Craniofacial DiseaseHepatitis - CMinority HealthChronic Liver Disease and CirrhosisMicrobiomeHealth Disparities and Racial or Ethnic Minority Health ResearchLiver DiseaseInfectious DiseasesClinical ResearchDigestive DiseasesHepatitisEmerging Infectious Diseases2.1 Biological and endogenous factorsInfection3 Good Health and Well BeingJournal ArticleOpenAccess10.1016/j.microb.2026.100657