CDC Yellow Book 2024

Travel-Associated Infections & Diseases

Author(s): Paul Cantey, Sharon Roy




Most prominent where sanitary conditions are poor, and pigs have access to human feces


Immigrants and refugees
Long-term travelers
Travelers visiting friends and relatives


Follow safe food precautions

Avoid eating food cooked by someone who does not practice good hand hygiene

Practice good hand hygiene


Serologic testing: CDC’s Parasitic Diseases Branch (404-718-4745;

Infectious Agent

Cysticercosis is caused by Taenia solium, a cestode parasite.


Transmission occurs through ingestion of eggs excreted by a human carrier of the adult T. solium tapeworm via fecally contaminated food or through close contact with the carrier. Autoinfection is also possible. Larval cysts of T. solium infect brain, muscle, or other tissues. Eating undercooked pork containing cysticerci results in tapeworm infection (taeniasis), not human cysticercosis.


Cysticercosis occurs globally and is common where sanitary conditions are poor and where pigs have access to human feces. Endemic areas include Latin America, sub-Saharan Africa, East Asia, and India. Cysticercosis is uncommon in travelers, but is more likely in long-term travelers, in immigrants and refugees from endemic regions, and in people who visit friends and relatives in endemic areas.

Clinical Presentation

The latent period for cysticercosis ranges from months to decades. Symptoms depend on the number, location, and stage of cysts. The most important clinical manifestations are caused by cysts in the brain, where cysts can be parenchymal or extraparenchymal (ventricular, subarachnoid). The most common presentations are seizures and increased intracranial pressure. Other presentations include encephalitis, symptoms of space-occupying lesions (e.g., seizures), and hydrocephalus. Cysticercosis should be considered in any adult with new-onset seizures who comes from an endemic area or has had potential exposure to a tapeworm carrier.


Neuroimaging studies (e.g., CT, MRI) are required, and confirmatory serologic testing is often needed. Visualization of a scolex on neuroimaging is diagnostic. The most specific serologic test is the enzyme-linked immunotransfer blot (EITB), but results can be negative in ≥30% of patients with a single parenchymal lesion. The sensitivity of the test is also reduced in patients with only calcified lesions. The EITB is available through the Parasitic Diseases Branch at the Centers for Disease Control and Prevention (CDC). See instructions on how to submit a serum specimen for testing to CDC.


Control of symptoms is the cornerstone of cysticercosis therapy. Anticonvulsants, corticosteroids, or both might be indicated. Urgently manage increased intracranial pressure, if present. Antiparasitic treatment (albendazole, praziquantel) is not indicated for all presentations of neurocysticercosis; carefully consider the risks and benefits before starting treatment and consider expert consultation. Recommendations vary depending on whether the lesion is parenchymal or extraparenchymal; viable, enhancing, or calcified; has associated perilesional edema; and by location and number of lesions. For some intraventricular lesions, surgical intervention could be the treatment of choice.

In complicated cases, the priority is neurologic management (e.g., corticosteroids, mannitol), neurosurgery, or both. In 2018, the Infectious Diseases Society of America and the American Society of Tropical Medicine and Hygiene published guidelines for the clinical management of neurocysticercosis. Clinicians can contact CDC Parasitic Diseases Inquiries at 404-718-4745 or to obtain more information about diagnosis and treatment.


To reduce the risk for infection, travelers should follow food and water precautions (see Sec. 2, Ch. 8, Food & Water Precautions) and practice good hand hygiene to reduce the risk for possible autoinfection.

CDC website:

The following authors contributed to the previous version of this chapter: Susan Montgomery, Barbara L. Herwaldt, Sharon L. Roy

Del Brutto OH. Neurocysticercosis among international travelers to disease-endemic areas. J Travel Med. 2012;19(2):112–17.

Garcia HH, Gonzales I, Lescano AG, Bustos JA, Pretell EJ, Saavedra H, et al. Enhanced steroid dosing reduces seizures during antiparasitic treatment for cysticercosis and early after. Epilepsia. 2014;55(9):1452–9.

Garcia HH, Gonzales I, Lescano AG, Bustos JA, Zimic M, Escalante D, et al. Efficacy of combined antiparasitic therapy with praziquantel and albendazole for neurocysticercosis: a double-blind, randomized controlled trial. Lancet Infect Dis. 2014;14(8):687–95.

White AC, Coyle CM, Rajshekhar V, Singh G, Hauser WA, Mohanty A, et al. Diagnosis and treatment of neurocysticercosis: 2017 clinical practice guidelines by the Infectious Diseases Society of America (IDSA) and the American Society of Tropical Medicine and Hygiene (ASTMH). Clin Infect Dis. 2018;66(8):e49–75.