Loyola University Health System researchers said as many as 10 percent of Mexican citizens might be infected with the disease neurocysticercosis.
The scientists led by Assistant Professor Dr. James Belmares said neurocysticercosis is caused by a tapeworm found in pigs. They said a person can become infected with the parasite by eating undercooked pork and that person then can excrete tapeworm eggs, which can spread the disease through food, water or surfaces contaminated with feces.
Neurocysticercosis is most common in poor rural communities in developing countries with poor sanitation and hygiene and where pigs are allowed to roam freely and eat human feces.
Once inside the stomach, the tapeworm egg hatches, travels through the bloodstream and ends up in the muscles, brain or eyes where it can grow to more than a half inch long and become enveloped in a fluid-filled cyst.
Cysts in the muscles generally don't cause symptoms, but the researchers said cysts in the eyes can cause blurry vision, while cysts in the brain can cause headaches, encephalitis and dramatic seizures. Less common symptoms include confusion and difficulty with balance.
The research that included Dr. Adolfo Ramirez-Zamora, a former resident at Loyola, and Tomas Alarcon, appears in the journal Neurological Research.