Introduction. La neurocysticercosis (NCC) est l'un des maladies helminthiques les plus courantes du SNC et elle cause de l'épilepsie symptomatique dans les régions pauvres. Il existe peu d'études communautaires sur cette zoonose et leurs comorbidités comme l'épilepsie et la NCC. Méthodologie. Dans la région nord du Pérou, trois études sur la communauté et une révision systématique ont été développés dont les objectifs étaient les suivants: a) évaluer la prévalence de la NCC asymptomatique, b) la prévalence de l'épilepsie associée à la cysticercose, c) la détermination de l'exposition à la cysticercose d) développer une intervention communautaire pour interrompre la transmission de la cysticercose. Résultats. 256 patients asymptomatiques qui avaient une tomodensitométrie (T) sans contraste, 48 (18%) avaient la NCC calcifiés. La prévalence de l'épilepsie trouvée était de 17.25 / 1000 habitants et la proportion de NCC en personnes atteintes d'épilepsie était de 39% (109/282). Le Western Blot (EITB-LLGP) pour la cysticercose a été positive dans le 40% des personnes atteintes d'épilepsie, et dans le 36,9% de la population générale. L'association entre la cysticercose et l'épilepsie avait un OR de 2,7 (95% CI 2.1 – 3.6, p <0,001). Le traitement massif avec niclosamide chez l'homme (n = 3), et plus la vaccination de la population porcine a été mis en oeuvre dans 107 communautés rurales de Tumbes. Aucun porc infecté avec la cysticercose n’a été trouvé en 105 des 107 communautés. Conclusions. (1) La NCC est un facteur contributeur de l'épilepsie, (2) La transmission de T. solium peut être réduite à échelle régionale. / Backgrounds. Neurocysticercosis is a parasitic infection of the brain and a common cause of epilepsy in poor regions. There are scarce community-based studies about its comorbidities as epilepsy and neurocysticercosis. Methods. In the northern region of Peru, we performed three community based-studies and one systematic review a) to assess the prevalence of asymptomatic NCC, b) the prevalence of epilepsy and epileptic seizures and NCC c) seroprevalence of cysticercosis (EITB-LLGP) and d) to perform a community intervention to interrupt the Taenia solium transmission. Results. Of the 256 residents who underwent CT scan, 48 (18.8%) had brain calcifications consistent with NCC. Lifetime prevalence of epilepsy was 17.25/1000, the proportion of NCC in people with epilepsy was 39% (109/282), and the seroprevalence of EITB-LLGP in individuals with epilepsy was 40% and between 23.4 to 36.9% in the general population. The association between CC and epilepsy had a OR of 2.7 (95% CI 2.1-3.6, p <0.001). Three rounds of mass treatment with niclosamida in humans and mass treatment and vaccination in pigs was implemented in 107 rural communities (n=81,170 people). No infected pigs with cysticercosis were found in 105 of 107 communities. Conclusion. NCC is a strong contributor of epilepsy and epileptic seizures. We showed that transmission of Taenia solium infection was interrupted on a regional scale in endemic regions in Peru / Introducción. La neurocisticercosis (NCC) es una de las enfermedades helmínticas más frecuentes del SNC y causa de epilepsia sintomática en regiones pobres. Hay escasos estudios basados en comunidad sobre esta zoonosis y sus comorbilidades la epilepsia y la NCC. Metodología. Se desarrollaron en la Región Norte del Perú tres estudios basados en la comunidad, y una revisión sistemática cuyos objetivos fueron: a) evaluar la prevalencia de NCC asintomática, b) la prevalencia de epilepsia asociada a cisticercosis, c) determinación de la exposición a cisticercosis y d) desarrollar una intervención comunitaria que interrumpa la transmisión de cisticercosis. Resultados. De 256 pacientes asintomáticos que tuvieron una tomografía axial computarizada (TAC) cerebral sin contraste, 48 (18%) tuvo una NCC calcificada. La prevalencia de epilepsia encontrada fue de 17.25/1000 habitantes y la proporción de NCC en personas con epilepsia fue de 39% (109/282). El Western Blot (EITB-LLGP) para cisticercosis fue positivo en el 40% de los individuos con epilepsia, y en el 36.9% de la población general. La asociación entre cisticercosis y epilepsia tuvo un OR de 2.7 (95% CI 2.1-3.6, p <0.001). El tratamiento masivo con niclosamida en humanos (n=3), y población porcina más vacunación fue implementada en 107 comunidades rurales de Tumbes; en 105 de 107 no hubo nuevos cerdos infectados con cisticercosis. Conclusiones. (1) La NCC es un factor contribuidor de epilepsia, (2) Se puede cortar la trasmisión de T. solium a escala regional.

