Blog #36: Hard to Believe: Worms in the Brain Cause Epilepsy

(This blog was originally posted on July 30, 2013)

 

 

 

 

Cysticercosis was not on our diagnostic radar screen in the eastern half of the United States during my neurology training in Cleveland over 40 years ago. Once I began practicing in Southern California, however, I found this affliction was common. Anyone who developed seizures would have a CT image of the brain. I soon learned that if small, white calcification spots appeared on the scan of someone who came from a Third World country, especially Latin America, it was most likely a case of cysticercosis in the brain, or neurocysticercosis. The white spots are old scars caused by dead, calcified pig tapeworm larvae. Colleagues in the Eastern United States were intrigued when we discussed this condition as so few Latin Americans resided in those regions several decades ago. Currently, neurocysticercosis is diagnosed throughout the United States.

Cysticercosis is infestation with the pig tapeworm whose larvae have spread throughout the victim’s body. Poor personal hygiene and inadequate food preparation is the usual mechanism for this illness. It occurs when a person ingests the microscopic eggs of the pig tapeworm (Taenia solium) which are eliminated from the intestines with bowel movements. Poor farmers throughout the world commonly fertilize their gardens with their families’ feces (commonly referred to as “night soil”). It is an inexpensive fertilizer. If the feces are contaminated with the T. solium eggs, they are likely to ingest the eggs with these vegetables or from unclean hands. Tapeworms have “learned” to survive through evolution, i.e., the worms live for years symbiotically with their human or pig hosts and cause very few symptoms.

Following ingestion, the eggs develop into tiny worm larvae that migrate through the stomach lining of the pig or person into the bloodstream and spread to the rest of the body, especially to muscles and the brain. If contaminated pork muscle infected with living larvae is eaten undercooked, the live larvae mature into tapeworms in the host’s intestines. These tapeworms give off eggs to continue the cycle. Lack of sanitary meat inspection contributes to the problem.

Cysticercosis is the most common cause of epilepsy in Latin America. The little worms in the brain can cause serious paralysis or even death. More often, they are enclosed by scar tissue, die and form calcified, shrunken corpses that remain throughout the patient’s lifetime. These scars frequently, but not always, irritate brain cells, resulting in epilepsy. This epilepsy can usually be controlled with anticonvulsant medications.

 

Lance Fogan, M.D. is Clinical Professor of Neurology at the David Geffen School of Medicine at UCLA. DINGS is his first novel.