What is HTLV-1 virus? What is its significance?

HTLV-1 is a type C retrovirus associated with T-cell lymphoma and leukemia. It was initially isolated from a patient diagnosed with mycosis fungoides. The virus is endemic in Japan, the Caribbean, and northeastern South America; a few cases have been reported in the United States. It can be transmitted by blood transfusions, intravenous drug abuse, breast feeding, and, less commonly, sexual contact. A small subset of patients who are HTLV-1–antibody positive (<5%) will develop lymphoma or lymphocytic leukemia. The disease is characterized by immunosuppression, lymphadenopathy, cutaneous lesions, and hypercalcemia.