A 60-year-old Japanese man presented to his primary care physician with a 2-week history of fevers, myalgias, fatigue, and sore throat. He was treated with amantadine and clarithromycin for 5 days without improvement. During this period, pain also developed in his right knee, and he sustained a 10-lb weight loss. There was no history of recent travel, contacts with sick individuals, or animal exposures. He was a nonsmoker, did not use illicit drugs, and drank socially. His other medications included metformin and rosuvastatin.