Performance of Ag-ELISA in the diagnosis of Taenia solium cysticercosis in naturally infected pigs in Tanzania.

BACKGROUND: Taenia solium is a zoonotic parasite responsible for neurocysticercosis-a major cause of late-onset acquired epilepsy in humans. Lack of affordable, specific and sensitive diagnostic tools hampers control of the parasite. This study assessed the performance of an antigen detection enzyme-linked immunosorbent assay (Ag-ELISA) in the diagnosis of viable T. solium cysticercosis in naturally infected slaughter-age pigs in an endemic area in Tanzania. METHODS: A total of 350 pigs were bled before they were slaughtered and their carcases examined. Serum was analyzed for circulating antigens by using a monoclonal antibody-based B158/B60 Ag-ELISA. Each carcase was examined for the presence of Taenia hydatigena cysticerci and half carcase musculature together with the whole brain, head muscles, tongue, heart and diaphragm were sliced with fine cuts (< 0.5 cm) to reveal and enumerate T. solium cysticerci. Half carcase dissection can detect at least 84% of infected pigs. Prevalence and their 95% confidence intervals (CI) were calculated in Stata 12. Sensitivity, specificity, predictive values and likelihood ratios were determined. RESULTS: Twenty-nine pigs (8.3%, 95% CI: 5.6-11.7%) had viable T. solium cysticerci while 11 pigs had T. hydatigena cysticerci (3.1%, 95% CI: 1.6-5.5%). No co-infection was observed. Sixty-eight pigs (19.4%, 95% CI: 15.4-20%) tested positive on Ag-ELISA; of these, 24 had T. solium cysticerci and 7 had T. hydatigena cysticerci. Sensitivity and specificity were determined to be 82.7% and 86.3%, respectively. Positive and negative predictive values were 35.2% and 98.2%, respectively. Likelihood ratios for positive and negative Ag-ELISA test results were 6.0 and 0.2, respectively. There was a significant positive correlation between the titre of circulating antigens and intensity of T. solium cysticerci (r(348) = 0.63, P < 0.001). CONCLUSIONS: The Ag-ELISA test characteristics reported in this study indicate that the test is more reliable in ruling out T. solium cysticercosis in pigs, than in confirming it. Hence, a negative result will almost certainly indicate that a pig has no infection, but a positive result should always be interpreted with caution. Estimates of T. solium prevalence based on Ag-ELISA results should, therefore, be adjusted for test performance characteristics and occurrence of T. hydatigena.

Case Report: Three Cases of Neurocysticercosis in Central Africa.

Neurocysticercosis (NCC) is an infection prevalent in developing countries; however, it is neglected in the Democratic Republic of the Congo (DRC) and in sub-Saharan Africa. Here, we present three different cases seen in a consulting room in Lubumbashi. These cases are evidence that NCC is more common than it was previously thought in sub-Saharan Africa. Neurocysticercosis is a pathology-neglected and ignored infection, not only by the population but also by health professionals and health authorities in the DRC, and because of that, it is important to increase the research about NCC in the DRC to assess the prevalence and risk factors for NCC to assess the severity of the phenomenon and to help designing appropriate prevention and control measures.

Case Report: Neurocysticercosis Acquired in Australia.

Neurocysticercosis (NCC) is a disease caused by infection of the central nervous system with the larval stage of the tapeworm Taenia solium. This disease is endemic in many parts of the world, including Africa, Asia, and Latin America, where animal husbandry practices are common such that pigs reared for human consumption ingest feces from humans infected with T. solium. Neurocysticercosis is rarely acquired in economically affluent regions, including North America, Central Europe, Japan, and Australasia, and in countries where pork consumption is discouraged by religious or social practices. In these countries, NCC is usually diagnosed in immigrants or returning travelers who have spent time in endemic regions. Here, we report a case of NCC in a 25-year-old woman presenting with worsening visual symptoms in association with headache, diagnosed previously as a migraine with visual aura. This person had always lived in Australia and had never traveled overseas to a country endemic for T. solium. The unusual features of the clinical presentation and epidemiology are highlighted to raise physicians' awareness that attention needs to be paid to the risk of autochthonous infection occurring in non-endemic countries.

