Ann, a healthy 37-year-old biology teacher had just returned from Japan, where she was attending a two-week seminar. On the plane trip back to the U.S., Ann began to experience chills, fever, and a severe headache. The day after she arrived home, she visited her doctor. After noticing some abnormal reflex responses, he admitted her to the hospital and obtained a sample of cerebrospinal fluid by spinal tap. He ordered penicillin therapy intravenously and Tylenol for discomfort.