Orientador: Cáris Maroni Nunes / Resumo: O complexo teníase-cisticercose é causado pelos cestódeos Taenia saginata e Taenia solium, que têm o homem como hospedeiro definitivo e obrigatório e os bovinos e os suínos, respectivamente, como hospedeiros intermediários. A presença da forma adulta destes cestódeos no intestino delgado causa pequenos danos ao homem, enquanto a presença das formas larvárias nos tecidos e órgãos causam lesões nos hospedeiros intermediários, resultando na cisticercose. O homem pode também ser hospedeiro ocasional da T. solium e desenvolver a cisticercose, quando da ingestão acidental de seus ovos. Uma das medidas de controle desta zoonose é a inspeção sanitária de bovinos e suínos ao abate, evitando assim que os parasitas completem seu ciclo biológico. Assim, o complexo teníase-cisticercose, além de ser um grave problema de saúde pública, é também um problema econômico na agropecuária, visto que as carcaças podem ser condenadas quando da presença de formas larvares ou terem seu valor reduzido. A neurocisticercose é a forma mais grave desta zoonose no homem e seu diagnóstico é realizado por meios imunológicos e/ou por exames de imagens, que permitem a visualização dos das lesões no sistema nervoso central. Já a teníase é diagnosticada por meio da pesquisa de proglotes ou de ovos das tênias nas fezes, os quais são indistinguíveis morfologicamente. O objetivo do presente estudo foi avaliar a ocorrência de teníase humana por meio da análise dos resultados de exames coproparasitológicos rotineirame... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The taeniasis-cysticercosis complex is caused by the cestodes Taenia saginata and Taenia solium, which have man as their definitive and mandatory host and cattle and swine, respectively, as intermediate hosts. The presence of the adult form of these cestodes in the small intestine causes minor damage to humans, while the presence of the larval forms in tissues/organs causes damage to the intermediate hosts, resulting in cysticercosis. Man can also be an occasional host of T. solium and develop cysticercosis when ingesting its eggs. One of the measures to control this zoonosis is sanitary inspection of cattle and pigs at slaughter in order to prevent the parasites from completing their biological cycle. Thus, in addition of being a serious public health problem the taeniasiscysticercosis complex is also an economic problem once the carcasses with the larval forms can be condemned or have a reduced value. Neurocysticercosis is the most severe form of this zoonosis in man and its diagnosis is done by immunological method and/or by imaging exams, which allow the visualization of the lesions in the central nervous system. Taeniasis is diagnosed by searching for proglottids and/or tapeworm eggs in feces, which are morphologically indistinguishable. The objective of the present study was to evaluate the occurrence of human taeniasis by analyzing the results of the coproparasitological exams routinely performed in a private clinical analysis laboratory at a city in São Paulo state, B... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2015-03-26T13:46:43Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1492276 bytes, checksum: 4d382ffe8ee028de0569c86987765f6b (MD5) Previous issue date: 2004-12-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study was carried out with the purpose to develop an serological diagnosis protocol of bovine cysticercosis for the ELISA test using two metacestodes antigens of Taenia crassiceps and three of Taenia solium. There were used 20 sera of experimentally infected cattle with T. saginata eggs, 60 of cattle with natural infection, diagnosed at slaughterhouses, five of cattle negative for cisticercose, reared in isolation, 55 of negative bovine in slaughterhouses and 10 of bovine with actinomicosis (n=2), actinobacilosis (n=1), fasciolosis (n=1) diagnosed at slaughterhouse and of experimentally infected cattle with Anaplasma marginale (n=3), Babesia sp. (n=2) and concomitant infection for Anaplasma marginale and Babesia bovis (n=1). There were used the total and fluid cistic antigens of T. Crassiceps metacestodes and escólex and membrane antigens of T. solium metacestodes in ELISA test, after previous characterization in polyacrylamide gel electrophoresis (PAGE) in gradient 5 to 20%. The better antigen concentration was 1 µg and the better sera and conjugated dilutions were 1:25 and 1:5.000, respectively. Although the T. solium antigens have provided the most sensibility values, the T. crassiceps antigens also showed good performance to the bovine cysticercosis diagnosis. Different control serum groups employed for the cut-off calculation had changed the ELISA test results. We can concluded that the ELISA test for antibodies detection presents deficiencies in the diagnosis of naturally infected animals that showed low sensibility (5 to 32%) for different antigens. However, for experimentally infected cattle, the sensibility was high, 75 to 90% for different antigens. The test could still be considered useful in the differentiation between the cisticercose and other diseases, due to its high specificity rates (81 to 100%). / A cisticercose bovina é uma zoonose que tem o ser humano como único hospedeiro definitivo. Além de sua importância para a Saúde Pública, esta parasitose acarreta prejuízos econômicos em matadouros, ao levar as carcaças acometidas a julgamento. Este trabalho teve como objetivo o desenvolvimento de um teste de diagnóstico sorológico da cisticercose bovina pelo teste ELISA empregando dois antígenos de larvas de Taenia crassiceps e três de Taenia solium. Foram utilizados 20 soros de bovinos infectados experimentalmente com ovos de T. saginata, 60 de bovinos com infecção natural, diagnosticados em matadouros, cinco de bovinos