Diagnosis of Porcine Cysticercosis at Necropsy: When Is Enough, Enough?

Changes in the incidence of porcine cysticercosis is used commonly in the assessment of efforts to control the transmission of Taenia solium, the cause of human neurocysticercosis. Although cysticerci may occasionally occur in tissues other than the striated muscles, particularly the brain, infection in pigs can be diagnosed reliably by assessment of muscle tissue alone.

Update on the major imported helminth infections in travelers and migrants.

Helminth infections cause considerable morbidity worldwide and may be frequently underdiagnosed especially in areas of lower endemicity. Patients may harbor latent infections that may become symptomatic years or decades after the initial exposure and timely diagnosis may be critical to prevent complications and improve outcomes. In this context, disease in special populations, such as immunosuppressed patients, may be of particular concern. Heightened awareness and recent diagnostic developments may contribute to the correct management of helminth infections in nonendemic regions. A review of the main helminth infections in travelers and migrants (strongyloidiasis, taeniasis-neurocysticercosis and schistosomiasis) is presented, focusing on epidemiology, developments in diagnosis, treatment and prevention.

Modelling for Taenia solium control strategies beyond 2020.

The cestode Taenia solium is responsible for a considerable cross-sectoral health and economic burden due to human neurocysticercosis and porcine cysticercosis. The 2012 World Health Organization (WHO) roadmap for neglected tropical diseases called for the development of a validated strategy for control of T. solium; however, such a strategy is not yet available. In 2019, WHO launched a global consultation aimed at refining the post-2020 targets for control of T. solium for a new roadmap for neglected tropical diseases. In response, two groups working on taeniasis and cysticercosis mathematical models (cystiSim and EPICYST models), together with a range of other stakeholders organized a workshop to provide technical input to the WHO consultation and develop a research plan to support efforts to achieve the post-2020 targets. The workshop led to the formation of a collaboration, CystiTeam, which aims to tackle the population biology, transmission dynamics, epidemiology and control of T. solium through mathematical modelling approaches. In this paper, we outline developments in T. solium control and in particular the use of modelling to help achieve post-2020 targets for control of T. solium. We discuss the steps involved in improving confidence in the predictive capacities of existing mathematical and computational models on T. solium transmission, including model comparison, refinement, calibration and validation. Expanding the CystiTeam partnership to other research groups and stakeholders, particularly those operating in different geographical and endemic areas, will enhance the prospects of improving the applicability of T. solium transmission models to inform taeniasis and cysticercosis control strategies.

Taenia solium est un cestode qui entraîne une charge intersectorielle économique et sanitaire considérable en provoquant une neurocysticercose humaine et une cysticercose porcine. La feuille de route sur les maladies tropicales négligées, publiée en 2012 par l'Organisation mondiale de la Santé (OMS), appelait à développer une stratégie de contrôle validée pour T. solium ; cependant, cette stratégie n'est pas encore disponible à l'heure actuelle. En 2019, l'OMS a lancé une procédure de consultation mondiale visant à préciser les objectifs de contrôle de T. solium après 2020, afin de rédiger une nouvelle feuille de route sur les maladies tropicales négligées. Deux groupes qui travaillent sur des modèles mathématiques de taeniasis et cysticercose (modèles cystiSim et EPICYST) ainsi qu'une série d'autres intervenants ont donc organisé un atelier pour fournir une contribution technique à cette consultation et développer un programme de recherche destiné à soutenir les efforts de réalisation des objectifs ultérieurs à 2020. L'atelier a donné naissance à une collaboration, CystiTeam, qui s'intéresse à la biologie des populations, à la dynamique de transmission, à l'épidémiologie et au contrôle de T. solium en employant des méthodes de modélisation mathématique. Le présent document retrace l'évolution du contrôle de T. solium, en particulier l'usage de la modélisation pour contribuer à atteindre les objectifs d'après 2020 en la matière. Nous abordons les diverses étapes de renforcement de la confiance accordée aux capacités prédictives des modèles mathématiques et informatiques existants sur la transmission de T. solium, notamment la comparaison, l'optimisation, le calibrage et la validation des modèles. Élargir le partenariat CystiTeam en intégrant d'autres groupes de recherche et intervenants, surtout ceux opérant dans différentes zones géographiques et endémiques, accroîtra les chances d'amélioration de l'applicabilité pour les modèles de transmission de T. solium, et permettra ainsi d'établir des stratégies de lutte contre la taeniasis et la cysticercose.

