Spatial transferability of an agent-based model to simulate Taenia solium control interventions.

BACKGROUND: Models can be used to study and predict the impact of interventions aimed at controlling the spread of infectious agents, such as Taenia solium, a zoonotic parasite whose larval stage causes epilepsy and economic loss in many rural areas of the developing nations. To enhance the credibility of model estimates, calibration against observed data is necessary. However, this process may lead to a paradoxical dependence of model parameters on location-specific data, thus limiting the model's geographic transferability. METHODS: In this study, we adopted a non-local model calibration approach to assess whether it can improve the spatial transferability of CystiAgent, our agent-based model of local-scale T. solium transmission. The calibration dataset for CystiAgent consisted of cross-sectional data on human taeniasis, pig cysticercosis and pig serology collected in eight villages in Northwest Peru. After calibration, the model was transferred to a second group of 21 destination villages in the same area without recalibrating its parameters. Model outputs were compared to pig serology data collected over a period of 2 years in the destination villages during a trial of T. solium control interventions, based on mass and spatially targeted human and pig treatments. RESULTS: Considering the uncertainties associated with empirical data, the model produced simulated pre-intervention pig seroprevalences that were successfully validated against data collected in 81% of destination villages. Furthermore, the model outputs were able to reproduce validated pig seroincidence values in 76% of destination villages when compared to the data obtained after the interventions. The results demonstrate that the CystiAgent model, when calibrated using a non-local approach, can be successfully transferred without requiring additional calibration. CONCLUSIONS: This feature allows the model to simulate both baseline pre-intervention transmission conditions and the outcomes of control interventions across villages that form geographically homogeneous regions, providing a basis for developing large-scale models representing T. solium transmission at a regional level.

Non-local validated parametrization of an agent-based model of local-scale Taenia solium transmission in North-West Peru.

The pork tapeworm, Taenia solium, is the cause of a preventable zoonotic disease, cysticercosis, affecting both pigs and humans. Continued endemic transmission of T. solium is a major contributor of epilepsy and other neurologic morbidity, and the source of important economic losses, in many rural areas of developing countries. Simulation modelling can play an important role in aiding the design and evaluation of strategies to control or even eliminate transmission of the parasite. In this paper, we present a new agent based model of local-scale T. solium transmission and a new, non-local, approach to the model calibration to fit model outputs to observed human taeniasis and pig cysticercosis prevalence simultaneously for several endemic villages. The model fully describes all relevant aspects of T. solium transmission, including the processes of pig and human infection, the spatial distribution of human and pig populations, the production of pork for human consumption, and the movement of humans and pigs in and out in several endemic villages of the northwest of Peru. Despite the high level of uncertainty associated with the empirical measurements of epidemiological data associated with T. solium, the non-local calibrated model parametrization reproduces the observed prevalences with an acceptable precision. It does so not only for the villages used to calibrate the model, but also for villages not included in the calibration process. This important finding demonstrates that the model, including its calibrated parametrization, can be successfully transferred within an endemic region. This will enable future studies to inform the design and optimization of T. solium control interventions in villages where the calibration may be prevented by the limited amount of empirical data, expanding the possible applications to a wider range of settings compared to previous models.

Taenia solium taeniasis/cysticercosis: From parasite biology and immunology to diagnosis and control.

Infection with the pork tapeworm (Taenia solium) is responsible for a substantial global burden of disease, not only restricted to its impact on human health, but also resulting in a considerable economic burden to smallholder pig farmers due to pig cysticercosis infection. The life-cycle, parasitology and immunology of T. solium are complex, involving pigs (the intermediate host, harbouring the larval metacestode stage), humans (the definitive host, harbouring the adult tapeworm, in addition to acting as accidental intermediate hosts) and the environment (the source of infection with eggs/proglottids). We review the parasitology, immunology, and epidemiology of the infection associated with each of the T. solium life-cycle stages, including the pre-adult/adult tapeworm responsible for human taeniasis; post-oncosphere and cysticercus associated with porcine and human cysticercosis, and the biological characteristics of eggs in the environment. We discuss the burden associated, in endemic settings, with neurocysticercosis (NCC) in humans, and the broader cross-sectoral economic impact associated both with NCC and porcine cysticercosis, the latter impacting food-value chains. Existing tools for diagnostics and control interventions that target different stages of the T. solium transmission cycle are reviewed and their limitations discussed. Currently, no national T. solium control programmes have been established in endemic areas, with further work required to identify optimal strategies according to epidemiological setting. There is increasing evidence suggesting that cross-sectoral interventions which target the parasite in both the human and pig host provide the most effective approaches for achieving control and ultimately elimination. We discuss future avenues for research on T. solium to support the attainment of the goals proposed in the revised World Health Organisation neglected tropical diseases roadmap for 2021-2030 adopted at the 73rd World Health Assembly in November 2020.

