A 27-year-old man without any significant past medical history presented to the emergency room in Boston with 1 week of intermittent fever, headaches, and nonproductive cough and 1day of dyspnea. He had quit tobacco smoking 6 months prior but vaped nicotine and kratom regularly. He did not have any recent international travel. He often swam in freshwater ponds for recreation. He noted occasional rats at home. On presentation, his temperature was 101.4 °F; blood pressure, 126/72mm Hg; heart rate, 100 beats/min; respiratory rate, 26/min; and oxygen saturation (SpO2), 92% on room air.