Review Question - QID 214726

A 24-year-old man presents to a rural emergency department in Arizona for weakness and a change in his behavior. The patient was hunting and drinking with his friends in the wilderness. While they were hiking through brush in the dark, the patient thinks he may have been bitten by something. For dinner, they ate commercially canned food and cooked meat over a campfire. Shortly thereafter, the patient complained of weakness, and his friends noticed he was abnormally drowsy and drooling. He has no significant past medical history and takes no medications. His temperature on presentation is 97.7°F (36.5°C), blood pressure is 114/74 mmHg, pulse is 81/min, respirations are 12/min, and oxygen saturation is 94% on room air. Physical exam is notable for a lethargic man who is drooling and requires repeated verbal prompting during the exam. The patient complains of double vision when testing visual acuity. His strength is 2/5 in his upper extremities and 4/5 in his lower extremities. Inspection of his lower extremities reveals 2 small parallel marks which have a small amount of blood surrounding them with absent swelling or oozing. Which of the following is the most likely etiology of this patient's symptoms?