A 30-year-old man presents to the emergency department with a 2-week history of cervical lymphadenopathy, drenching night sweats, and unintentional weight loss of 15 lb. A CT scan shows diffuse, bulky lymphadenopathy in the neck, mediastinum, retroperitoneum, and iliac lymph nodes. Laboratory results reveal a blood urea nitrogen level of 56 mg/dL, serum creatinine level of 2.5 mg/dL, calcium level of 13 mg/dL, and a lactate dehydrogenase level 4 times the upper limit of normal. His complete blood count is normal except for a leukocyte count of 24.6 ×103/µL with 70% lymphocytes, some of which are atypical in appearance. He is originally from Jamaica and has no significant past medical history. He has had multiple female sexual partners but has never used intravenous drugs. Which virus is the most likely cause of this patient’s illness?
Human T-lymphotrophic virus type 1 (HTLV-1)