system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 28-year-old man presents to the physician because of dizziness and palpitations for the past 12 hours and fever, malaise, headache, and myalgias for the past week. The patient traveled into the woods of Massachusetts 4 weeks ago. He has no known chronic medical conditions, and there is no history of substance use. His temperature is 38.3°C (100.9°F), pulse is 52/min, respirations are 16/min, and blood pressure is 126/84 mm Hg. His physical examination shows a single, 10-cm, round, erythematous lesion with a bull’s-eye pattern in the right popliteal fossa. His electrocardiogram shows Mobitz I second-degree atrioventricular (AV) block. The complete blood cell count and serum electrolyte levels are normal, but the erythrocyte sedimentation rate is 35 mm/hour. What is the most likely cause of the patient’s cardiac symptoms?
assistant
 Spirochete infection