Infections with Human T-cell Lymphotropic Virus types 1 and 2 (HTLV1/2) are common among HIV-positive people who inject drugs (PWIDs). There is scarcity of information on HIV/HTLV-1/2 co-infection among PWIDs.Co-infection is prevalent since the three viruses have comparable transmission pathways and T-lymphocyte tropism. Since HTLV-1 induces an increase in viral replication, HIV infection is worsened as the course to Acquired Immune Deficiency Syndrome (AIDS) is hastened. Between 2016 and 2017, this study sought to determine the prevalence of HIV and HTLV-1/2 co-infection among PWIDs in Malindi Sub County in Kenya. This was a cross-sectional study involving 351 consenting PWIDs. A structured questionnaire was used to collect socio-demographic and behavioral data, followed by laboratory examination of blood samples. HIV-1 and HTLV-1/2 screening was done using VironostikaHIVAg/Ab protocol and HTLV1/2 Enzyme-linked Immunosorbent Assay (ELISA) respectively. Of the 351 PWIDs recruited (mean age 33.1years, SD= ± 6.5), 9.7% (34/351) were positive for HIV, 5.8% (20/351) were positive for HTLV1/2 while 0.9% (3/34) were HIV/ HTLV co-infected. Significant risk factors for HIV infection included homelessness (OR=2.5(1.3-5.3), p=0.009), sharing of needles (OR=2.1(1.0-4.3), p=0.042) and previous history of gonorrhea and syphilis (OR=3.7(1.9-7.5), p<0.0005). Unprotected anal sex (OR=3.1(1.1-8.5), p=0.029), living in Malindi (OR=7.9(1.1-59.6), p=0.043) and a previous record of gonorrhea and syphilis infections (OR=2.9(1.2-7.3), p=0.021) were all linked to HTLV-1/2 infection. Our study indicates that needle sharing and sexual promiscuity increase the risk of acquiring these infections. Routine testing of HIV and HTLV1/2 should be considered in all outpatient PWIDs clinics. This will provide data on prevalence and inform policies which will help mitigate further transmission of these viruses.

Keywords: PWIDs, HIV, HTLV, Risk factors, Co-infection, Prevalence, Malindi