Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 18 3 2026 06 07 382 392 EN Azadeh Haghi Navand Cellular and Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; Department of Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Azarakhsh Azaran Department of Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Mina Bavi Department of Virology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Farid Yousefi Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Maryam Dastorpour Department of Biostatistics and Epidemiology, School of Public Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Manoochehr Makvandi Cellular and Molecular Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran 2024 07 25 2026 05 27 Background and Objectives: Routine screening for occult hepatitis C virus (OHCV) is not a standard procedure in medical laboratories, which has resulted in an increased incidence of OHCV among high-risk groups and the general population. The objective of this study was to investigate the molecular epidemiology of (OHCV) in Iranian injecting drug users (IDUs). Materials and Methods: To determine chronic hepatitis C virus(HCV) and OHCV, plasma and peripheral blood mononuclear cell (PBMC) were collected from 103 (96 (93.2%) males, 7 (6.79%) females) IDUs. Their plasma was tested for Anti-HCV (ELISA). Following RNA extraction from plasma and PBMCs, RT-nested PCR was employed to amplify the 5′ untranslated region (5′UTR) and core regions of the HCV genome in plasma and PBMCs from IDUs. Sequencing of the 5′UTR and core regions, along with phylogenetic tree construction, was used to determine HCV genotypes. Results: Among the 103 individuals, 12/96 males (12.5%) were positive for both anti-HCV and HCV RNA in plasma, indicating chronic HCV infection. In addition, 18/96 males (18.75%) and 1/7 females (14.28%) were positive for anti-HCV but negative for HCV RNA, indicating evidence of past HCV infection (p = 0.1). Furthermore, 5 individuals, including 4/94 males (4.1%) and 1/7 females (14.28%), were found to be seropositive for HCV (p = 0.77). Meanwhile, 23/103 individuals (22.33%), including 20/96 males (20.8%) and 3/7 females (42.85%), were seronegative for HCV (p = 0.37). HCV genotype 1a was the dominant genotype among IDUs. Conclusion: In conclusion, a high prevalence of HCV infection was observed among IDUs, underscoring the pressing necessity for the implementation of an efficacious strategy to eradicate HCV transmission in this high-risk population. https://ijm.tums.ac.ir/index.php/ijm/article/view/4939 https://ijm.tums.ac.ir/index.php/ijm/article/download/4939/1898