negativos para cisticercose, criados sob isolamento, 55 de bovinos considerados negativos em matadouros e 10 de bovinos portadores de actinomicose (n=2), actinobacilose (n=1), fasciolose (n=1) diagnosticados em matadouro e de bovinos infectados experimentalmente com Anaplasma marginale (n=3), Babesia sp. (n=2) e infecção mista por Anaplasma marginale e Babesia bovis (n=1). Foram empregados os antígenos total e vesicular de larva de Taenia crassiceps e total, de escólex e de membrana de larva de Taenia solium no teste ELISA, após prévia caracterização em eletroforese em gel de poliacrilamida (SDS-PAGE) sob gradiente 5 a 20%. Após a realização de ensaios de avaliação do desempenho do teste em duas etapas, sempre considerando o critério da amplitude da diferença entre densidades ópticas de soros-controle positivos e negativos, foram obtidos os resultados que se seguem. A concentração de 1 µg de antígeno por orifício foi a que proporcionou, na maioria das vezes, a maior diferenciação entre soros positivos e negativos com todos os cinco antígenos estudados. As diluições 1:25 de soros e 1: 5.000 de conjugado também foram as que se destacaram, à exceção do antígeno de líquido vesicular de larva de T. crassiceps, que teve melhor desempenho quando o conjugado foi diluído a 1:2.500 vezes. O leite desnatado foi a melhor substância bloqueadora dos sítios reativos remanescentes da placa. Embora os antígenos de larva de T. solium tenham proporcionado valores mais elevados de sensibilidade, os antígenos de larva de T. crassiceps também mostraram bom desempenho no diagnóstico de cisticercose bovina. A escolha de diferentes grupos de soroscontrole para o cálculo do ponto de corte interferiu de forma expressiva no desempenho do teste ELISA. Pode-se concluir que o teste ELISA para detecção de anticorpos apresenta deficiências no diagnóstico de animais destinados ao abate, em virtude de sua baixa sensibilidade (5 a 32%) para diferentes antígenos, quando se consideram soros de animais com infecção natural, geralmente discreta. No entanto, no caso de animais infectados experimentalmente, a sensibilidade se mostrou elevada, 75 a 90%, para diferentes antígenos. O teste ainda pode ser considerado útil na diferenciação entre a cisticercose e outras doenças, devido às suas elevadas taxas de especificidade (81 a 100%).

Human neurocysticercosis (NC) is an important but neglected cause of epilepsy in developing countries where the parasite occurs. Expression of single-chain variable fragment (scFv) antibodies on the surface of bacteriophage is widely used to prepare antibodies with pre-defined specificities. A phage antibody library was selected against peptides displayed on phages coupled to beads and total saline extract of Taenia solium metacestodes immobilized on microtiter plate wells. After two rounds of selection 96 phage clones of each panning were selected, tested for scFv expression and specificity to each target. Specific clones were further analyzed by ELISA (Enzyme-linked immunosorbent assay), Dot-blot, sequencing and immunofluorescence. After selection, three clones were used for antigen capture to characterize its targets for future immunodiagnostic assays development. Total saline extract was fractionated on ion exchange resin diethylaminoethyl (DEAE), and fractions were tested by ELISA to detect sera IgG from: NC, other parasites and health controls (40 each). The fractions with best diagnostic parameters (sensitivity, specificity, area under curve and likelihood ratio, calculated by TG-ROC) were selected and subjected to antigen capture using each purified scFv clone. Each captured fraction was tested by ELISA to detect IgG in 30 serum samples from each group. In immunofluorescence tests, no fluorescence was observed in negative controls, and all clones showed a non-uniform staining profile, and their targets were elucidated through mass spectrometry. After ion exchange fractionation and ELISA tests, DEAE S2 fraction showed to be the best one and was used to capture new antigens. DEAE S2 showed 93.3% specificity. Among all clones, A4 and B6 captured antigens from saline extract and DEAE S2 fraction, respectively, with the best diagnostic parameters. In conclusion, antibody phage display technology is a potential approach for the study of antigen-antibody interactions, which can be used to further elucidate the biology of interaction on neurocysticercosis and to capture new antigens with potential applications in NC diagnosis and therapeutics. / A neurocistocercose humana (NC) é uma doença muito importante, porém negligenciada e é a maior causa de epilepsia em países em desenvolvimento onde a parasitose ocorre. A expressão de fragmentos de cadeia única das regiões variáveis de anticorpo (scFv) na superfície de bacteriófagos é amplamente utilizada para obter anticorpos com especificidades pré-definidas. Uma biblioteca de anticorpos foi utilizada para a seleção de clones específicos à peptídeos expostos em fagos acoplados a beads e ao extrato salino total de Taenia solium (S) imobilizado em placas de microtitulação. Após dois ciclos de seleção, 96 clones de anticorpos foram selecionados contra cada alvo, testados para expressão do scFv e especificidade pelo alvo. Aqueles clones que se mostraram específicos foram melhor analisados por ELISA (Enzyme linked immunosorbent assay), Dot blot, sequenciamento e imunofluorescência. Três clones foram selecionados para serem utilizados na captura antigênica e caracterização do antígeno verdadeiro e para captura de novos antígenos com potencial aplicação em testes diagnósticos. O extrato S foi fracionado em resina de troca iônica diethylaminoethyl (DEAE) para obter frações que foram posteriormente testadas por ELISA para detectar IgG em amostras de soro de pacientes: com NC, outras parasitoses e saudáveis, 40 amostras