Are we ready for Taenia solium cysticercosis elimination in sub-Saharan Africa?

The World Health Organization announced in November 2014 at the fourth international meeting on 'the control of neglected zoonotic diseases - from advocacy to action', that intervention tools for eliminating Taenia solium taeniosis/cysticercosis (TSTC) are in place. The aim of this work was to elucidate theoretical outcomes of various control options suggested for TSTC elimination in sub-Saharan Africa (SSA) over a 4-year period. Our current knowledge regarding T. solium epidemiology and control primarily builds on studies from Latin America. A simple transmission model - built on data from Latin America - has been used to predict the effect of various interventions such as mass treatment of humans, vaccination and treatment of pigs, and health education of communities, potentially leading to change in bad practices and reducing transmission risks. Based on simulations of the transmission model, even a 4-year integrated One Health approach fails to eliminate TSTC from a small community and in all simulations, the prevalence of human taeniosis and porcine cysticercosis start to rise as soon as the programmes end. Our current knowledge regarding transmission and burden of TSTC in SSA is scarce and while claiming to be tool ready, the selection of diagnostic and surveillance tools, as well as the algorithms and stepwise approaches for control and elimination of TSTC remain major challenges

Mapping occurrence of Taenia solium taeniosis/cysticercosis and areas at risk of porcine cysticercosis in Central America and the Caribbean basin

Background: This study aimed to map the occurrence of Taenia solium taeniosis/cysticercosis at national level within Central America and the Caribbean basin, and to map the distribution of porcine cysticercosis at first-level administrative subdivision level (department level) and the porcine population at risk. This zoonotic parasite is believed to be widely endemic across most of Latin America. However, there is little information readily available for Central America and the Caribbean basin. Taenia solium has been ranked the most important foodborne parasitic hazard globally and within endemic areas is a common cause of preventable epilepsy. Methods: We conducted a structured literature search in PubMed, supplemented and crossed-referenced with relevant academic databases, grey literature, and active searches in identified literature, to identify all records of T. solium presence in Central America and the Caribbean basin between 1986 and April 2017. To retrieve grey literature, government entities, researchers and relevant institutions across the region were contacted in an attempt to cover all countries and territories. Identified records containing data on porcine cysticercosis were geo-referenced to identify department level distribution and compared to modelled distributions of pigs reared under extensive production systems. Results: We identified 51 records of T. solium at the national level, covering 13 countries and an additional three countries were included based on World Organisation for Animal Health (OIE) reports, giving a total of 16 countries out of 41 with evidence of the parasite's presence. Screening records for porcine cysticercosis data at the departmental level confirmed porcine cysticercosis presence in 11 departments across six countries (Colombia, Guatemala, Honduras, Mexico, Nicaragua and Venezuela). Conclusions: When comparing these results to areas where pigs were kept in extensive production systems and areas where no information on porcine cysticercosis exists, it is apparent that porcine cysticercosis is likely to be underreported, and that a substantial part of the regional pig population could be at risk of contracting porcine cysticercosis. More detailed information on the distribution of T. solium and accurate burden estimations are urgently needed to grasp the true extent of this zoonotic parasite and the public health and agricultural problems it potentially poses

Temporal fluctuations in the sero-prevalence of <i>Taenia solium</i> cysticercosis in pigs in Mbeya Region, Tanzania

