Cysticercosis

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Caryn Bern, Susan Montgomery

Cysticercosis is caused by infection with the cestode parasite Taenia solium in the larval stage.

Cysticercosis is acquired by ingesting eggs excreted by a human carrier of the pork tapeworm, T. solium. Eating undercooked pork with cysticerci results in tapeworm infection (taeniasis), not human cysticercosis. Fecally contaminated food can transmit the disease, but epidemiologic studies suggest that close (such as household) contact with a tapeworm carrier is the most common risk factor. Tapeworm carriers can be infected by ingestion of eggs they themselves have excreted; patients with cysticercosis and their household contacts should have stool specimens examined for eggs.

Cysticercosis is common in all countries where sanitary conditions are poor or where pigs are raised with access to human feces (Latin America, Asia, and Africa). Cysticercosis is uncommon in returning travelers; 3 case reports have been published.

The latent period (before symptoms) is a median of 5 years (range, 1–30 years). Cysticercosis symptoms depend on the number, location, and stage of cysts. The most common location is brain parenchyma, with late-onset seizures. Other presentations include increased intracranial pressure, encephalitis, symptoms of space-occupying lesion, and hydrocephalus. Cysticercosis should be ruled out in any adult with first-onset seizures who comes from an endemic area.

Diagnosis is based on neuroimaging studies (CT or MRI) and confirmatory serologic testing. The most reliable serologic test is the enzyme-linked immunotransfer blot, but even this test may be negative in up to 30% of patients with a single parenchymal lesion. The test is more sensitive in serum than in cerebrospinal fluid.

Neurocysticercosis is uncommon in the United States, and the inexperienced clinician is advised to consult an infectious disease or tropical medicine specialist for diagnosis and treatment. Physicians can consult with CDC’s Division of Parasitic Diseases and Malaria to obtain information about diagnosis and treatment (dpdx@cdc.gov; www.dpd.cdc.gov/dpdx). Albendazole and dexamethasone are some of the drugs used for treatment. For some lesions, surgical intervention may be the treatment of choice.

Antiparasitic treatment should not be initiated in patients with heavy infections, cysticercotic encephalitis, or increased intracranial pressure, because dying cysts can worsen symptoms and cause increased inflammation and edema. In these cases, the priority is neurologic management (steroids, mannitol), neurosurgical management, or both.

No vaccine is available. No drugs for preventing infection are available. Preventive measures are aimed at avoiding consumption of fecally contaminated food.

Garcia HH, Del Brutto OH. Neurocysticercosis: updated concepts about an old disease. Lancet Neurol. 2005 Oct;4(10):653–61.
Garcia HH, Del Brutto OH, Nash TE, White AC, Jr., Tsang VC, Gilman RH. New concepts in the diagnosis and management of neurocysticercosis (Taenia solium). Am J Trop Med Hyg. 2005 Jan;72(1):3–9.