cada grupo. A fração com melhores parâmetros diagnósticos (sensibilidade, especificidade, área sob a curva e likelihood ratio, calculadas por TG-ROC) foi selecionada e sujeita à captura antigênica usando cada clone de scFv purificado. Cada fração capturada foi testada por ELISA para detectar IgG em 30 amostras de soro de cada grupo. Nos testes de imunofluorescência, nenhuma fluorescência foi observada com os controles negativos e todos os clones mostraram um padrão de marcação não uniforme, seus antígenos alvo foram elucidados por espectrometria de massas. Após fracionamento por troca iônica e ELISA, a fração DEAE S2 se mostrou a melhor e foi utilizada para a captura de novos antígenos. A fração DEAE S2 mostrou especificidade de 93,3%. Dentre todos os clones, o A4 e o B6 capturaram antígenos do extrato S e fração DEAE S2, respectivamente, com os melhores parâmetros diagnósticos. Em conclusão a tecnologia de exposição de anticorpos em fagos é uma técnica potencial para o estudo de interações antígeno-anticorpo utilizadas para melhor elucidar a a biologia da interação na NC e para capturar novos antígenos potencialmente aplicáveis para o diagnóstico da NC. / Doutor em Imunologia e Parasitologia Aplicadas

Neurocysticercosis (NC) is a polymorphic disease and the immune response in human carrier is heterogenic. In this study, 35 primers were used for amplifications by Random Amplified Polymorphic DNA (RAPD) of Taenia solium metacestodes, from five different geographic areas in Brazil: 1) Distrito Federal (DF), Center West; 2) Barreiras (BA), Northeast and Southeast; 3) Hydro Basin of the Mosquito River (North of Minas Gerais, RM-MG), 4) São Paulo (SP) and 5) Uberaba (Minas Gerais, UB-MG). Metacestodes saline crude extracts of four populations (DF, BA, RM-MG e SP) were used for the detection of specific IgG antibodies by ELISA and Western Blotting (WB). A total of 157 serum samples of three groups, (G1): 49 NC patients; (G2): 68 patients with other helminthiasis: hydatidosis (10), taeniasis (20), strongyloidiasis (20), schistosomiasis (10) and hymenolepiasis (8); and (G3): 40 healthy individuals; were analyzed by ELISA. From these, the 98 serum samples were assayed by WB; G1 (49), G2 (39) and G3 (10). The genetic distances, in disagreement percentage, between the metacestode populations were calculated from of 15 RAPD markers and showed 49.5% (DF), 48% (BA), 38.5% (UBMG) and 28% (RM-MG and SP) of genetic distances. Six primers identified polymorphic fragments and the primers 26 (GGGTTTGGCA) and 29 (TCGCCAGCCA) allowed a better differentiation of populations. The fragments of 1000, 500 and 326 pb (pairs of bases) in the UB-MG and of 600 and 244 pb in RM-MG were amplified by primer 26. The fragments generated by primer 29 were 500, 800 and 1191 pb, 300 and 1377 pb, 1000 pb and 244 and 434 pb in SP, UB-MG, DF and BA populations, respectively. In G1, the positivity by ELISA was: 90% (DF), 69% (BA), 71% (MG) and 67% (SP). The DF extract was more antigenic than others (p=0.02). In WB, the 64-68 kDa antigens were recognized in all extracts, exclusively, in serum samples from active NC patients (p=0.001). Variation in banding pattern was detected between the extracts (p<0.05). In G2, the serum samples of hydatidosis patients presented from 70 to 90% positivity by ELISA in antigenic extracts (p<0.05); however, the bands recognition pattern in WB was different from that presented in G1 samples. The 77 kDa band was significantly identified in hydatidosis samples (p=0.0001). In conclusion, the T. solium populations analyzed showed genetic variability and antigenic differences. / A neurocisticercose (NC) constitui doença polimórfica, apresentando heterogeneidade da resposta imune no hospedeiro humano. Nesse estudo, o teste Random Amplified Polymorphic DNA (RAPD) foi utilizado com 35 primers na detecção de polimorfismo em metacestódeos de Taenia solium provenientes de cinco áreas geográficas distintas do Brasil: 1) Distrito Federal (DF), região Centro-Oeste; 2) Barreiras (BA), região nordeste e da região sudeste: 3) Bacia Hidrográfica do Rio Mosquito (norte de Minas Gerais, RM-MG), 4) São Paulo (SP) e 5) Uberaba (Minas Gerais, UB-MG). Os extratos salinos totais de metacestódeos de quatro populações (DF, BA, RM-MG e SP) foram utilizados na detecção de anticorpos IgG específicos pelo ELISA e Western Blotting (WB). As 157 amostras de soro de três grupos (G) de indivíduos: G1: 49 pacientes com NC; G2: 68 pacientes com outras helmintíases, sendo hidatidose (10), teníase (20), estrongiloidíase (20), esquistossomose (10) e himenolepíase (8) e G3: 40 indivíduos saudáveis (controles); foram analisadas pelo ELISA. Foram ensaiadas 98 amostras de soro: G1 (49), G2 (39) e G3 (10) pelo WB. As distâncias genéticas, por porcentagem de desacordo, foram de 49,5% (DF), 48% (BA), 38,5% (UB-MG) e 28% (RM-MG e SP) nas populações de metacestódeos, calculadas a partir de 15 marcadores de RAPD. Seis primers geraram fragmentos polimórficos nos isolados analisados, sendo que os primers 26 (GGGTTTGGCA) e 29 (TCGCCAGCCA) permitiram melhor diferenciação entre as populações, o primer 26 gerou os fragmentos de 1000, 500 e 326 pb (pares de bases) na amostra de UB-MG, e de 600 e 244 pb em RM-MG. O 29 gerou fragmentos em quatro das populações analisadas, sendo 500, 800 e 1191 pb em SP, 300 e 1377 pb em UBMG, 1000 pb no DF e 244 e 434 pb na BA. No G1, as freqüências de positividade no ELISA, foram: 90% (DF), 69% (BA), 71% (MG) e 67% (SP), sendo o extrato do DF mais antigênico que os demais (p = 0,02). No WB, o peptídeo de 64-68 kDa foi reconhecido em todos os extratos, exclusivamente, em amostras de pacientes com NC ativa (p=0,001). Detectou-se variação no padrão de reconhecimento de bandas entre os extratos (p<0,05). No G2, as amostras de soro de pacientes com hidatidose apresentaram de 70 a 90% de positividade no ELISA frente aos extratos analisados (p<0,05); porém, o padrão de reconhecimento de bandas no WB diferiu do apresentado pelas amostras do G1, sendo que a banda de 77 kDa foi significativamente identificada pelas amostras de pacientes com hidatidose (p=0,0001). Concluiu-se que as populações de T. solium analisadas nesse estudo, apresentaram variabilidade genética e diferenças de antigenicidade. / Doutor em Imunologia e Parasitologia Aplicadas