BACKGROUND: Porcine cysticercosis is an emerging agricultural problem in sub-Saharan Africa. This has been documented primarily through cross-sectional studies, however detailed knowledge of the transmission dynamics of this disease in sub-Saharan Africa is lacking. This study aims to describe seasonal variations in sero-prevalence of antigen ELISA positive porcine cysticercosis in an endemic area. METHODS: A longitudinal study composed of three cross-sectional surveys was carried out in Mbeya Region, Tanzania; the first two six months apart (March/April 2012 and October/November 2012) and the last eight months later (July/August 2013). Venous blood was collected from pigs in 22 villages and analysed using Ag-ELISA. RESULTS: In each survey between 800–1000 serum samples were collected. The first survey revealed a cysticercosis sero-prevalence of 15% (n = 822, 95% CI: 13-18%). The sero-prevalence had significantly increased to 24% (p < 0.001, χ2-test, n = 812, 95% CI: 21-27%) at the time of the 6 month follow-up. At 14-months the sero-prevalence had dropped to 20% (p = 0.053, χ2-test, n = 998, 95% CI: 18-23%). Overall, this was a reduction in sero-prevalence compared with a study conducted in 2007 in the same area, where 31% (186/600) of pigs were found positive. CONCLUSION: Confined pigs did not have a lower sero-prevalence compared to free roaming pigs in any of the three surveys. Several factors may have contributed to the observed fluctuations such as African swine fever or seasonal variation in local crop production practices. Also, as the Ag-ELISA assay used is not species specific, variation in transmission of Taenia hydatigena could potentially influence the results. The observed fluctuations contradict a theoretical model which predicts a stable equilibrium, which only considers a two-compartment (pig and human) model excluding the effect of the environment. Whether the disease has an endemic equilibrium, or undergoes fluctuations dependent on extrinsic and/or socio-economic factors remains to be elucidated

<i>Taenia solium</i> taeniosis/cysticercosis and the co-distribution with schistosomiasis in Africa

BACKGROUND: This study aimed to map the distribution of Taenia solium taeniosis/cysticercosis and the co-distribution with schistosomiasis in Africa. These two major neglected tropical diseases are presumed to be widely distributed in Africa, but currently the level of co-distribution is unclear. METHODS: A literature search on T. solium taeniosis/cysticercosis was performed to compile all known studies on the presence of T. solium and apparent prevalence of taeniosis and porcine cysticercosis in Africa. Studies were geo-referenced using an online gazetteer. A Bayesian framework was used to combine the epidemiological data on the apparent prevalence with external information on test characteristics to estimate informed district-level prevalence of taeniosis and porcine cysticercosis. Districts with T. solium taeniosis/cysticercosis presence were cross-referenced with the Global Neglected Tropical Diseases Database for schistosomiasis presence. RESULTS: The search strategies identified 141 reports of T. solium in Africa from 1985 to 2014 from a total of 476 districts in 29 countries, 20 with porcine cysticercosis, 22 with human cysticercosis, and 16 with taeniosis, in addition to 2 countries identified from OIE reports. All 31 countries were considered, on national scale, to have co-distribution with schistosomiasis. Presence of both parasites was confirmed in 124 districts in 17 countries. The informed prevalence of taeniosis and porcine cysticercosis were estimated for 14 and 41 districts in 10 and 13 countries, respectively. CONCLUSIONS: With the paucity of data, T. solium infection is grossly under-reported and expected to be more widespread than this study suggests. In areas where co-distribution occurs there is a need for increased emphasis on evaluation of integrated intervention approaches for these two helminth infections and allocation of resources for evaluating the extent of adverse effects caused by mass drug administration. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-015-0938-7) contains supplementary material, which is available to authorized users

CystiSim : an agent-based model for Taenia solium transmission and control

Taenia solium taeniosis/cysticercosis was declared eradicable by the International Task Force for Disease Eradication in 1993, but remains a neglected zoonosis. To assist in the attempt to regionally eliminate this parasite, we developed cystiSim, an agent-based model for T. solium transmission and control. The model was developed in R and available as an R package (http://cran.r-project.org/package=cystiSim). cystiSim was adapted to an observed setting using field data from Tanzania, but adaptable to other settings if necessary. The model description adheres to the Overview, Design concepts, and Details (ODD) protocol and consists of two entities D pigs and humans. Pigs acquire cysticercosis through the environment or by direct contact with a tapeworm carrier's faeces. Humans acquire taeniosis from slaughtered pigs proportional to their infection intensity. The model allows for evaluation of three interventions measures or combinations hereof: treatment of humans, treatment of pigs, and pig vaccination, and allows for customary coverage and efficacy settings. cystiSim is the first agent-based transmission model for T. solium and suggests that control using a strategy consisting of an intervention only targeting the porcine host is possible, but that coverage and efficacy must be high if elimination is the ultimate goal. Good coverage of the intervention is important, but can be compensated for by including an additional intervention targeting the human host. cystiSim shows that the scenarios combining interventions in both hosts, mass drug administration to humans, and vaccination and treatment of pigs, have a high probability of success if coverage of 75% can be maintained over at least a four year period. In comparison with an existing mathematical model for T. solium transmission, cystiSim also includes parasite maturation, host immunity, and environmental contamination. Adding these biological parameters to the model resulted in new insights in the potential effect of intervention measures

