Notes and recommendations for the establishment of control programs for taeniasis and cysticercosis due to Taenia solium in Peru

Neurocysticercosis is a nervous system infection caused by the larvae (cysticercus) of the pork tapeworm (Taenia solium). Neurocysticercosis is the primary cause of acquired epilepsy worldwide and, therefore, a global public health problem. On the other hand, T. solium taeniasis/cysticercosis is one of very few infectious diseases considered to be potentially eradicable. Recently, a large-scale elimination program in Tumbes, Peru, demonstrated the feasibility of interrupting transmission. Based on these advances, a series of initial guidelines are proposed aimed at setting out the foundations for regional and national taeniasis/cysticercosis control programs, with simple and feasible local interventions as a starting point

Hospitalization Frequency and Charges for Neurocysticercosis, United States, 2003–2012

Neurocysticercosis, brain infection with Taenia solium larval cysts, causes substantial neurologic illness around the world. To assess the effect of neurocysticercosis in the United States, we reviewed hospitalization discharge data in the Nationwide Inpatient Sample for 2003–2012 and found an estimated 18,584 hospitalizations for neurocysticercosis and associated hospital charges totaling >US $908 million. The risk for hospitalization was highest among Hispanics (2.5/100,000 population), a rate 35 times higher than that for the non-Hispanic white population. Nearly three-quarters of all hospitalized patients with neurocysticercosis were Hispanic. Male sex and age 20–44 years also incurred increased risk. In addition, hospitalizations and associated charges related to cysticercosis far exceeded those for malaria and were greater than for those for all other neglected tropical diseases combined. Neurocysticercosis is an increasing public health concern in the United States, especially among Hispanics, and costs the US health care system a substantial amount of money

Feasibility of a Point-of-Care Test Based on Quantum Dots with a Mobile phone Reader for Detection of Antibody Responses

We developed a novel and portable fluorescent sensor that integrates a lateral flow assay with a quantum dot (Qdots) label and a mobile phone reader for detection of specific antibodies in human serum. We evaluated the utility of this assay to test for antibodies to the Taenia solium rT24H antigen. It was a retrospective study by examining 112 positive human sera from patients with neurocysticercosis (NCC) including samples from patients with single viable cyst (n = 18), two or more viable cysts (n = 71), and subarachnoid (racemose) cysts (n = 23). These samples were collected from previous study subjects in Lima, Peru under an approved study protocol in Peru. The sera were made anonymous under a protocol approved by the CDC Institutional Review Board. Definitive diagnosis of the subject was established by computed-tomography and/or magnetic resonance imaging. To test the specificity of the assay, we evaluated a panel of serum samples obtained from patients with other infections (n = 24), and serum samples from persons in the United States and Egypt who had not traveled outside their country, and therefore are presumed negative for cysticercosis (n = 128). The assay specificity in the negative panel was 99% (95–100%) while assay sensitivity was 89% (79–95%) in NCC patients with two or more viable cysts. Our assay has performance characteristics similar to those of traditional platforms for the detection of NCC and shows promise as a mobile phone reader-based point-of-care test for antibody detection

Evaluating Healthcare Claims for Neurocysticercosis by Using All-Payer All-Claims Data, Oregon, 2010–2013

To characterize the frequency of neurocysticercosis, associated diagnostic codes, and place of infection, we searched Oregon’s All Payer All-Claims dataset for 2010–2013. Twice as many cases were found by searching inpatient and outpatient data than by inpatient data alone. Studies relying exclusively on inpatient data underestimate frequency and miss less severe disease

Spatial Relationship Between \u3ci\u3eTaenia Solium\u3c/i\u3e Tapeworm Carriers and Necropsy Cyst Burden in Pigs