Se revisaron artículos de los últimos 10 años publicados en las bases de datos bibliográficas de PUBMED, SCOPUS y Web of Science. Los resultados del análisis indican que los cuadros de cisticercosis extraneuronal se pueden presentar en diferentes zonas del cuerpo como el músculo, los ojos, la cavidad oral, mama, tejido subcutáneo, corazón, pulmón, glándulas y riñón, siendo el de mayor prevalencia la cisticercosis muscular y el de menor la del corazón. Las fuentes bibliográficas indican que los casos de cisticercosis extraneuronal son raros, en especial si son aislados. Además, dentro de todos los métodos diagnósticos, el más recomendable por ser menos invasivo es la punción con aguja fina (PAAF). Asimismo, el tratamiento con albendazol es el más utilizado en los diferentes tipos de cisticercosis extraneuronal, sin embargo, el tratamiento quirúrgico es necesario en ciertos casos. / Articles from the last 10 years published in the bibliographic databases of PUBMED, SCOPUS and Web of Science were reviewed. The results of the analysis indicate that extraneuronal cysticercosis can occur in different areas of the body such as the muscle, eyes, oral cavity, breast, subcutaneous tissue, heart, lung, glands and kidney, the most prevalent being cysticercosis muscular and the one of minor the one of the heart. Bibliographic sources indicate that cases of extraneuronal cysticercosis are rare, especially if they are isolated. In addition, among all the diagnostic methods, the most recommended because it is less invasive is the fine needle puncture (FNA). Likewise, treatment with albendazole is the most used in the different types of extraneuronal cysticercosis, however, surgical treatment is necessary in certain cases. / Tesis

INTRODUCTION Taenia solium cysticercosis (CC) and taeniosis are zoonotic diseases mainly occurring in developing countries of Asia, Africa and Latin America. Humans are the only definitive host of the parasite harbouring the adult tapeworm in the small intestine (taeniosis). Gravid proglottids containing thousands of eggs are daily shed with the faeces in the environment. The pig intermediate host, through its coprophagic behaviour, may consume contaminated human faeces and consequently, ingest eggs that will further develop into the larval stage of the parasite in the muscles and the brain (cysticerci), causing porcine CC. Humans acquire infection with the adult tapeworm by consumption of undercooked or raw pork infected with cysticerci. Humans can also become infected by the cysts by accidental ingestion of T. solium eggs and develop human CC. In humans, cysts may lodge in muscles, subcutaneous tissues, eyes and/or central nervous system causing ocular CC and neurocysticercosis (NCC) in the two latter cases, respectively. While mainly asymptomatic in pigs, CC and particularly NCC may be responsible of severe health disorders in humans, seizures and epilepsy being the most common ones. In the last decade T. solium became the study target of research groups throughout the world and is now more in the focus of international health and animal health organizations. However, the disease remains neglected and many data gaps still hinder a comprehensive estimation of its burden. Therefore, the general objective of this thesis is the development of tools to estimate the impact of T. solium CC on both public health and veterinary public health in regions where the parasite occurs. For this purpose, four specific objectives are followed focusing on taeniosis, porcine and human CC in different endemic areas of the world. Firstly, a stochastic model is developed allowing the estimation of the monetary and health (disability adjusted life year, DALY) burden of CC in three endemic provinces of Cameroon and the identification of data gaps increasing the uncertainty around the disease burden estimates (Objective 1). Secondly, because there is incomplete knowledge on many CC burden assessment parameters, two protocols are designed to study specific factors that may affect the transmission dynamics of the parasite, and possibly, the disease burden estimation. Because the latter estimation may depend on the age of diseased individuals, a community-based study aims at determining the occurrence of human CC and at studying the age-related infection and transmission patterns of the parasite among a population living in an endemic area of Ecuador (Objective 2). The objective of a second field study conducted in the Democratic Republic of Congo is to determine the occurrence of porcine CC at different levels of the pig trade chain in order to detect any variation in the apparent prevalence figures of the disease (Objective 3). Finally, because none of the available tests for the diagnosis of human CC is a gold standard limiting the estimation of the disease occurrence to the apparent prevalence, and since sensitivity and specificity of the diagnostic tests have only been evaluated in clinical settings, i.e. infected diseased versus uninfected non-diseased individuals, a Bayesian approach is used to estimate the true prevalence of human CC and the performances of available immunological tools for its diagnosis in the framework of an epidemiological study (including uninfected and infected diseased and non-diseased individuals) (Objective 4). RESULTS 1. Development of a stochastic model