Systematic review of the effectiveness of selected drugs for preventive chemotherapy for Taenia solium taeniasis.

BACKGROUND: Preventive chemotherapy is a useful tool for the control of Taenia solium taeniasis and cysticercosis. The aim of this systematic review is to assess the scientific evidence concerning the effectiveness and safety of different drugs in preventive chemotherapy for T. solium taeniasis in endemic populations. METHODS: A systematic review was conducted of controlled and uncontrolled studies, assessing the efficacy and adverse effects (among other outcomes) of albendazole, niclosamide and/or praziquantel for preventive chemotherapy of T. solium taeniasis. A comprehensive search was conducted for published and unpublished studies. Two reviewers screened articles, completed the data extraction and assessment of risk of bias. A meta-analysis of cure rate and relative reduction in prevalence was performed. The protocol for this review was registered on the International prospective register of systematic reviews (PROSPERO), number CRD42018112533. RESULTS: We identified 3555 records, of which we included 20 primary studies reported across 33 articles. Meta-analyses of drug and dose showed that a single dose of praziquantel 10mg/kg, albendazole 400mg per day for three consecutive days, or niclosamide 2g, resulted in better cure rates for T. solium taeniasis (99.5%, 96.4% and 84.3%, respectively) than praziquantel 5mg/kg or single dose albendazole 400mg (89.0% and 52.0%, respectively). These findings have a low certainty of evidence due to high risk of bias in individual studies and heterogeneity in combined estimates. In relation to side-effects, most studies reported either no or only mild and transient side-effects within the first three days following drug administration for all drugs and doses. CONCLUSION: Evidence indicated that praziquantel 10mg/kg, niclosamide 2g, and triple dose albendazole 400mg were effective as taenicides and could be considered for use in mass drug administration programs for the control of T. solium taeniasis. Evidence was not found that any of these drugs caused severe side effects at the indicated doses, although the extent of the available evidence was limited.

Can We Recommend Practical Interventions to Prevent Neurocysticercosis?

The cystiSim model was used to compare strategies for the control of Taenia solium. A three-monthly intervention in pigs for 3 years was substantially more effective than biannual treatment for taeniasis in the human population for 5 years. The intervention period could be shortened further by combining pig and human interventions.

How to eliminate taeniasis/cysticercosis: porcine vaccination and human chemotherapy (Part 2).

BACKGROUND: The application of effective vaccines against pig cysticercosis and mass chemotherapy against pig cysticercosis and human taeniasis have shown the feasibility of interrupting the parasite's life cycle in endemic areas. METHODS: A mathematical model that divides the population into susceptible, infected, and vaccinated individuals is formulated. The model is based upon the life cycle of the parasite. Computer numerical simulation experiments to evaluate the impact of pig vaccination under different vaccination schedules, and combined intervention strategies including pig vaccination and anthelmintic treatment against human taeniasis are carried out. RESULTS: Vaccination against either pig cysticercosis or against human taeniasis will influence the transmission dynamics not only among vaccinees but also the dynamics of the other hosts as well. When the protective efficacy and/or the coverage rate is less than 100%, different mass interventions like vaccinating the pig population twice in combination with chemotherapeutic treatment against human taeniasis, the elimination of the infection in both pigs and humans can also be achieved. CONCLUSIONS: Our mathematical model has the potential for planning, and designing effective intervention strategies including both mass vaccination and/or chemotherapeutic treatment to eliminate pig cysticercosis, human taeniasis and human neurocysticercosis. The model can be adapted to any given community with mild, moderate endemicity, or even in hyperendemic regions.