El cestodo Taenia solium es responsable de una importante carga sanitaria y económica transversal debido a la neurocisticercosis humana y la cisticercosis porcina. En la hoja de ruta de la Organización Mundial de la Salud (OMS) de 2012 sobre las enfermedades tropicales desatendidas se solicitaba la elaboración de una estrategia validada para el control de T. solium; sin embargo, dicha estrategia aún no está disponible. En 2019, la OMS inició una consulta mundial destinada a perfeccionar los objetivos de control de T. solium aplicables a partir de 2020 con miras a elaborar una hoja de ruta nueva sobre las enfermedades tropicales desatendidas. Consecuentemente, dos grupos que trabajan en modelos matemáticos de teniasis y cisticercosis (modelos cystiSim y EPICYST), junto con un grupo de otros interesados, organizaron un seminario para contribuir técnicamente a la consulta de la OMS y elaborar un plan de investigación a fin de apoyar los esfuerzos para lograr los objetivos a partir de 2020. El seminario impulsó la formación de un equipo de colaboración, CystiTeam, para abordar la biología de la población, la dinámica de la transmisión, la epidemiología y el control de T. solium mediante enfoques de modelos matemáticos. En el presente documento se describen las novedades en el control de T. solium y, en particular, la aplicación de modelos para ayudar a lograr los objetivos a partir de 2020 sobre el control de T. solium. Se analizan las etapas necesarias para mejorar la confianza en las capacidades de predicción de los modelos matemáticos y computacionales existentes sobre la transmisión de T. solium, incluyendo la comparación, el perfeccionamiento, el ajuste y la validación de los modelos. La ampliación de la asociación CystiTeam a otros grupos de investigación e interesados, en particular los que operan en diferentes zonas geográficas y endémicas, reforzará las perspectivas de mejorar la aplicabilidad de los modelos sobre las transmisión de T. solium para fundamentar las estrategias de control de la teniasis y la cisticercosis.

Neurocysticercosis: A new concept and insight into basic and future pharmacotherapy.

Neurocysticercosis is a neurological infection caused by the larva of taenia solium. The larva infection may affect different parts of the human brain and spinal cord, leading to focal neurological deficit with/without inflammatory reactions. Neurocysticercosis is one of the major causes of epilepsy in the developing countries. It is of two types. One is extra-parenchymal neurocysticercosis in which cysticerci cysts at subarachinoid space and ventricles lead to obstructive hydrocephalus and increase in the intracranial pressure. The other type is intra-parenchymal neurocysticercosis in which the cysticerci cyst grows inside the brain parenchyma, causing the feature of space-occupying lesion. The common presentation of intra-parenchymal neurocysticercosis is secondary epilepsy which is due to focal lesion and/or local inflammatory reactions. Cysticidal therapy increases the risk of seizure due to the induction of host inflammatory reactions. Therefore, coadministration of corticosteroids reduces the risk of seizure through attenuation of inflammatory reactions and brain oedema. Praziquantel alone or in combination with albendazole is regarded as the basic cysticidal therapy against neurocysticercosis. Newer drugs and agents are recommended to overcome the partial failure of standard cysticidal therapy.

Implementation of a practical and effective pilot intervention against transmission of Taenia solium by pigs in the Banke district of Nepal.