for the estimation of the economic and health (DALY) burden of T. solium cysticercosis The first experimental section of this thesis aims at developing a stochastic model for the estimation of the monetary and health (DALY) burden of CC, taking 3 endemic provinces of Cameroon as example. Both cost and DALY estimations are applied. All necessary parameters are collected and imported in R software. Different probability distributions are used according to the type of information available for each of the parameters. Monte Carlo simulation techniques allow drawing a set of parameters from the underlying distributions through serial iterations. The number of people with NCC-associated epilepsy represents 1.0% of the local population, whereas the number of pigs diagnosed with CC corresponds to 5.6% of the local pig population. The total annual costs due to T. solium CC in West-Cameroon is estimated at 10,255,202 Euro (95% CR 6,889,04814,754,044), of which 4.7% are due to losses in pig husbandry and 95.3% to direct and indirect expenses associated with human CC. The average number of DALYs lost is 9.0 per thousand persons per year (95% CR 2.820.4; meaning that 9 years of life in perfect health per thousand inhabitants of this area are lost due to CC). This study provides the first estimates of the impact of CC in Cameroon and allows identifying the related economical, clinical and epidemiological necessary parameters and related data gaps. Moreover, the stochastic approach developed here allowed quantifying the uncertainty around the estimates due to the lack of knowledge on this neglected disease. 2. Study on the age-related infection and transmission patterns of human CC in an endemic area The second experimental part of this thesis aims at estimating the apparent prevalence of human CC in an endemic area of Ecuador using both serological antigen and antibody detection methods. Besides a high exposure to the parasite (25% of the sampled population had antibodies directed against T. solium cysticerci) contrasting with a low level of active infection (2.9% had circulating parasite antigens), this study shows that positivity patterns of both diagnostic tests strongly depend on the age of the subjects. The proportion of individuals showing antibodies directed against the larval stage of the parasite significantly increases till the age of 40 to become stable later. Simulation models incorporating insights from cohort study data and basic immunology principles are developed to explain the variations in antibody detection positivity pattern and to reflect the dynamics of exposure to the parasite. The simulations suggest a continual exposure to the parasite through all age categories but a variation of the rate of seroreversion depending on the number of exposures, or in other words, on the immunological status of the individuals. The models also indicate that at least 14% of the population of the community is yearly exposed to the parasite. On the other hand, the proportion of individuals infected by living cysticerci is significantly higher in the elderly. These findings agree with clinical observations in Mexico and Brazil. Immunosenescence could explain such an observation since a weaker immune system in the elderly would facilitate the establishment and maintenance of viable cysticerci in the muscles and in the brain in comparison with fully immunocompetent younger individuals. Our findings indicate that age-related CC infection may influence the CC burden estimates. 3. Occurrence of porcine cysticercosis at different levels of the pig trade flow in a suspected endemic area Based on the use of the enzyme-linked immunosorbent assay for the detection of circulating antigens of T. solium metacestodes (B158/B60 Ag-ELISA), the third experimental section of this thesis reports an apparent prevalence of about 40% of active CC in a pig population in a rural area of Bas-Congo (where pigs are reared) and in a pig population in different markets of Kinshasa (where pork is sold). This work also indicates that the marketing of cysticercotic pig may influence the transmission of the parasite. Indeed, while no significant difference is found in the proportion of active infections between the two sites, the intensity of infection is significantly higher in pigs sampled in the villages in Bas-Congo as compared to those in the markets in Kinshasa. It seems that massively infected animals are excluded at a certain level in the pig trade chain. Preliminary informal surveys on common practices in pig husbandry and pig trading indicate that pig farmers and/or buyers select the low infected animals and exclude those who are positive by tongue inspection at village level. More heavily infected pigs are subsequently used for villagers own consumption or sold at local (clandestine) markets. The influence of the cysticercotic pig marketing should be considered when estimating the animal disease burden. Accurate burden estimates will allow establishing and implementing effective food safety policies and regulations or improving the existent ones in order to control and prevent CC and taeniosis. 