Stepwise approach for the control and eventual elimination of Taenia solium as a public health problem.

BACKGROUND: Taenia solium taeniosis/cysticercosis is a public health and agricultural problem, especially in low-income countries, and has been ranked the top foodborne parasitic hazard globally. In 2012, the World Health Organization published a roadmap that called for a validated strategy for T. solium control and elimination by 2015. This goal has not been met, and validated evidence of effective control or elimination in endemic countries is still incomplete. Measuring and evaluating success of control programmes remains difficult, as locally acceptable targets have not been defined as part of the 2012 roadmap nor from other sources, and the performance of tools to measure effect are limited. DISCUSSION: We believe that an international agreement supported by the tripartite World Health Organization, Food and Agriculture Organization of the United Nations, and World Organisation for Animal Health is needed to facilitate endemic countries in publicising SMART (Specific, Measurable, Achievable/attainable, Relevant, Time-bound) country-level control target goals. These goals should be achievable through locally acceptable adoption of options from within a standardised 'intervention tool-kit', and progress towards these goals should be monitored using standardised and consistent diagnostics. Several intervention tools are available which can contribute to control of T. solium, but the combination of these - the most effective control algorithm - still needs to be identified. In order to mount control efforts and ensure political commitment, stakeholder engagement and funding, we argue that a stepwise approach, as developed for Rabies control, is necessary if control efforts are to be successful and sustainable. CONCLUSIONS: The stepwise approach can provide the framework for the development of realistic control goals of endemic areas, the implementation of intervention algorithms, and the standardised monitoring of the evaluation of the progress towards obtaining the control target goals and eventually elimination.

Notes and recommendations for the establishment of control programs for taeniasis and cysticercosis due to Taenia solium in PeruNotes and recommendations for the establishment of control programs for Taeniasis/cysticercosis in Peru. / Apuntes y recomendaciones para el establecimiento de programas de control de la teniasis / cisticercosis por Taenia Solium en el Perú.

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.

La neurocisticercosis es la infección del sistema nervioso por la larva (cisticerco) de la tenia del cerdo (Taenia solium). La neurocisticercosis es la mayor causa de epilepsia adquirida a nivel mundial y por ende un problema de salud pública global. De otro lado, la teniasis/cisticercosis por T. solium es una de las pocas infecciones consideradas potencialmente erradicables. Recientemente, un programa de eliminación de transmisión a gran escala en Tumbes, Perú, demostró la factibilidad de interrumpir la transmisión. Sobre la base de estos avances, se proponen una serie de lineamientos iniciales para poner las bases de programas de control regionales y nacionales de la teniasis/cisticercosis, partiendo de intervenciones simples y factibles a nivel local.

Apuntes y recomendaciones para el establecimiento de programas de control de la teniasis / cisticercosis por Taenia solium en el Perú / Notes and recommendations for the establishment of control programs for taeniasis and cysticercosis due to Taenia solium in Peru

La neurocisticercosis es la infección del sistema nervioso por la larva (cisticerco) de la tenia del cerdo (Taenia solium). La neurocisticercosis es la mayor causa de epilepsia adquirida a nivel mundial y por ende un problema de salud pública global. De otro lado, la teniasis/cisticercosis por T. solium es una de las pocas infecciones consideradas potencialmente erradicables. Recientemente, un programa de eliminación de transmisión a gran escala en Tumbes, Perú, demostró la factibilidad de interrumpir la transmisión. Sobre la base de estos avances, se proponen una serie de lineamientos iniciales para poner las bases de programas de control regionales y nacionales de la teniasis/cisticercosis, partiendo de intervenciones simples y factibles a nivel local.

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.

Elimination of Taenia solium Transmission in Northern Peru.