Taenia solium is a zoonotic cestode parasite which causes human neurocysticercosis. Pigs transmit the parasite by acting as the intermediate host. An intervention was implemented to control transmission of T. solium by pigs in Dalit communities of Banke District, Nepal. Every 3 months, pigs were vaccinated with the TSOL18 recombinant vaccine (Cysvax, IIL, India)) and, at the same time, given an oral treatment with 30mg/kg oxfendazole (Paranthic 10% MCI, Morocco). The prevalence of porcine cysticercosis was determined in both an intervention area as well as a similar no intervention control area, among randomly selected, slaughter-age pigs. Post mortem assessments were undertaken both at the start and at the end of the intervention. Participants conducting the post mortem assessments were blinded as to the source of the animals being assessed. At the start of the intervention the prevalence of porcine cysticercosis was 23.6% and 34.5% in the control and intervention areas, respectively. Following the intervention, the prevalence of cysticercosis in pigs from the control area was 16.7% (no significant change), whereas no infection was detected after complete slicing of all muscle tissue and brain in animals from the intervention area (P = 0.004). These findings are discussed in relation to the feasibility and sustainability of T. solium control. The 3-monthly vaccination and drug treatment intervention in pigs used here is suggested as an effective and practical method for reducing T. solium transmission by pigs. The results suggest that applying the intervention over a period of years may ultimately reduce the number of tapeworm carriers and thereby the incidence of NCC.

Spontaneously Arrested Transmission of Cysticercosis in a Highly Endemic Village with a Very Low Migration Rate.

Taenia solium cysticercosis is difficult to eliminate without interventions or societal development. Atahualpa is a rural Ecuadorian village with documented low migration rate, where domestic pig raising is common and human cysticercosis is endemic. To assess neurocysticercosis (NCC) prevalence, 1,273 villagers aged ≥ 20 years underwent neuroimaging studies, which showed calcified lesions in 121 (9.5%) individuals, but no active disease. Likewise, positive reactions, apparently nonspecific, were found in only 3/200 subjects by the use of a monoclonal antibody-based enzyme-linked immunosorbent assay to detect T. solium antigens in urine. Only 2/418 pigs reacted to three antibody bands on serum western blot and none to more than three bands. This is the first time that spontaneously arrested T. solium transmission is documented in a known endemic village. Understanding why active transmission stopped could provide insights on potential targets for control interventions. Atahualpa could provide an optimal scenario for longitudinal studies on the consequences of calcified NCC.

Clinical symptoms, diagnosis, and treatment of neurocysticercosis.

The infection of the nervous system by the cystic larvae of Taenia solium (neurocysticercosis) is a frequent cause of seizure disorders. Neurocysticercosis is endemic or presumed to be endemic in many low-income countries. The lifecycle of the worm and the clinical manifestations of neurocysticercosis are well established, and CT and MRI have substantially improved knowledge of the disease course. Improvements in immunodiagnosis have further advanced comprehension of the pathophysiology of this disease. This knowledge has led to individualised treatment approaches that account for the involvement of parenchymal or extraparenchymal spaces, the number and form of parasites, and the extent of degeneration and associated inflammation. Clinical investigations are focused on development of effective treatments and reduction of side-effects induced by treatment, such as seizures, hydrocephalus, infarcts, and neuroinjury.

Neurocysticercosis: new thoughts on controversial issues.

PURPOSE OF REVIEW: This review comments on the recent advances in the understanding of the controversial aspects of neurocysticercosis (NCC). RECENT FINDINGS: The number of autochthonous cases of NCC in nonendemic countries has increased during the last few years: it is likely that the migration of Taenia carriers from endemic areas is responsible for the increased prevalence of locally acquired NCC in these regions. NCC is mostly acquired from person to person, and the old theories crediting the environment as the main source of human infection with Taenia solium eggs must be abandoned. There is growing evidence suggesting that cysticercus granulomas (one of the most common forms of presentation of NCC) represent fresh infections and not old infections resulting from spontaneous destruction of viable cysticerci. Calcifications, often seen as inactive lesions producing no symptoms, are responsible for a sizable proportion of NCC-related seizures or headache. It is likely that exposure of parasitic antigens to the host's immune system is the cause of these manifestations. SUMMARY: During the last few years, there has been an increased knowledge on the controversial aspects of NCC, including epidemiology, mechanisms of disease acquisition, the natural involution of lesions in the brain parenchyma, and the role of calcifications as responsible for symptom occurrence.