4. Estimation of the performances of available immunodiagnostic tools for the diagnosis of human CC in the framework of an epidemiological study The last experimental section of this thesis focuses on the use of Bayesian models to estimate the true prevalence of infection with and exposure to T. solium, and the characteristics of serological tests, namely the enzyme-linked immunosorbent assay for the detection of circulating antigens of the metacestode of T. solium (B158/B60 Ag-ELISA), the enzyme-linked immunoelectrotransfer blot assay (EITB) for the detection of antibodies directed against 7 specific T. solium glycoprotein antigens, and the ELISA for the detection of antibodies directed against crude cyst fluid extracts (Ab-ELISA), used in an epidemiological study setting (including uninfected and infected diseased and non-diseased individuals) in an Ecuadorian endemic area. The EITB and B158/B60 Ag-ELISA sensitivity and specificity estimates in the latter conditions are comparable to the same estimates in clinical settings. However, the present study demonstrates the importance of clearly defining a case when conducting such an exercise. Indeed, the sensitivity and specificity of EITB and B158/B60 Ag-ELISA are high for estimating the true prevalence of exposure to (proportion of individuals who have been in contact with the parasite during the precedent year, with or without development of cysticerci, and with or without (cured individuals) current infection with living cysticerci) and infection with T. solium (proportion of individuals currently infected with living cysticerci), respectively, but drop the other way around. In conclusion, since no gold standard test for human CC diagnosis is available, this study provides a tool for estimation of the true CC prevalence, which is essential for the disease burden assessment. CONCLUSIONS AND PERSPECTIVES Even though the World Health Organization (WHO) already drew the map of the global distribution of T. solium, data remain very limited in several parts of the world. Through a literature review and four experimental sections, this thesis shows that the burden of human and porcine CC may be non negligible and deserves a more global assessment. Moreover, this work allows depicting the disease data gaps more precisely and proposes some tools to deal with the lack of knowledge on this neglected zoonosis. The threat of misusing limited data is a fact and one could reject more global burden estimates based hereon. However, this should not be the main issue. The main concerns should rather focus on how to obtain estimates when only fragmentary data are available. For this purpose, two approaches may be considered: (1) a prospective approach aiming at developing more accurate taeniosis and CC diagnostic tools and at collecting more standardized data from different endemic areas of the world; (2) a retrospective approach aiming at using existing data in innovative ways, such as simulation, Bayesian and stochastic models and expert elicitation, may be a valid alternative. In conclusion, the development of new diagnostic and estimation tools is in progress to compensate for the lack of knowledge on taeniosis/CC and for the diagnostic test and study design limitations (including financial, technical and ethical restrictions). Efforts should be made to increase their availability to developing countries and to standardize study designs in order to produce reliable estimates to assess the global burden of T. solium CC. Once burden estimates are available, the cost-effectiveness of prevention and control programs can be tested and help national and international policy- and decision- makers in setting priorities in public health and veterinary public health policy, services and research. INTRODUCTION La cysticercose (CC) et la taeniose dues à Taenia solium sont des maladies zoonotiques sévissant principalement dans les pays en voie de développement dAsie, dAfrique et dAmérique Latine. LHomme est le seul hôte définitif du parasite, infesté par le ver adulte au niveau de lintestin grêle (taeniose). Des proglottis gravides, contenant des milliers dufs sont quotidiennement évacués avec les matières fécales humaines dans lenvironnement. Le porc, hôte intermédiaire coprophage, peut consommer ces matières fécales contaminées et, par conséquent, ingérer des ufs qui se développeront en stade larvaire au niveau des muscles et du cerveau (les cysticerques), causant ainsi la CC porcine. LHomme, en consommant de la viande de porc infestée (de cysticerques) crue ou mal cuite, sinfeste par le ver adulte bouclant ainsi le cycle. LHomme peut également sinfester par ingestion accidentelle dufs et développer la CC humaine. Chez ce dernier, les cysticerques peuvent se loger dans les muscles, le tissu sous-cutané, les yeux et le système nerveux central, causant, dans ces deux derniers cas, respectivement, la CC oculaire et la neurocysticercose (NCC). Alors que la CC est généralement asymptomatique chez le porc, la CC et tout particulièrement la NCC peuvent être responsables daffections sévères chez lHomme, les convulsions et crises dépilepsie étant les plus fréquentes dentre elles. Durant les dernières décennies, T. solium est devenu le sujet détude principal de plusieurs groupes de recherche à travers le monde ainsi que dorganisations internationales de santé publique et de santé animale. Cependant, le manque de données épidémiologiques et cliniques empêche toujours une estimation précise de son impact réel sur la santé. Cest pourquoi, lobjectif principal de cette thèse est de développer des outils permettant destimer limpact de la CC due à T. solium sur la santé publique et la santé publique vétérinaire. Dans ce but, quatre objectifs spécifiques sont fixés. Premièrement, un modèle stochastique est développé pour estimer limpact économique de la CC due à T. solium et son impact sur la santé (« disability adjusted life year », DALY) dans trois provinces du Cameroun. Cette première étude vise également à identifier les données lacunaires qui augmentent lincertitude autour des estimations (Objectif 1). Sur cette base, deux études épidémiologiques sont conduites dans des communautés endémiques dAfrique et dAmérique Latine, focalisées sur certains facteurs pouvant avoir une influence sur la transmission du parasite, et ainsi sur son impact sur la santé. Puisque lestimation de limpact de la CC sur la santé peut dépendre de lâge des individus malades, une étude de terrain a pour but détudier les relations