Parasitic helminthic worms infect the central nervous system (CNS) of millions of people in developing countries. Infected people who visit or immigrate to nonendemic areas, including the United States, may present there. Worms may cause meningitis, encephalitis, cerebral masses, hydrocephalus, stroke, and myelopathy.

Neurocysticercosis is the most common parasitic infection of the central nervous system (CNS). The disease affects people who ingest the tapeworm Taenia solium, and it develops when the worm’s larvae build up in the muscles, eyes, skin, and CNS.

You get cysticercosis from eating food or drinking water contaminated with T. solium eggs or from not washing your hands after touching poop (feces) that has T. solium eggs in it. The eggs hatch in your gut (intestines) and the young (larval) tapeworms form cysts in other parts of your body, like your brain and your eyes.

But if they end up in any part of your central nervous system – your spine or brain – then they cause a form of disease that's called neurocysticercosis. And this particular form of the disease will range depending on your immune system and your health status and where exactly those larvae have ended up. It can cause headaches and seizures.