Naegleria fowleri (Primary amebic meningoencephalitis)

A 30-year-old woman is brought to the emergency department by her partner due to high fever and severe headache accompanied by nausea and vomiting. The partner reported that the patient was fine until 2 days ago, when she started complaining of a headache and rapidly became confused. Temperature is 38.9°C (102°F), pulse is 80/min, respirations are 20/min, and blood pressure is 135/85 mmHg. On physical examination, the patient is obtunded and responds only to noxious stimuli. Pupils are equal and responsive to light. When the neck is flexed, the patient flexes the lower limbs. A thorough skin examination reveals no rashes, petechiae, or purpura. CSF analysis shows elevated WBC count with polymorphonuclear predominance, low glucose, high protein, and numerous RBCs. A wet mount is performed and reveals the following:  


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Further review of this patient's history will most likely reveal which of the following?