BACKGROUND: Taeniasis and cysticercosis are major causes of seizures and epilepsy. Infection by the causative parasite Taenia solium requires transmission between humans and pigs. The disease is considered to be eradicable, but data on attempts at regional elimination are lacking. We conducted a three-phase control program in Tumbes, Peru, to determine whether regional elimination would be feasible. METHODS: We systematically tested and compared elimination strategies to show the feasibility of interrupting the transmission of T. solium infection in a region of highly endemic disease in Peru. In phase 1, we assessed the effectiveness and feasibility of six intervention strategies that involved screening of humans and pigs, antiparasitic treatment, prevention education, and pig replacement in 42 villages. In phase 2, we compared mass treatment with mass screening (each either with or without vaccination of pigs) in 17 villages. In phase 3, we implemented the final strategy of mass treatment of humans along with the mass treatment and vaccination of pigs in the entire rural region of Tumbes (107 villages comprising 81,170 people and 55,638 pigs). The effect of the intervention was measured after phases 2 and 3 with the use of detailed necropsy to detect pigs with live, nondegenerated cysts capable of causing new infection. The necropsy sampling was weighted in that we preferentially included more samples from seropositive pigs than from seronegative pigs. RESULTS: Only two of the strategies implemented in phase 1 resulted in limited control over the transmission of T. solium infection, which highlighted the need to intensify the subsequent strategies. After the strategies in phase 2 were implemented, no cyst that was capable of further transmission of T. solium infection was found among 658 sampled pigs. One year later, without further intervention, 7 of 310 sampled pigs had live, nondegenerated cysts, but no infected pig was found in 11 of 17 villages, including all the villages in which mass antiparasitic treatment plus vaccination was implemented. After the final strategy was implemented in phase 3, a total of 3 of 342 pigs had live, nondegenerated cysts, but no infected pig was found in 105 of 107 villages. CONCLUSIONS: We showed that the transmission of T. solium infection was interrupted on a regional scale in a highly endemic region in Peru. (Funded by the Bill and Melinda Gates Foundation and others.).

GPS Tracking of Free-Ranging Pigs to Evaluate Ring Strategies for the Control of Cysticercosis/Taeniasis in Peru.

BACKGROUND: Taenia solium, a parasitic cestode that affects humans and pigs, is the leading cause of preventable epilepsy in the developing world. T. solium eggs are released into the environment through the stool of humans infected with an adult intestinal tapeworm (a condition called taeniasis), and cause cysticercosis when ingested by pigs or other humans. A control strategy to intervene within high-risk foci in endemic communities has been proposed as an alternative to mass antihelminthic treatment. In this ring strategy, antihelminthic treatment is targeted to humans and pigs residing within a 100 meter radius of a pig heavily-infected with cysticercosis. Our aim was to describe the roaming ranges of pigs in this region, and to evaluate whether the 100 meter radius rings encompass areas where risk factors for T. solium transmission, such as open human defecation and dense pig activity, are concentrated. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we used Global Positioning System (GPS) devices to track pig roaming ranges in two rural villages of northern Peru. We selected 41 pigs from two villages to participate in a 48-hour tracking period. Additionally, we surveyed all households to record the locations of open human defecation areas. We found that pigs spent a median of 82.8% (IQR: 73.5, 94.4) of their time roaming within 100 meters of their homes. The size of home ranges varied significantly by pig age, and 93% of the total time spent interacting with open human defecation areas occurred within 100 meters of pig residences. CONCLUSIONS/SIGNIFICANCE: These results indicate that 100 meter radius rings around heavily-infected pigs adequately capture the average pig's roaming area (i.e., home range) and represent an area where the great majority of exposure to human feces occurs.

