Overview
Cysticercosis is caused by the encystment of the larvae of the tapeworm Taenia solium; it is the most common ocular platyhelminth infestation in humans. Pigs are the intermediate hosts and humans are the definitive hosts for T. solium. In cysticercosis, humans become the intermediate host by ingesting eggs of T. solium from contaminated pork meat, vegetables, polluted water, or other material contaminated with human feces. After penetrating the intestinal wall, the embryo invades the bloodstream and can disseminate to the skin, brain, eye, and other tissues. Human helminthiasis and porcine cysticercosis have been known as long as medical records have been recorded; in fact, they were noted in the Ebers Papyrus (ca. 1500 bc) in Egypt and in the writings of Hippocrates. T. solium has a worldwide distribution, with higher incidence in Mexico, Africa, Southeast Asia, Eastern Europe, and South America. Some risk factors for human infestation have been described: older age groups, absence of sanitary facilities, poor formal education, poverty, and the inability to recognize infected pork. The age incidence for ocular involvement is preferentially the first four decades of life. Earlier reports failed to reveal a sex predilection, but recently a male preponderance of 3:1 was reported in 44 Indian patients. Bilateral involvement has rarely been found. Neurocysticercosis and ocular cysticercosis seem to be more common in Latin America, whereas skin disease is relatively more common in India.
