Prevalence of Human Immunodeficiency Virus and Hepatitis C Virus Co-Infection Among Injection Drug Users in Lagos State

HIV and hepatitis C virus (HCV) co-infection among injection drug users (IDUs) presents complex treatment and public health management challenges, and Nigeria's IDU population in Lagos State represents an under-studied high-risk group for dual transmission. This study determines the prevalence of HIV-HCV co-infection and associated risk factors among injection drug users in Lagos State, South West Nigeria. A community-based cross-sectional study recruited 150 active IDUs through peer-based outreach in Agege and Mushin using respondent-driven sampling. Blood samples were collected for HIV antibody testing by rapid test and ELISA, and HCV antibody detection by third-generation ELISA, with RNA confirmation of HCV-positive samples by PCR. A structured risk behaviour questionnaire was administered. HIV prevalence was 32 percent, HCV prevalence was 48 percent, and HIV-HCV co-infection was found in 22 percent of participants. Needle sharing (OR 5.8), injecting for over five years (OR 4.2), and sex work co-engagement (OR 3.1) were significant co-infection predictors. HCV genotype 1 and genotype 4 were the dominant circulating strains. Only 15 percent of HIV-positive IDUs were aware of their status before recruitment. The study calls for integrated harm reduction, HIV testing, and HCV screening services for Lagos IDU populations, with linkage to direct-acting antiviral HCV treatment pathways. Keywords: HIV, Hepatitis C, co-infection, injection drug users, Lagos State