Testing pigs of non-technified rearing farms for serum antibodies against Taenia solium in a region of the state of São Paulo, Brazil / Anticorpos séricos contra Taenia solium em suínos de criações não tecnificadas em uma região do Estado de São Paulo, Brasil

Taenia solium is a zoonotic tapeworm of great importance in developing countries, due to the occurrence of human taeniasis and cysticercosis. Pigs have an important role in the biological cycle of the parasite as intermediate hosts. The scientific literature has been describing risk factors associated with the occurrence of this disease that must be avoided in countries with poor sanitation, in order to reduce the exposure of swine to the parasite eggs. This research focused on testing pigs of non-technified rearing farms for serum antibodies against Taenia solium in the region of Jaboticabal municipality, in the state of São Paulo, Brazil. The found prevalence was 6.82% (CI 95% 4.18 - 9.45) at animal level and 28.87% (CI 95% 16.74 - 40.40) at herd level. These figures are probably associated with low technification adoption during animal rearing in the studied area, which increased the exposure of the animals to risk factors associated with the occurrence of Taenia solium complex. The results found based on serological evidences of swine cysticercosis in the studied region serves as a warning to public sanitary authorities to improve public health and control T. solium.

A Taenia solium é uma importante zoonose com grande importância em países em desenvolvimento, devido a ocorrência de teníase e cisticercose em humanos. Os suínos possuem grande importância no ciclo biológico desse parasita como hospedeiros intermediários. A literatura científica descreve alguns fatores de risco associados com a ocorrência da enfermidade e que devem ser evitados em países com baixo saneamento básico a fim de reduzir a exposição dos suínos aos ovos do parasita. Assim, objetivou-se avaliar a presença de anticorpos séricos contra Taenia solium em suínos de criações não tecnificadas na região do Município de Jaboticabal, Estado de São Paulo, Brasil. A prevalência estabelecida foi de 6,82% (IC 95% 4,18 - 9,45) a nível animal e 28,87% (IC 16,74 - 40,40) nos rebanhos. Isso está provavelmente associado ao baixo nível de tecnificação adotado durante a criação dos animais na área avaliada, o qual aumenta a exposição dos animais aos fatores de risco associados ao complexo Taenia solium. Os resultados da ocorrência de cisticercose suína baseados em evidências sorológicas na região avaliada servem como um alerta as autoridades sanitárias para promover a saúde pública e controlar a Taenia solium.

Testing pigs of non-technified rearing farms for serum antibodies against Taenia solium in a region of the state of São Paulo, Brazil / Anticorpos séricos contra Taenia solium em suínos de criações não tecnificadas em uma região do Estado de São Paulo, Brasil

Taenia solium is a zoonotic tapeworm of great importance in developing countries, due to the occurrence of human taeniasis and cysticercosis. Pigs have an important role in the biological cycle of the parasite as intermediate hosts. The scientific literature has been describing risk factors associated with the occurrence of this disease that must be avoided in countries with poor sanitation, in order to reduce the exposure of swine to the parasite eggs. This research focused on testing pigs of non-technified rearing farms for serum antibodies against Taenia solium in the region of Jaboticabal municipality, in the state of São Paulo, Brazil. The found prevalence was 6.82% (CI 95% 4.18 - 9.45) at animal level and 28.87% (CI 95% 16.74 - 40.40) at herd level. These figures are probably associated with low technification adoption during animal rearing in the studied area, which increased the exposure of the animals to risk factors associated with the occurrence of Taenia solium complex. The results found based on serological evidences of swine cysticercosis in the studied region serves as a warning to public sanitary authorities to improve public health and control T. solium.(AU)

A Taenia solium é uma importante zoonose com grande importância em países em desenvolvimento, devido a ocorrência de teníase e cisticercose em humanos. Os suínos possuem grande importância no ciclo biológico desse parasita como hospedeiros intermediários. A literatura científica descreve alguns fatores de risco associados com a ocorrência da enfermidade e que devem ser evitados em países com baixo saneamento básico a fim de reduzir a exposição dos suínos aos ovos do parasita. Assim, objetivou-se avaliar a presença de anticorpos séricos contra Taenia solium em suínos de criações não tecnificadas na região do Município de Jaboticabal, Estado de São Paulo, Brasil. A prevalência estabelecida foi de 6,82% (IC 95% 4,18 - 9,45) a nível animal e 28,87% (IC 16,74 - 40,40) nos rebanhos. Isso está provavelmente associado ao baixo nível de tecnificação adotado durante a criação dos animais na área avaliada, o qual aumenta a exposição dos animais aos fatores de risco associados ao complexo Taenia solium. Os resultados da ocorrência de cisticercose suína baseados em evidências sorológicas na região avaliada servem como um alerta as autoridades sanitárias para promover a saúde pública e controlar a Taenia solium.(AU)

[Evaluation of the impact of a control program against taeniasis-cysticercosis (Taenia solium)]. / Evaluación del impacto de un programa de control de la teniasis-cisticercosis (Taenia solium).