Neurocysticercosis in the United States.

Neurocysticercosis (NCC) is typically considered a disease of the developing world. Nonetheless, NCC is also diagnosed in the developed world. The rise in the number of cases of NCC in developed countries, especially in the United States of America, has largely been driven by the influx of immigrants from endemic to non-endemic regions and the widespread access to neuroimaging. Cases of local transmission have also been documented particularly in the setting of a tapeworm carrier present in the household, which highlights the relevance of NCC as a public health problem in the USA. Although accurate incidence data in the USA are not available, estimates range from 0·2 to 0·6 cases per 100 000 general population and 1·5-5·8 cases per 100 000 Hispanics. We estimate that between 1320 and 5050 new cases of NCC occur every year in the USA. The number of NCC cases reported in the literature in the USA increased from 1494 prior to 2004 to 4632 after that date. Parenchymal cases remain the most commonly reported form of the disease; however, a slight increase in the percentage of extraparenchymal cases has been described in the most recent series. NCC is associated with significant morbidity resulting from hydrocephalus, cerebral edema, and seizures. Although uncommon, NCC is also a cause of premature death in the USA with a calculated annual age-adjusted mortality rate of at least 0·06 per million population.

Imaging of neurocysticercosis.

Neurocysticercosis (NCC) is an infection of the central nervous system by the Taenia solium larvae, and is the most common cause of acquired epilepsy in endemic regions. The natural history of parenchymal NCC lesions can be divided into 4 stages with unique imaging and clinical features. Evaluation of cysticerci is challenging on conventional magnetic resonance (MR) imaging and computed tomography, and is significantly improved with MR cysternography techniques. Differentiation of NCC lesions from metastatic disease and pyogenic abscesses can be improved with advanced MR imaging including (1)H nuclear MR spectroscopy, diffusion-weighted imaging, and MR perfusion imaging.

The association of living conditions and lifestyle factors with burden of cysts among neurocysticercosis patients in Ecuador.

We used baseline data on 154 symptomatic neurocysticercosis (NCC) patients in Ecuador to identify predictors of the burden of cysts. We ran logistic regression models with the burden of cysts as the outcome, defined as the number of cysts in the brain (1 vs >1), and having cysts in all 3 phases of evolution (active, transitional and calcifications) vs <3. These two outcomes are thought to be indicators of exposure dose and/or repeated exposure over time. The predictors examined were: living in a rural area, living on a dirt road, living in an adobe or wood house (vs brick/cement), no running water in the house, no bathroom in the house, having a domestic employee cook in the home, eating most meals at restaurants or street vendors, working in a manual labour job. We found that the odds of having multiple NCC cysts was higher among those working in manual labour (OR=3.5, p=0.004), and those who ate most meals outside the home had higher odds of having cysts in all 3 phases (OR=5.0, p=0.007). Burden of cysts may be a useful outcome when looking to identify exposure risk factors in the absence of an uninfected control group.

Neurocysticercosis in a 2-year-old boy infected at home.

A 2-year-old boy presented with seizures and two parenchymal brain ring-enhancing lesions. Diagnosis of neurocysticercosis was confirmed by positive serology and response to albendazole therapy. The patients's mother was a Taenia solium carrier, who had most likely infected the child through the fecal-oral route. Household contacts should always be investigated in children with neurocysticercosis. Proper identification and treatment of Taenia solium carriers will reduce the risk of further spread of the disease.

Cestode infestations: hydatid disease and cysticercosis.

Although humans can be definitive hosts for cestodes (tapeworms), major pathologic conditions occur during cestode larval stages when humans serve as the intermediate host for these parasites. The most relevant forms of human disease caused by cestode larvae are echinococcosis, caused by Echinococcus granulosus (cystic echinococcosis) and Echinococcus multilocularis (alveolar echinococcosis), and cysticercosis, caused by Taenia solium. These infections occur worldwide, but their relevance is particularly high in developing countries, where poor hygiene conditions facilitate the transmission of the parasites. The therapeutic approach is often complex, requiring surgery and/or chemotherapy or, in the case of cystic echinococcosis, percutaneous treatments.