HIV/HTLV-1 co-infection: a systematic review of current evidence

Human T-cell leukemia/lymphoma virus type 1 (HTLV-1) infection is associated with myelopathy/ tropical spastic paraparesis (HAM/TSP) and adult T cell leukemia/lymphoma (ATLL), which is a malignancy of mature T lymphocytes. HTLV-2 pathogenesis for humans remains undefined. As they share the same transmission routes, co-infection with human immunodeficiency virus (HIV) and HTLV-1 are often reported among the world, mainly among patients living in highly endemic areas like South America and sub-Saharan Africa. Nevertheless, many clinicians are not aware of the potential risks of co-infection with HTLV-1 when treating an HIV patient. Since both viruses infect CD4+ T lymphocytes, scientists have investigated interactions at the cellular and molecular levels, clinical associations, and related complications. Studies have shown that co-infection with HTLV-1 resulted in an increased CD4+ T lymphocyte count, which might be mistaken for immune compatibility, and lead to a delay in the establishment of antiretroviral therapy (ART) in HIV-positive patients. Some authors have observed that co-infection with HTLV-1/HIV-1 can lead to an acceleration of AIDS progression and lessening survival times. Even so, conflicting results and controversies have been reported. These conflicts high-light the requirement of further studies to provide valuable information within this area. In this systematic review, we summarize the current evidence on the co-infection with HTLV-1 among HIV-positive patients, its associated complications, and the impact on progression of AIDS.