RESUMO
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.
Assuntos
Cisticercose , Doenças dos Suínos , Taenia solium , Teníase , Humanos , Animais , Suínos , Estudos Transversais , Doenças dos Suínos/epidemiologia , Doenças dos Suínos/prevenção & controle , Doenças dos Suínos/parasitologia , Cisticercose/epidemiologia , Cisticercose/prevenção & controle , Cisticercose/veterinária , Teníase/epidemiologia , Teníase/prevenção & controle , Teníase/parasitologiaRESUMO
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.
Assuntos
Taenia solium/fisiologia , Teníase/parasitologia , África/epidemiologia , Fatores Etários , Animais , Ásia/epidemiologia , América Central/epidemiologia , Cisticercose/diagnóstico , Cisticercose/epidemiologia , Cisticercose/parasitologia , Cisticercose/prevenção & controle , Humanos , Estágios do Ciclo de Vida , Prevalência , Fatores Sexuais , América do Sul/epidemiologia , Suínos , Doenças dos Suínos/diagnóstico , Doenças dos Suínos/epidemiologia , Doenças dos Suínos/parasitologia , Doenças dos Suínos/prevenção & controle , Taenia solium/crescimento & desenvolvimento , Taenia solium/imunologia , Teníase/diagnóstico , Teníase/epidemiologia , Teníase/prevenção & controleRESUMO
Zoonotic taeniasis caused by the adult stage of Taenia solium, Taenia saginata or Taenia asiatica are considered neglected tropical diseases by the World Health Organization. The life cycle of these 3 metazoan species is very similar and includes an intermediate host: pigs in the case of T. solium and T. asiatica, and cattle in the case of T. saginata. By eating meat (pork/T. solium, T. asiatica; beef/T. saginata) containing live cysticerci, humans develop taeniasis, which is practically asymptomatic but is the main risk factor for intermediate hosts to become infected. T. saginata causes bovine cysticercosis, while T. solium and T. asiatica cause swine cysticercosis, of veterinary and economic importance. T. solium cysticerci cause neurological disease in humans: neurocysticercosis. Cysticerci develop after ingesting microscopic eggs released from a human tapeworm carrier. Here we describe the life stages of the parasites, diagnosis, pathogenesis, symptomatology of neurocysticercosis, and prevention and control measures. Highlighting the need to validate diagnostic tools, treatments and vaccination in endemic areas, with the challenge of addressing the most vulnerable populations that lack resources. If people understand the transmission route, avoid eating uncooked or insufficiently cooked meat and have adequate hygienic habits, the life cycle of the 3 zoonotic Taenia species may be interrupted. In addition, we describe the growing field of immune response and immunomodulation elicited by the parasites, which may provide essential tools for diagnosis, treatment, control of taeniasis/cysticercosis, as well as for identification of parasite-derived immunomodulators that could aid in the treatment of emerging inflammatory diseases worldwide.
Assuntos
Neurocisticercose , Doenças dos Suínos/parasitologia , Taenia , Zoonoses/parasitologia , Animais , Humanos , Neurocisticercose/diagnóstico , Neurocisticercose/parasitologia , Neurocisticercose/veterinária , Suínos , Doenças dos Suínos/prevenção & controle , Doenças dos Suínos/transmissão , Taenia saginata , Taenia solium , Zoonoses/diagnósticoRESUMO
Cysticercosis has been included among the most important known zoonosis, not only because it causes damages to animals" health and consequent economic losses but also due to the severity of the disease in the human population. It is caused by the larval stage (metacestodes) of Taenia solium and Taenia saginata.Based on the interactive relationship existing among the adult and larval stages of these parasites and their hosts, this paper reviews the natural history and prevention of the disease. The subject is approached so as to include the taeniasis-cysticercosis complex transmission mechanisms both from animals to man (taeniasis), as presented in a previous article, and from man to animals (cysticercosis). Several aspects are emphasized: a) the role of cysticercosis carriers on the transmission of human taeniasis; b) the meaning of the silent course of the disease and of the nonspecific clinical manifestations; c) the importance of an epidemiological surveillance system to identify the risk groups and to establish preventive interventions; d) the direct preventive actions. These preventive actions are based on 1) the diagnosis and treatment of taenias is carriers, as supported by veterinary inspection detecting cysticercosis in the slaughter house, associating the cases with the of the affected animals herds and notification to health authorities; 2) environment sanitation rel