OBJETIVE: The impact of a control program is evaluated to eventually eradicate taeniasis-cysticercosis (Taenia solium) based on education and vaccination of pigs. MATERIALS AND METHODS: The prevalence of porcine cysticercosis was estimated using tongue inspection, ultrasound and determination of antibodies, before and three years after the application in three regions of the state of Guerrero. RESULTS: A significant reduction in the prevalence of porcine cysticercosis of 7 to 0.5% and 3.6 to 0.3% estimated by tongue examination or ultrasound respectively (p<0.01) and a no significant decrease in seroprevalence from 17.7 to 13.3% were observed. CONCLUSIONS: The reduction of the prevalence of taeniasis-cysticercosis establishes the program's effectiveness in preventing infection. The sustained presence of antibodies, compatible with contact of Taenia solium or other related helminths, underlines the importance of maintaining interventions to achieve eradication.

Evaluación del impacto de un programa de control de la teniasis-cisticercosis (Taenia solium) / Evaluation of the impact of a control program against taeniasis-cysticercosis (Taenia solium)

Objetivo. Evaluar el impacto de un programa de control de la teniasis-cisticercosis por Taenia solium con fines de erradicación, basado en educación de la comunidad y vacunación de cerdos. Material y métodos. Se estimó la prevalencia de cisticercosis porcina por medio de la palpación de lengua, ultrasonido y presencia de anticuerpos en suero, antes de iniciar el programa y tres años después, en tres regiones del estado de Guerrero. Resultados. Se observó una reducción significativa en la prevalencia de cisticercosis porcina de 7 a 0.5% y de 3.6 a 0.3%, estimadas por examen de lengua y ultrasonido, respectivamente (p<0.01), y una disminución no significativa de la seroprevalencia de 17.7 a 13.3%. Conclusiones. La reducción de la prevalencia de teniasis-cisticercosis comprueba la efectividad del programa para prevenir la infección. La presencia sostenida de anticuerpos es compatible con continuos contactos con Taenia solium u otros helmintos relacionados, y señala la necesidad de mantener las intervenciones para lograr su erradicación.

Objetive. The impact of a control program is evaluated to eventually eradicate taeniasis-cysticercosis (Taenia solium) based on education and vaccination of pigs. Materials and methods. The prevalence of porcine cysticercosis was estimated using tongue inspection, ultrasound and determination of antibodies, before and three years after the application in three regions of the state of Guerrero. Results. A significant reduction in the prevalence of porcine cysticercosis of 7 to 0.5% and 3.6 to 0.3% estimated by tongue examination or ultrasound respectively (p<0.01) and a no significant decrease in seroprevalence from 17.7 to 13.3% were observed. Conclusions. The reduction of the prevalence of taeniasis-cysticercosis establishes the program's effectiveness in preventing infection. The sustained presence of antibodies, compatible with contact of Taenia solium or other related helminths, underlines the importance of maintaining interventions to achieve eradication.

Tamoxifen treatment in hamsters induces protection during taeniosis by Taenia solium.

Human neurocysticercosis by Taenia solium is considered an emergent severe brain disorder in developing and developed countries. Discovery of new antiparasitic drugs has been recently aimed to restrain differentiation and establishment of the T. solium adult tapeworm, for being considered a central node in the disease propagation to both pigs and humans. Tamoxifen is an antiestrogenic drug with cysticidal action on Taenia crassiceps, a close relative of T. solium. Thus, we evaluated the effect of tamoxifen on the in vitro evagination and the in vivo establishment of T. solium. In vitro, tamoxifen inhibited evagination of T. solium cysticerci in a dose-time dependent manner. In vivo, administration of tamoxifen to hamsters decreased the intestinal establishment of the parasite by 70%, while recovered tapeworms showed an 80% reduction in length, appearing as scolices without strobilar development. Since tamoxifen did not show any significant effect on the proliferation of antigen-specific immune cells, intestinal inflammation, and expression of Th1/Th2 cytokines in spleen and duodenum, this drug could exert its antiparasite actions by having direct detrimental effects upon the adult tapeworm. These results demonstrate that tamoxifen exhibits a strong cysticidal and antitaeniasic effect on T. solium that should be further explored in humans and livestock.

