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Neurocysticercosis Is Increasing in Industrialized Countries

SAN DIEGO—Neurocysticercosis, a parasitic disease that is the leading cause of epilepsy in Central and South America, is becoming more widespread in industrialized countries, according to a panel of investigators who presented findings here in Spanish at the annual meeting of the American Epilepsy Society.

In an interview on-site, one of the session moderators, Vicente Iragui, MD, PhD, discussed the etiology and modes of transmission that underlie the disease's increasing presence in the US and, by extension, in other industrialized countries. Dr. Iragui is professor of neuroscience at the University of California-San Diego, where he is the director of the Epilepsy Center.

“With migrating populations and high levels of global travel, a disease that was once relatively confined in Latin America is spreading to other areas of the world,” he said. “Neurocysticercosis has always been present in Latin America, although it is less common in Argentina, Uruguay, and Chile. It is also found in Africa and Southeast Asia.”

HISPANIC COMMUNITIES ARE VULNERABLE

In the US, the condition has developed in states with large Hispanic communities, such as California, New York, and Texas. “There is a wealth of knowledge about this disease in some countries in South America and Southeast Asia,” he said, noting the timeliness for discussing the condition at the meeting. “Neurologists here need to know more about this disease since we don't have much experience with it.”

[According to the most current data, there were 1,494 reports of neurocysticercosis in the US between 1980 and 2004 (Neurology 2004;63:1559–1564).]

CAUSES OF NEUROCYSTICERCOSIS

Neurocysticercosis is caused by tissue-invading larval forms of the pork tapeworm Taenia solium. It is spread by fecal-oral transmission among infected people or hogs that have the adult tapeworm. Poor water treatment techniques and under-cooked pork contribute to the spread. The disease is often transmitted by infected people who live in crowded, close quarters with other household members, or through ingestion of contaminated water, ice cubes, or raw fruit and vegetables.

After ingestion, the eggs travel from the host's gut to the bloodstream to various larvae, where fluid-filled cystic larvae develop. The lesions are rarely harmful in any organ system other than the CNS or the eye. Neurocysticercosis is the most serious complication. When the larvae die, the resultant inflammation causes seizures. The subsequent calcifications serve as a focus for recurrent seizures.

PREVENTION IS KEY

The key to eliminating neurocysticercosis is prevention, Dr. Iragui said. “The World Federation of Neurology has an ongoing education campaign regarding neurocysticercosis with goals of educating physicians and raising awareness and implementing measures to decrease its incidence,” he said.

He urged neurologists to become acquainted with this literature so that they can counsel patients more effectively when they are diagnosed and when they are traveling to endemic areas.

He added that several antiparasitic agents kill T. solium, the cysticercus. The swelling associated with the infection is typically treated with corticosteroids. Analgesics are used for headaches, and anticonvulsants for seizures. “In cases of hydrocephalus, surgery may be required,” he said.

ROLE IN EPILEPSY

“It's important for neurologists to understand the increasingly prominent role of neurocystocercosis as a cause of epilepsy,” said Mitchell Wallin, MD, MPH, in a phone interview. Dr. Wallin, who has surveyed the literature on the condition, is a clinical associate director of the Multiple Sclerosis Center of Excellence at the Veterans Affairs Medical Center in Washington, DC.

“We've seen more of this disease in the US in areas where people of Hispanic descent have immigrated, and therefore, it has spread to every major city in the country.”

“Because we live in a global world, many diseases that we associate with developing countries are now seen in the US,” he said. “We need better tests for screening. We understand how it spreads, and therefore, the disease could be knocked out. However, it's not yet reportable in the United States.” Some states, such as California and Oregon, require reporting of the disease, which will facilitate understanding the extent of infections here.

ARTICLE IN BRIEF

Experts highlight the need for public awareness about neuroscystericosis, a condition that causes seizures, which has spread from Latin American countries to the US and other countries.

REFERENCES

• Wallin MT, Kurtzke JF. Neurocysticercosis in the United States: a review of an important emerging infection. Neurology 2004;63:1559–1564.
• Maguire JH. Tapeworms and seizures – treatment and prevention. N Engl J Med 2004;350:215–217.
• Carpio A. Neurocysticercosis: an update. Lancet 2002;2:751–763.
    • Cysticercosis Fact Sheet:www.cdc.gov/ncidod/dpd/parasites/cysticercosis/factsht_cysticercosis.htm