High Sero Prevalence of the HIV-1, HIV-2 and HIV 1+2 Co- infection Among the HIV Patients Who Are on HIV- 1 ART Treatment Regimen in Njombe and Dares Salaam, Tanzania: Retrospective Cross‑sectional Study

<i>Background</i>: HIV-1 and HIV-2 have globally known HIV types with 55% genetic differences that resulted in the difference in ART treatment outcomes. HIV-1 is worldwide spread compared to HIV-2 dominated partly in Europe, the USA, and west Africa. Current studies have shown the spread of HIV-2 to other countries due to immigration and social economic activities interactions Objective, This study was aimed to determine the Seroprevalence of HIV-1, HIV-2, and HIV1+2 dual infection among the HIV patient on HIV -1 ART regimen treatment in Njombe and Dares salaam, Tanzania. Methods: A retrospective cross-sectional study was conducted from January 2020 to December 2021 at eight HIV Care and Treatment Centers. A total of 300 participants who were on HIV -1 ART regimen treatments from 2017 to 2019 were randomly selected and re-tested to determine HIV types SPSS version 26.0 was used for analysis whereby Percentages, Odds ratios (OR), 95% confidence intervals (CIs), and p-values of ≤0.001 were used for interpretation. Ethical clearance was sought from KNCHRE. All participants were provided with informed consent. Results: The mean age was 35.0 (SD ± 0.24) years. There was more female with HIV-1 110 (53.1%) compared to HIV-2 25 (56.8%) and dual infection. The general prevalence of HIV-1 was 69%, HIV- 2 was 15% and HIV-1+2 dual infections were 16%. In stratification by region, HIV-1 prevalence was high in Dares salaam 108(72%) compared to Njombe 99(66%) p=0.26 while the prevalence of HIV-2 was higher in Njombe 25(17%) compared to Dares Salaam 19(13%) p=0.33 and HIV 1+2 dual infection prevalence was high in Njombe 26(17%) compared in Dares -Salaam 23(15%) p=0.64. Conclusion: The study confirmed the presence of high prevalence of the HIV-2 and HIV 1+2 infections which were previously not found in Tanzania. Therefore, the urgent intervention on initiation of HIV-2 and HIV 1+2 dual infections ART regimen in Tanzania should be in place to reduce risks of poor clinical treatment outcomes of PLHIV with HIV-2 and HIV 1+2 infections.