CASE PRESENTATIONS Patient 1 A 31-year-old bisexual man presented to the Johns Hopkins Hospital emergency department complaining of progressive headaches, confusion, myalgia, vivid nightmares, and diarrhea. For many years he had traveled extensively throughout sub-Saharan Africa and had recently spent 2 years in Madagascar. He had returned to the United States 1 month before admission. Once home, he developed diffuse myalgia and malaise. Stool analysis showed hookworm andEntamoeba histolytica, and he was treated with mebendazole and metronidazole 1 week before admission. During that week, he developed flulike symptoms of fever, chills, cough, and persistent diarrhea. Three days before admission, he developed a stiff neck, headaches, confusion, and vivid nightmares. His medical history included an inguinal hernia repair 12 years before admission and hepatitis A infection 7 years before admission. For the past 2 years, he had taken prophylactic chloroquine against malaria. Within the past 6 months, he had been