HTLV-I, or Human T-cell Lymphotropic Virus Type I, is a retrovirus that primarily infects T-cells, a type of white blood cell crucial for the immune system. It is transmitted through bodily fluids, including blood, breast milk, and sexual contact. HTLV-I is associated with several health conditions, including Adult T-cell Leukemia and HTLV-I-associated Myelopathy. The virus is prevalent in certain regions, particularly in Japan, Caribbean countries, and parts of Africa. Many individuals infected with HTLV-I may remain asymptomatic for years, but some can develop serious health issues later in life. There is currently no cure for HTLV-I, making prevention and early detection important.