Prevention and control of Taenia solium taeniasis/cysticercosis in Peru.

Taenia solium is endemic in most of the world, causing seizures and other neurological symptoms. Transmission is mainly maintained in rural areas by a human to pig cycle. Despite claims on its eradicability, sustainable interruption of transmission has not yet been reported. This manuscript reviews the conceptual basis for control, available diagnostic and control tools, and recent experiences on control in the field performed in Peru along the past decade.

Distribuição e identificação das regiões de risco para a cisticercose bovina no estado do Paraná / Distribution and identification of risk areas for bovine cysticercosis in the state of Paraná, Brazil

A cisticercose bovina é um problema de saúde pública e animal amplamente difundido no Brasil, que repercute negativamente na produção de carne em diversos estados do país. Trata-se de uma das afecções mais ocorrentes nos abates sob inspeção sanitária tornando-se motivo de preocupação para frigoríficos e produtores, devido os prejuízos que acarreta. Pouco se conhece sobre a distribuição e a evolução do número de casos de cisticercose bovina no estado do Paraná. Diante do exposto este trabalho teve o objetivo realizar um levantamento retrospectivo sobre a ocorrência da cisticercose bovina, diagnosticada através do exame post-mortem pelo Serviço de Inspeção Federal do Estado do Paraná entre os anos de 2004 a 2008, além de determinar a distribuição dos casos no Estado, identificar as regiões com maiores chances de apresentarem casos da doença e analisar a perda econômica do Estado por conta das condenações por esta parasitose. Foi constatada prevalência de 2,23% cisticercose bovina no estado do Paraná. Durante o período analisado ocorreu uma redução estatisticamente significante (p<0,05) da prevalência de cisticercose bovina no estado. Nos anos de 2004-2008 foram condenadas 29.708.550 kg de carne bovina por cisticercose, acarretando prejuízos de ordem econômica. O estado do Paraná está conseguindo através da implantação do programa de controle do complexo teníase-cisticercose, uma evolução positiva já que conseguiu durante o período analisado diminuir a prevalência desta parasitose nos bovinos e consequentemente diminuir as perdas econômicas.

Bovine cysticercosis is a problem of public and animal health highly spread in Brazil, which has negative repercussions in meat production in several states. This is one of the most common diseases occurring in the slaughterhouses under sanitary inspection, becoming a concern for cold stores and producers, because of the losses that it entails. Little is known about the distribution and evolution of the number of cases of bovine cysticercosis in the state of Paraná. Given the above, this work aimed to perform a retrospective survey on the occurrence of bovine cysticercosis, diagnosed by post-mortem examination by the Federal Inspection Service of the State of Paraná from 2004 to 2008; determine the distribution of cases in the state; identify the areas that most likely present cases of the disease, and analyze the economic loss of the state due to the condemnations for this parasitosis. It has been found a 2.23% prevalence of bovine cysticercosis in the state of Paraná. During the period analyzed, there was a statistically significant reduction (p<0.05) of the prevalence of bovine cysticercosis in the state. In the years 2004-2008, 29,708,550 kg of beef were condemned for cysticercosis, leading to economic losses. The state of Paraná is getting, through the deployment of the control program for the taeniasis-cysticercosis complex, a positive development since it got, during the analysis period, to reduce the prevalence of this parasite in cattle and, thus, reduce the economic losses.

