Cysticercosis is a tissue infection caused by the young form of the pork tapeworm. People may have few or no symptoms for years. In some cases, particularly in Asia, solid lumps of between one and two centimeters may develop under the skin. After months or years, these lumps can become painful and swollen and then resolve. A specific form called neurocysticercosis, which affects the brain, can cause neurological symptoms. In developing countries, this is one of the most common causes of seizures.
Cysticercosis is usually acquired by eating food or drinking water contaminated by tapeworms' eggs from human feces. Among foods egg-contaminated vegetables are a major source. The tapeworm eggs are present in the feces of a person infected with the adult worms, a condition known as taeniasis. Taeniasis, in the strict sense, is a different disease and is due to eating cysts in poorly cooked pork. People who live with someone with pork tapeworm have a greater risk of getting cysticercosis. The diagnosis can be made by aspiration of a cyst. Taking pictures of the brain with computer tomography (CT) or magnetic resonance imaging (MRI) is most useful for the diagnosis of disease in the brain. An increased number of a type of white blood cell, called eosinophils, in the cerebral spinal fluid and blood is also an indicator.