A cisticercose tem sido considerada uma das mais importantes zoonoses conhecidas, não apenas pelos agravos à saúde animal e consequentes implicações econômicas, mas também pela gravidade da doença na população humana. Seu agente causal é representado pela forma larvar da Taenia solium e da Taenia saginata. O presente artigo focaliza a história natural e consequente prevenção da doença, tendo como base a relação interativa existente entre as formas adulta e larvar dos referidos parasitas e seus correspondentes hospedeiros, cuja apreciação impõe uma abordagem dicotômica e complementar dos mecanismos de transmissão do complexo teníase - cisticercose, a saber: sentido animal x homem (teníase), apresentado no artigo anterior, e sentido homem x animal(cisticercose), indissociáveis, no contexto holístico da abordagem, enfatizando: a) o papel dos portadores de cisticercose na transmissão da teníase humana; b) o significado do curso silencioso da doença e da inespecificidade das manifestações clínicas; c) a importância de um sistema de vigilância epidemiológica, objetivando a identificação dos grupos de risco e a correspondente intervenção preventiva; d) as ações preventivas diretas, que estariam apoiadas: 1) no diagnóstico e tratamento dos portadores humanos da teníase, subsidiado operacionalmente pela Inspeção Veterinária, detectando os casos de cisticercose, associando-os com os reba
RESUMO
A global approach of the Human Taeniasis-Cysticercosis Complex must take into account the natural history of a biological agent that requires the interactive relationship with two vertebrate species for its persistence, one of them being necessarily the human species. In fact, man is the obligatory host of both Taenia solium and Taenia saginata adult stages, while pig and cattle are the larval stage natural hosts (Cysticerclls cellulosae and Cysticercus bovis respectively). The human taeniasis disease process is presented in the first part of this review, emphasizing some relevant aspects such as man"s importance as the only natural host able to harbor both T. solium and T. saginata adult form and his role in the cysticercosis transmission mechanism; the human infestation mechanism by eating viable cysticerci with raw and/or undercooked meat; the role of animal species as taeniasis source of infection; the mild pathology (lesions and symptom ) stressing the importance of the patient"s observation of faeces as to the presence of proglottis; the significance of identifying the taenia species when the patient is treated, as well as the importance of global preventive actions in disrupting the epidemiological chain of this agent in different critical points.
Ao apreciarmos o complexo Teníase Humana - Cisticercose devemos ter em mente a história natural de um agente biológico que, para sua persistência na natureza, necessita, obrigatoriamente, da participação de duas espécies hospedeiras, uma das quais é, necessariamente, a humana. A Taenia solium, por exemplo, em sua forma adulta, hospeda-se, naturalmente, no intestino delgado do ser humano e, em sua forma larvar, o Cysticercus cellulosae, no tecido muscular de suínos. O ser humano é, também, o hospedeiro obrigatório da forma adulta da Taenia saginata, enquanto que a correspondente forma larvar, o Cysticercus bovis, infecta o tecido muscular de bovinos. Neste primeiro artigo trataremos do processo doença intitulado Teníase Humana, salientando: a importância desta espécie, única hospedeira da forma adulta das duas tênias, bem como seu papel na transmissão da cisticercose; o mecanismo envolvido em sua infestação pela ingestão de cisticercos viáveis com carne crua ou mal cozida; a patologia (lesões e sintomas) discreta ressaltando a importância da observação, pelo paciente, da presença de proglotes nas fezes; o significado da identificação da espécie da tênia por ocasião do tratamento do paciente e a essencialidade das ações preventivas globais, buscando romper a cadeia epidemiológica deste agente em seus diferentes pontos críticos.
