RESEARCH Neurocysticercosis in Radiographically Imaged Seizure Patients in U.S. Emergency Depar tments1 Samuel Ong,* David A. Talan,* Gregory J. Moran,* William Mower,* Michael Newdow,* Victor C.W. Tsang,† Robert W. Pinner,† and the EMERGEncy ID NET Study Group2 Neurocysticercosis appears to be on the rise in the United States, based on immigration patterns and pub- lished cases series, including reports of domestic acquisition. We used a collaborative network of U.S. emergency departments to characterize the epidemiology of neurocysticercosis in seizure patients. Data were collected prospectively at 11 university-affiliated, geographically diverse, urban U.S. emergency departments from July 1996 to September 1998. Patients with a seizure who underwent neuroimaging were included. Of the 1,801 patients enrolled in the study, 38 (2.1%) had seizures attributable to neurocys- ticercosis. The disease was detected in 9 of the 11 sites and was associated with Hispanic ethnicity, immi- grant status, and exposure to areas where neurocysticercosis is endemic. This disease appears to be widely distributed and highly prevalent in certain populations (e.g., Hispanic patients) and areas (e.g., Southwest). N eurocysticercosis is the most common parasitic disease of the central nervous system. It is endemic in many devel- oping countries and has been cited as the primary reason that “epilepsy” is twice as common in these countries as in more industrialized nations such as the United States (1). The preva- lence of neurocysticercosis in some of these developing coun- tries exceeds 10% (2,3), where it accounts for up to 50% of cases of late-onset epilepsy (4). International travel and immigration are bringing neuro- cysticercosis to areas where it is not endemic. Several case series have been published from a variety of institutions throughout the United States, especially in the Southwest (5– 10), but none has directly assessed the prevalence of neurocys- ticercosis. Domestic acquisition of the disease has been docu- mented not only in large, metropolitan centers that attract large numbers of immigrants but also in less urban areas of North and South Carolina (11). Local acquisition has even been dem- onstrated in such unlikely areas as an Orthodox Jewish com- munity, where it was attributed to the employment of domestic workers from Central and South American countries (12). Seizures are the most frequent, and often the only, clinical manifestation of neurocysticercosis; they occur in 70% to 90% of cases (10,13). Because seizure patients frequently go to emergency departments, we chose this setting to perform a prospective study to determine the prevalence and epidemiol- ogy of this disease. *Olive View-University of California at Los Angeles Medical Center, Syl- mar, California, USA; and †Centers for Disease Control and Preven- tion, Atlanta, Georgia, USA Materials and Methods This study was a prospective case series of patients who visited any of a network of 11 geographically diverse, univer- sity-affiliated, urban emergency departments (EMERGEncy ID NET) from July 1996 to September 1998. The approximate total annual visit census of these emergency departments is 900,000. Institutional review board approval for the study was obtained at all sites. A more detailed description of EMER- GEncy ID NET, including its administration and the processes of data transfer and compilation, has been published (14). Emergency department patients >5 years of age were enrolled in the study if they had a known or suspected seizure and had undergone neuroimaging, either computed tomogra- phy scanning (CT) or magnetic resonance imaging (MRI). Patients <5 years of age were excluded to avoid enrolling a 1Presented at the 1997 annual meeting of the Society for Academic Emergency Medicine. Washington, DC, May 1997. 2The following investigators and centers collaborated in the EMER- GEncy ID NET Study Group: Principal investigator, D. Talan; Coinvesti- gator, G. Moran; Director of Informatics and Biostatistics, W. Mower; Project Coordinator, M. Newdow; Assistant Director of Informatics, S. Ong; Centers for Disease Control and Prevention collaborators, R. Pin- ner, V.C.W. Tsang, and L. Conn; Executive Committee, D. Talan, G. Moran, C. Pollack, J. Jui, L. Slutsker, R. Pinner; Site Investigators, P. Cheney (University of New Mexico Health Sciences Center, Albuquer- que, NM), W. Chiang (Bellevue Hospital Center, New York, NY); L. Dunbar (Louisiana State University Health Science Center, New Orleans, LA), K. Heilpern (Emory University School of Medicine, Atlanta, GA), J. Jui (Oregon Health Sciences University, Portland, OR), D. Karras (Temple University School of Medicine, Philadelphia, PA), G. Moran (Olive View-UCLA Medical Center, Sylmar, CA), C. Pollack (Maricopa Medical Center, Phoenix, AZ), J. O’Brien (Orlando Regional Medical Center, Orlando, FL), J. Runge (Carolinas Medical Center, Charlotte, NC), and M. Steele (University of Missouri-Kansas City, Kan- sas City, MO). 608 Emerging Infectious Diseases • Vol. 8, No. 6, June 2002