A common framework for using and reporting consumer purchase data (CPD) in foodborne outbreak investigations in Europe

Publisher Copyright: © 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Consumer purchase data (CPD) can be a powerful tool in the investigation of foodborne outbreaks through analyses of electronic records of food that individuals buy. The objective of this study was to develop a common framework for use of CPD in foodborne outbreak investigations using the expertise of European public health professionals from 11 European countries. We also aimed to describe barriers and limitations preventing CPD utilization. CPD are mainly gathered from supermarket loyalty programmes, smaller consortia, and independent supermarkets. Privacy legislation governing CPD was perceived as the most crucial barrier for CPD usage, but still resolvable. The main practical challenges were obtaining consumer consent for CPD usage, the associated workload, data access, format, and analysis. Harmonising methods and reporting across countries, standardised consent forms and electronic consent methods were identified as solutions. This guideline was developed to support outbreak investigators in overcoming barriers in using CPD, thereby increasing public health professionals’ application and value of this powerful investigation tool. In addition, we hope this framework will lead to more public health institutions, in collaboration with food safety authorities, making use of CPD in outbreak investigations in the future.Peer reviewe

Taenia solium taeniosis and cysticercosis literature in Tanzania provides research evidence justification for control:A systematic scoping review

Background Despite Taenia solium taeniosis/cysticercosis (TSTC) having been put high on the global agenda of neglected tropical diseases (NTDs), which over the last years has received a lot of attention, there has been no control programmes in place in sub-Saharan Africa, a highly endemic region. This could be attributed to lack of awareness of many stakeholders on the burden and impact of T. solium. This information is essential in guiding TSTC policies, practices and research agendas as well as encouraging cross-sectoral collaboration in the control of this important zoonotic parasite using a One Health approach. National elimination of the parasite is the foundation for global eradication. This will require that substantial country-level information is provided to all key stakeholders. We have mapped out TSTC research evidence in Tanzania to inform on disease burden and potential for integrated control measures. Methodology/Principal findings A scoping review of all TSTC studies undertaken in Tanzania and published up to December 2018 was conducted. The articles were searched from PUBMED, AJOL, Google Scholar and Google in general. Fifty-one (51) articles met the inclusion criteria and were reviewed. Prevalence of taeniosis of 2.3% - 5.2% was estimated based on copro-antigen ELISA while human cysticercosis of >16% was estimated based on serum antigen ELISA (Ag-ELISA) or IgG Western Blot. Neurocysticercosis (NCC) contributed significantly to epilepsy in adults. Farm prevalence of porcine cysticercosis were 6.0% - 17.4% (lingual examination) and 1.5% - 33.3% (Ag-ELISA). Slaughter-slab prevalence were 0% - 18.2% (routine meat inspection). Lacking latrines, watering pigs with river or pond water, and feeding pigs with potato peels were associated with porcine cysticercosis prevalence. Washing hands by dipping method increased the risk of human cysticercosis. In 2012, the number of DALYs/1000 person-years for NCC-associated epilepsy was 0.7 (95% UI, 0.2–1.6), around 5 million USD (95% UI, 797,535–16,933,477) were spent due to NCC-associated epilepsy and nearly 3 million USD (95% UI, 1,095,960–5,366,038) were potentially lost due to porcine cysticercosis. Three rounds of annual treatment of school-age children with praziquantel significantly reduced prevalence of taeniosis and porcine cysticercosis. Health education was efficacious in improving knowledge and attitudes favourable for control of TSTC while a single dose of oxfendazole 30 mg/kg body weight was efficacious in eliminating T. solium cysticerci from pig musculature. Conclusions/Significance The observed high burden of TSTC and the significant contribution of NCC to epilepsy in Tanzania warrant urgent interventions. Evaluation of best control options should make use of disease transmission dynamics models such as cystiSim, taking into account findings from the field based intervention studies. In addition, locally adapted management guidelines for people suffering from NCC are urgently needed