A review of the literature: Tuberculosis among HTLV-1-infected individuals in Latin America

Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that predominantly targets CD4+ T lymphocytes and is transmitted via breastfeeding, sexual contact, and blood transfusions. Endemic regions of HTLV-1 infection often overlap with those of tuberculosis (TB). The mechanisms linking HTLV-1 to increased TB susceptibility remain unclear; it is hypothesized that the virus impairs T-cell function, which is crucial for immune defense against Mycobacterium TB, thereby influencing the clinical progression of TB. We conducted a literature review using the Medline, OVID, and Scielo databases, encompassing publications from January 2000 to July 2024. Eight studies involving 6901 participants from Latin America were included. They examined the relationship between HTLV-1 and TB, focusing on demographic, clinical, and mortality data. Coinfection rates varied across the studies, with HTLV-1-positive individuals showing a higher risk of developing TB compared to uninfected groups. TB symptoms were generally similar between HTLV-1-positive and seronegative patients. While one Peruvian study reported higher mortality rates in HTLV-1 co-infected patients, other analyses found no significant differences. Altered immune responses, such as changes in TNF-α and IL-17 levels, may contribute to the increased susceptibility to TB in individuals infected with HTLV-1. HTLV-1 should be considered during the diagnostic evaluation of TB cases in endemic regions. Given the under-recognition of HTLV-1, public health initiatives should emphasize the identification and management of coinfections. Further studies are necessary to clarify the immune mechanisms involved and generalize findings to other Latin American populations.