Clustering of Necropsy-Confirmed Porcine Cysticercosis Surrounding Taenia solium Tapeworm Carriers in Peru

Abstract

The pork tapeworm, Taenia solium, is among the leading causes of preventable epilepsy in the world and is common in rural areas of developing countries where sanitation is limited and pigs have access to human feces. Prior studies in rural villages of Peru have observed clusters of T. solium cysticercosis among pigs that live near human tapeworm carriers. Such spatial analyses, however, have been limited by incomplete participation and substandard diagnostic tests. In this study, we evaluated the association between necropsy-confirmed cysticercosis in pigs and their distance to T. solium tapeworm carriers in six villages in northern Peru. A total of six (1.4%) tapeworm carriers were detected using copro-antigen enzyme-linked immunosorbent assay and seven of 10 (70%) pigs belonging to the tapeworm carriers were found with viable cyst infection on necropsy. This was significantly greater than the prevalence of viable cyst infection among pigs living < 500 m (11%) and > 500 m (0.5%) from a tapeworm carrier (P < 0.001 for distance trend). Similar statistically significant prevalence gradients were observed after adjustment for possible confounders and for other pig-level outcomes including infection with > 10 viable cysts, degenerated cyst infection, and serological outcomes. This investigation confirms that porcine cysticercosis clusters strongly around tapeworm carriers in endemic rural regions of northern Peru and supports interventions that target these hotspots.

Force-of-infection of Taenia solium porcine cysticercosis: a modelling analysis to assess global incidence and prevalence trends

“…In addition, aggregated seroprevalence estimates obtained from systems where pigs are kept in different ways, such as in Uganda 37 , where pigs are kept either as “tethered” or “free-range”, could mask specific age-seroprevalence profiles. Clustering of PCC infection has also been documented in SSA 74 and Latin American settings 75 , further highlighting that population prevalence surveys may miss these dynamics in the absence of additional spatial analysis.…”

Understanding transmission and control of the pork tapeworm with CystiAgent: a spatially explicit agent-based model

“…Local variations in pig-raising practices, sanitation, diet, and migration all interact to create locally specific transmission patterns that differ from one endemic village to the next [17]. Even within villages, spatial heterogeneities caused by pig-roaming patterns and open defecation cause clustering that is important for a model to capture [18][19][20]. Importantly, incorporating underlying spatial and biological processes of T. solium transmission was highlighted in a recent report on the WHO 2030 goals [11], and there is evidence that models that fail to account for these heterogeneities are susceptible to overestimating the effect of control interventions [21] and yielding unrealistic predictions for achieving control and elimination targets [22].…”

Understanding transmission and control of the pork tapeworm with CystiAgent: a spatially explicit agent-based model

“…Local variations in pig-raising practices, sanitation, diet, and migration all interact to create locally specific transmission patterns that differ from one endemic village to the next [20]. Even within villages, spatial heterogeneities caused by pig-roaming patterns and open defecation cause clustering that is important for a model to capture [21][22][23]. Importantly, incorporating underlying spatial and biological processes of T. solium transmission was highlighted in a recent report on the WHO 2030 goals [13], and there is evidence that models that fail to account for these heterogeneities are susceptible to overestimating the effect of control interventions [24] and yielding unrealistic predictions for achieving control and elimination targets [25].…”