Distribuição e identificação das regiões de risco para a cisticercose bovina no estado do Paraná / Distribution and identification of risk areas for bovine cysticercosis in the state of Paraná, Brazil

A cisticercose bovina é um problema de saúde pública e animal amplamente difundido no Brasil, que repercute negativamente na produção de carne em diversos estados do país. Trata-se de uma das afecções mais ocorrentes nos abates sob inspeção sanitária tornando-se motivo de preocupação para frigoríficos e produtores, devido os prejuízos que acarreta. Pouco se conhece sobre a distribuição e a evolução do número de casos de cisticercose bovina no estado do Paraná. Diante do exposto este trabalho teve o objetivo realizar um levantamento retrospectivo sobre a ocorrência da cisticercose bovina, diagnosticada através do exame post-mortem pelo Serviço de Inspeção Federal do Estado do Paraná entre os anos de 2004 a 2008, além de determinar a distribuição dos casos no Estado, identificar as regiões com maiores chances de apresentarem casos da doença e analisar a perda econômica do Estado por conta das condenações por esta parasitose. Foi constatada prevalência de 2,23% cisticercose bovina no estado do Paraná. Durante o período analisado ocorreu uma redução estatisticamente significante (p<0,05) da prevalência de cisticercose bovina no estado. Nos anos de 2004-2008 foram condenadas 29.708.550 kg de carne bovina por cisticercose, acarretando prejuízos de ordem econômica. O estado do Paraná está conseguindo através da implantação do programa de controle do complexo teníase-cisticercose, uma evolução positiva já que conseguiu durante o período analisado diminuir a prevalência desta parasitose nos bovinos e consequentemente diminuir as perdas econômicas.(AU)

Bovine cysticercosis is a problem of public and animal health highly spread in Brazil, which has negative repercussions in meat production in several states. This is one of the most common diseases occurring in the slaughterhouses under sanitary inspection, becoming a concern for cold stores and producers, because of the losses that it entails. Little is known about the distribution and evolution of the number of cases of bovine cysticercosis in the state of Paraná. Given the above, this work aimed to perform a retrospective survey on the occurrence of bovine cysticercosis, diagnosed by post-mortem examination by the Federal Inspection Service of the State of Paraná from 2004 to 2008; determine the distribution of cases in the state; identify the areas that most likely present cases of the disease, and analyze the economic loss of the state due to the condemnations for this parasitosis. It has been found a 2.23% prevalence of bovine cysticercosis in the state of Paraná. During the period analyzed, there was a statistically significant reduction (p<0.05) of the prevalence of bovine cysticercosis in the state. In the years 2004-2008, 29,708,550 kg of beef were condemned for cysticercosis, leading to economic losses. The state of Paraná is getting, through the deployment of the control program for the taeniasis-cysticercosis complex, a positive development since it got, during the analysis period, to reduce the prevalence of this parasite in cattle and, thus, reduce the economic losses.(AU)

Immunological mechanisms involved in the protection against intestinal taeniosis elicited by oral immunization with Taenia solium calreticulin.

Oral immunization with functional recombinant Taenia solium calreticulin (rTsCRT) induces 37% reduction in tapeworm burden in the experimental model of intestinal taeniosis in hamsters. Furthermore, tapeworms recovered from vaccinated animals exhibit diminished length, being frequently found in more posterior parts of the small intestine. The aim of this study was to analyze the immunological mechanisms involved in protection in response to rTsCRT oral immunization. Hamsters were orally immunized with rTsCRT using cholera toxin (CT) as adjuvant, weekly for 4 weeks. Fifteen days after the last boost animals were challenged with four T. solium cysticerci. Reduction in the adult worm recovery and increased transcription of mRNA for IL-4 and IFN-γ in the mucosa of rTsCRT+CT immunized animals were observed. Immunization also induced goblet cell hyperplasia in the mucosa surrounding the implantation site of the parasite. Specific IgG and IgA antibodies in serum and fecal supernatants were detected after the second immunization, being more pronounced after challenge. Our data suggest that oral vaccination with rTsCRT+CT regulates a local expression of IL-4 and IFN-γ, stimulating secretion of IgA that, together with the increase of goblet cells and mucin production, could result in an unfavorable environment for T. solium promoting an impaired tapeworm development.