BackgroundBecause of shared modes of transmission, patients with hepatitis C virus (HCV) infection are often co-infected with other types of hepatitis viruses and/or HIV. We studied HCV viral load and its genotype patterns among HCV mono- and HCV/HIV co-infected Illicit Drug Users in Fars province-Iran.MethodsTotally, 580 HCV seropositive IDUs referred to Prof. Alborzi Clinical Microbiology Research Center, Shiraz, Iran, without receiving any anti-HCV treatment, were enrolled. After their HCV infections were reconfirmed by one step rapid diagnostic test, HCV RNA level and HCV genotypes were determined by Taq-man real-time PCR assays. Their HIV serostatus was determined and seropositive patients were excluded from the group.In addition, 104 HIV/HCV co-infected IDUs referred from Shiraz Behavioral Diseases Consultation Center (SBDC) were assessed for HCV RNA level and HCV genotype patterns, as well.ResultsThe overall estimated HIV prevalence was 6.7% (39/580) among HCV seropositive IDUs. Genotype 1, the most prevalent genotype in both groups, was detected in 69% and 49% of co- and mono-infected IDUs, respectively. Median HCV viral load was significantly higher in HIV/HCV co-infected patients, compared with that among HCV mono-infected counterparts.ConclusionsGiven the higher baseline HCV viral load and GT1 attributed to poorer treatments response, HCV treatment must be more considered among HCV/HIV co-infected IDUs, compared to those mono-infected with HCV.