HTLV, or Human T-Cell Lymphotropic Virus, is a group of viruses that can infect human T-cells, a type of white blood cell important for the immune system. There are several types of HTLV, with HTLV-1 and HTLV-2 being the most studied. HTLV-1 is associated with certain diseases, including a type of cancer called adult T-cell leukemia/lymphoma and HTLV-associated myelopathy. Transmission of HTLV occurs through contact with infected bodily fluids, such as blood, breast milk, and sexual fluids. It is more prevalent in specific regions, including parts of Japan, Africa, and South America. While many people infected with HTLV may not show symptoms, regular monitoring is important for those at risk.