Immunotherapy for Porcine Cysticercosis: Implications for Prevention of Human Disease

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  • Department of Medicine, Addenbrooke's Hospital, Universidad Nacional Mayor de San Marcos, Asociacion Benefica Proyectos en Informatica, Salud, Medicina y Agricultura (PRISMA), Johns Hopkins School of Public Health and Hygiene, Universidad Peruana Cayetano Heredia, Division of Parasitic Diseases, Centers for Disease Control and Prevention, Cambridge, United Kingdom
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Taenia solium cysticercosis is an important cause of human disease in many developing countries. Porcine cysticercosis is a vital link in the transmission of this disease and impairs meat production. A treatment for porcine cysticercosis may be an effective way of preventing human disease that would also benefit pig farmers, facilitating control programs in disease-endemic regions. Previous research suggests that reinfection with cysticercosis or immunotherapy with cysticercal antigens may cause degeneration of cysticerci, potentially curing porcine cysticercosis. Therefore, a blinded, randomized, controlled study to assess the efficacy and safety of immunotherapy in 28 naturally parasitized pigs was performed. Four groups of pigs with similar weights were inoculated twice with membrane-enriched cysticercal antigens (MA), saline, aqueous-soluble crude cysticercal antigens (AA) in adjuvant (Freund's complete then incomplete), or adjuvant alone. Immunotherapy was well tolerated but had no consistent effect on the macroscopic appearance of cysticerci or eosinophil count. Histopathologic findings were variable, with both severe and minimal inflammatory reactions seen in adjacent cysticerci in all pigs. Nine (64%) of 14 pigs given immunotherapy developed new antibody bands on electroimmunotransfer blot compared with one (7%) of 14 control pigs (P < 0.01). Treatment with AA in adjuvant caused a significant increase in the proportion of cysticerci that failed to evaginate and were, therefore, not viable for infecting humans (34% for pigs given AA in adjuvant compared with 10% for adjuvant alone; P < 0.04). Although immunotherapy caused a statistically significant decrease in the viability of cysticerci, this immunologic reaction was not great enough to prevent human disease.

Author Notes

Other members of the Cysticercosis Working Group in Peru are Maritza Alvarez, Cesar Carcamo, Miguel Castro, Fernando Diaz, Genaro Herrera, Olga Li, Manuel Martinez, Elba Miranda, Teresa Montenegro, Jorge Naranjo, and Patricia Torres.