RESUMO
A global approach of the Human Taeniasis-Cysticercosis Complex must take into account the natural history of a biological agent that requires the interactive relationship with two vertebrate species for its persistence, one of them being necessarily the human species. In fact, man is the obligatory host of both Taenia solium and Taenia saginata adult stages, while pig and cattle are the larval stage natural hosts (Cysticerclls cellulosae and Cysticercus bovis respectively). The human taeniasis disease process is presented in the first part of this review, emphasizing some relevant aspects such as man"s importance as the only natural host able to harbor both T. solium and T. saginata adult form and his role in the cysticercosis transmission mechanism; the human infestation mechanism by eating viable cysticerci with raw and/or undercooked meat; the role of animal species as taeniasis source of infection; the mild pathology (lesions and symptom ) stressing the importance of the patient"s observation of faeces as to the presence of proglottis; the significance of identifying the taenia species when the patient is treated, as well as the importance of global preventive actions in disrupting the epidemiological chain of this agent in different critical points.
Ao apreciarmos o complexo Teníase Humana - Cisticercose devemos ter em mente a história natural de um agente biológico que, para sua persistência na natureza, necessita, obrigatoriamente, da participação de duas espécies hospedeiras, uma das quais é, necessariamente, a humana. A Taenia solium, por exemplo, em sua forma adulta, hospeda-se, naturalmente, no intestino delgado do ser humano e, em sua forma larvar, o Cysticercus cellulosae, no tecido muscular de suínos. O ser humano é, também, o hospedeiro obrigatório da forma adulta da Taenia saginata, enquanto que a correspondente forma larvar, o Cysticercus bovis, infecta o tecido muscular de bovinos. Neste primeiro artigo trataremos do processo doença intitulado Teníase Humana, salientando: a importância desta espécie, única hospedeira da forma adulta das duas tênias, bem como seu papel na transmissão da cisticercose; o mecanismo envolvido em sua infestação pela ingestão de cisticercos viáveis com carne crua ou mal cozida; a patologia (lesões e sintomas) discreta ressaltando a importância da observação, pelo paciente, da presença de proglotes nas fezes; o significado da identificação da espécie da tênia por ocasião do tratamento do paciente e a essencialidade das ações preventivas globais, buscando romper a cadeia epidemiológica deste agente em seus diferentes pontos críticos.
RESUMO
Cysticercosis has been included among the most important known zoonosis, not only because it causes damages to animals" health and consequent economic losses but also due to the severity of the disease in the human population. It is caused by the larval stage (metacestodes) of Taenia solium and Taenia saginata.Based on the interactive relationship existing among the adult and larval stages of these parasites and their hosts, this paper reviews the natural history and prevention of the disease. The subject is approached so as to include the taeniasis-cysticercosis complex transmission mechanisms both from animals to man (taeniasis), as presented in a previous article, and from man to animals (cysticercosis). Several aspects are emphasized: a) the role of cysticercosis carriers on the transmission of human taeniasis; b) the meaning of the silent course of the disease and of the nonspecific clinical manifestations; c) the importance of an epidemiological surveillance system to identify the risk groups and to establish preventive interventions; d) the direct preventive actions. These preventive actions are based on 1) the diagnosis and treatment of taenias is carriers, as supported by veterinary inspection detecting cysticercosis in the slaughter house, associating the cases with the of the affected animals herds and notification to health authorities; 2) environment sanitation rel
A cisticercose tem sido considerada uma das mais importantes zoonoses conhecidas, não apenas pelos agravos à saúde animal e consequentes implicações econômicas, mas também pela gravidade da doença na população humana. Seu agente causal é representado pela forma larvar da Taenia solium e da Taenia saginata. O presente artigo focaliza a história natural e consequente prevenção da doença, tendo como base a relação interativa existente entre as formas adulta e larvar dos referidos parasitas e seus correspondentes hospedeiros, cuja apreciação impõe uma abordagem dicotômica e complementar dos mecanismos de transmissão do complexo teníase - cisticercose, a saber: sentido animal x homem (teníase), apresentado no artigo anterior, e sentido homem x animal(cisticercose), indissociáveis, no contexto holístico da abordagem, enfatizando: a) o papel dos portadores de cisticercose na transmissão da teníase humana; b) o significado do curso silencioso da doença e da inespecificidade das manifestações clínicas; c) a importância de um sistema de vigilância epidemiológica, objetivando a identificação dos grupos de risco e a correspondente intervenção preventiva; d) as ações preventivas diretas, que estariam apoiadas: 1) no diagnóstico e tratamento dos portadores humanos da teníase, subsidiado operacionalmente pela Inspeção Veterinária, detectando os casos de cisticercose, associando-os com os reba