Background Taenia solium, a parasite that affects humans and pigs, is the leading cause of preventable epilepsy in the developing world. Geographic hotspots of pigs testing positive for serologic markers of T. solium exposure have been observed surrounding the locations of human tapeworm carriers. This clustered pattern of seropositivity in endemic areas formed the basis for geographically targeted control interventions, which have been effective at reducing transmission. In this study, we further explore the spatial relationship between human tapeworm carriers and infected pigs using necroscopic examination as a quantitative goldstandard diagnostic to detect viable T. solium cyst infection in pigs. Methodology/Principal findings We performed necroscopic examinations on pigs from 7 villages in northern Peru to determine the number of viable T. solium cysts in each pig. Participating humans in the study villages were tested for T. solium tapeworm infection (i.e., taeniasis) with an ELISA coproantigen assay, and the distances from each pig to its nearest human tapeworm carrier were calculated. We assessed the relationship between proximity to a tapeworm carrier and the prevalence of light, moderate, and heavy cyst burden in pigs. The prevalence of pig infection was greatest within 50 meters of a tapeworm carrier and decreased monotonically as distance increased. Pigs living less than 50 meters from a human tapeworm carrier were 4.6 times more likely to be infected with at least one cyst than more distant pigs. Heavier cyst burdens, however, were not more strongly associated with proximity to tapeworm carriers than light cyst burdens. Conclusion/Significance Our study shows that human tapeworm carriers and pigs with viable T. solium cyst infection are geographically correlated in endemic areas. This finding supports control strategies that treat humans and pigs based on their proximity to other infected individuals. We did not, however, find sufficient evidence that heavier cyst burdens in pigs would serve as improved targets for geographically focused control interventions

Validation of a Spatial Agent-Based Model for Taenia Solium Transmission (“cystiagent”) Against a Large Prospective Trial of Control Strategies in Northern Peru

Background: The pork tapeworm (Taenia solium) is a parasitic helminth that imposes a major health and economic burden on poor rural populations around the world. As recognized by the World Health Organization, a key barrier for achieving control of T. solium is the lack of an accurate and validated simulation model with which to study transmission and evaluate available control and elimination strategies. CystiAgent is a spatially-explicit agent based model for T. solium that is unique among T. solium models in its ability to represent key spatial and environmental features of transmission and simulate spatially targeted interventions, such as ring strategy. Methods/Principal findings: We validated CystiAgent against results from the Ring Strategy Trial (RST)–a large cluster-randomized trial conducted in northern Peru that evaluated six unique interventions for T. solium control in 23 villages. For the validation, each intervention strategy was replicated in CystiAgent, and the simulated prevalences of human taeniasis, porcine cysticercosis, and porcine seroincidence were compared against prevalence estimates from the trial. Results showed that CystiAgent produced declines in transmission in response to each of the six intervention strategies, but overestimated the effect of interventions in the majority of villages; simulated prevalences for human taenasis and porcine cysticercosis at the end of the trial were a median of 0.53 and 5.0 percentages points less than prevalence observed at the end of the trial, respectively. Conclusions/Significance: The validation of CystiAgent represented an important step towards developing an accurate and reliable T. solium transmission model that can be deployed to fill critical gaps in our understanding of T. solium transmission and control. To improve model accuracy, future versions would benefit from improved data on pig immunity and resistance, field effectiveness of anti-helminthic treatment, and factors driving spatial clustering of T. solium infections including dispersion and contact with T. solium eggs in the environment. Author summary: Neurocysticercosis, caused by the ingestion of Taenia solium eggs, is a major cause of human epilepsy around the world. A wide spectrum of tools to fight T. solium is are now available and include antiparasitic treatment for pigs and humans, porcine vaccines, and sanitation improvements; however, the ideal combination of interventions applied to populations to maximize effectiveness and feasibility is not known. Transmission models are one tool that can be used to compare and evaluate different intervention strategies, but no currently available T. solium models have been tested for accuracy. In this research, we validated our model (“CystiAgent”) by comparing simulations of the model to the results of a large-scale trial testing a variety of T. solium control interventions. The model was calibrated using observed epidemiological data from these villages and evaluated for its ability to reproduce the effect of T. solium control interventions. The validation showed that the model was able to reproduce the baseline levels of disease, but generally overestimated the effect that each intervention would have on transmission. These results will allow us to identify limitations of the current model to improve future versions, and represent a step forward in the creation of a tool to design and evaluate future programs to control and eliminate T. solium

Data file including CystiAgent simulation results, observed results from the Ring Strategy Trial, and all intervention settings for each village evaluated (n = 21 villages).

Data file including CystiAgent simulation results, observed results from the Ring Strategy Trial, and all intervention settings for each village evaluated (n = 21 villages)

Dataset for epilepsy figures (Tumbes region)

A dataset containing epilepsy figures (Tumbes region) associated with the PLOS Computational Biology paper, "CystiHuman: A model of human neurocysticercosis"