Neurocysticercosis—a disease in which a young tapeworm infects the brain—is common in much of the developing world. It affects approximately 1 out of every 10 people in the United States and is said to be the primary cause of adult-onset epilepsy. The infection creates cysts in the brain, causing seizures and headaches among other symptoms. To date no successful preventive treatment for neurocysticercosis exists.