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Abstract and Introduction
Abstract
Cysticercosis has emerged as a cause of severe neurologic disease in the United States. We evaluated cysticercosis-related deaths in the United States for 1990-2002 by race, sex, age, state of residence, country of birth, and year of death. A total of 221 cysticercosis deaths were identified. Mortality rates were highest for Latinos (adjusted rate ratio [ARR] 94.5, relative to whites) and men (ARR = 1.8). The mean age at death was 40.5 years (range 2-88). Most patients (187 [84.6%]) were foreign born, and 137 (62%) had emigrated from Mexico. The 33 US-born persons who died of cysticercosis represented 15% of all cysticercosis-related deaths. The cysticercosis mortality rate was highest in California, which accounted for ~60% of all deaths. Although uncommon, cysticercosis is a cause of premature death in the United States. Fatal cysticercosis affected mainly immigrants from Mexico and other Latin American countries; however, US-born persons were also affected.
Introduction
Cysticercosis, a parasitic infection caused by the larval form of the pork tapeworm, Taenia solium, has been increasingly recognized as a cause of severe but preventable neurologic disease in the United States. Reports documenting hundreds of cases, mainly of neurocysticercosis, have drawn attention to this previously underrecognized disease.
Cysticercosis has a complex life cycle. The larval infection, cysticercosis, is transmitted through the fecal-oral route. Eggs from the adult tapeworm T. solium, which are directly infectious, are shed in the feces of a human tapeworm carrier and subsequently ingested by pigs, the usual intermediate host. The oncosphere embryos emerge from the eggs, penetrate the intestinal wall, and are disseminated by the bloodstream to various tissues where the larval stage, or cysticercus, develops. The cycle is completed when humans, the only naturally infected definitive host, consume raw or undercooked pork containing cysticerci, which attach to the small bowel and develop into the adult tapeworm. However, humans may also become infected with the larval stage when eggs are ingested, typically in contaminated food or water. Neurocysticercosis, the most severe form of the disease, occurs when larvae invade tissue of the central nervous system.
Cysticercosis in the United States affects mainly immigrants from Latin America, where the disease is endemic. However, cysticercosis acquired in the United States has been repeatedly documented over the past 15 years, and travel-related infection in US-born persons has been reported. Given the ongoing sizeable immigration from disease-endemic areas, cysticercosis will grow in clinical and public health importance; however, data on cysticercosis in the United States are lacking. The disease is not nationally reportable, few local jurisdictions require reporting, and surveillance systems for cysticercosis have rarely been implemented. In the absence of effective surveillance, the true prevalence of cysticercosis in the United States is largely unknown. Although several hospital-based series have provided valuable insights into the occurrence of cysticercosis, they reflect only a portion of actual cases and do not measure the true effect of the disease on the general population and at-risk populations. Moreover, few data exist on cysticercosis as a cause of death in the United States. To augment current information on the effect of cysticercosis in the United States, we evaluated national mortality records for cysticercosis-related deaths for the 13-year period 1990-2002.
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