entre la prévalence apparente de la CC et lâge des individus exposés et infestés dans une zone endémique dEquateur (Objectif 2). Une seconde étude de terrain vise à déterminer loccurrence de la CC porcine à différents niveaux de la filière de production et de commercialisation de la viande de porc dans une zone suspectée endémique de la République Démocratique du Congo (RDC) afin de détecter déventuelles variations de la prévalence apparente de la maladie (Objectif 3). Finalement, vu que la sensibilité et la spécificité des tests pour le diagnostic de la CC humaine ont uniquement été évaluées dans le cadre détudes cliniques, cest-à-dire chez des patients souffrant de CC versus des individus non infestés et asymptomatiques, et vu quaucun de ces tests nest un test parfait (test ayant une sensibilité et une spécificité de 100%), une approche bayésienne est appliquée pour estimer les performances de tests immunologiques disponibles dans le cadre dune étude épidémiologique, incluant des individus non infestés et infestés avec ou sans symptômes (Objectif 4). RESULTATS 1. Développement dun modèle stochastique pour lestimation de limpact économique et de limpact sur la santé (DALY) de la cysticercose due à T. solium Le coût monétaire et le nombre dannées de vie en bonne santé perdues en raison dune mortalité prématurée et/ou de la morbidité dues à la cysticercose (CC) (DALY) sont tous deux estimés dans trois provinces de lOuest du Cameroun. Tous les paramètres épidémiologiques et économiques nécessaires sont collectés et importés dans le logiciel R. Différentes distributions de probabilité sont utilisées en fonction du type dinformation disponible pour chacun dentre eux. Des techniques de simulation de Monte Carlo permettent les estimations finales sur la base des distributions de probabiltés. En tenant compte dune prévalence dépilepsie de 3,6%, le nombre dindividus souffrant dépilepsie associée à la NCC sélève à 1,0% de la population locale. Dautre part, le nombre de porcs diagnostiqués comme infestés correspond à 5,6% de la population porcine locale. Le coût annuel total associé à la CC à lOuest du Cameroun est estimé à 10255202 Euros (95% de la région de confidence (RC) : 6889048-14754044 Euros), desquels 4,7% sont dus aux pertes liées à la production porcine. Le coût par cas de CC humaine séleve à 194 Euros (95% RC : 147-253 Euros). Le nombre moyen de DALYs perdus par 1000 personnes et par an est de 9,0 (95% RC : 2,8 20,4). Cette étude permet une première quantification de limpact de la CC au Cameroun, recense les paramètres économiques, cliniques et épidémiologiques nécessaires à cette fin et le manque de données leur étant lié. De plus, lapproche stochastique utilisée ici permet de quantifier lincertitude autour de ces estimations due au manque de connaissance de cette maladie négligée. 2. Etude de la relation entre la prévalence et la transmission de la cysticercose et lâge des individus exposés et infestés La seconde section expérimentale de cette thèse a pour objectif destimer la prévalence apparente de la CC humaine dans une région endémique de lEquateur en utilisant des techniques sérologiques de détection dantigènes et danticorps. En plus dune exposition élevée au parasite (25% des individus ont des anticorps dirigés contre les cysticerques) contrastant avec une faible proportion dindividus infestés par des cysticerques vivants (3% des individus ont des antigènes circulants de cysticerques), cette étude montre que la positivité aux tests sérologiques dépend de lâge des individus. En effet, la proportion dindividus montrant une réaction humorale dirigée contre le stade larvaire du parasite augmente significativement jusquà lâge de 40 ans pour se stabiliser ensuite. Des modèles de simulation intégrant des données issues dune étude longitudinale ainsi que des principes de bases dimmunologie sont développés dans le but dexpliquer ces variations et de refléter certains aspects de la dynamique dexposition au parasite. Ces simulations suggèrent un taux dexposition au parasite stable à travers les différentes catégories dâge, mais une variation du taux de séroréversion dépendant du nombre de contacts préalables avec le parasite ou, en dautres mots, du statut immunologique des individus. Les modèles indiquent également quau moins 14% de la population sont annuellement exposés au parasite. Dautre part, la proportion des individus infestés par des cysticerques vivants est significativement plus élevée chez les personnes âgées de plus de 60 ans. Limmunosénescence pourrait expliquer ce phénomène, puisque un système immunitaire plus faible chez les personnes âgées pourrait faciliter létablissement et le maintien de cysticerques vivants au sein des muscles et du cerveau. Nos observations indiquent que lâge des individus malades pourrait influencer lestimation de limpact de la CC. 3. Occurrence de la cysticercose porcine à différents niveaux de la filière de la production de viande porcine dans une zone suspectée endémique Sur la base de lutilisation dun test immuno-enzymatique (« enzyme-linked immunosorbent assay », ELISA) pour la détection dantigènes circulants de cysticerques (B158/B60 Ag-ELISA), la troisième section expérimentale de cette thèse permet destimer une prévalence denviron 40% de CC active au sein dune population de porcs élevés traditionnellement dans une zone rurale de la province du Bas-Congo (RDC) et dans une population de porcs vendus et abattus sur différents marchés de Kinshasa (RDC). Ce travail démontre aussi linfluence du commerce de la viande de porc infestée sur la transmission du parasite. En effet, alors quaucune différence significative nest observée entre les proportions de porcs infestés sur les des deux sites détude, lintensité de linfestation est significativement plus élevée chez les porcs des villages que chez les porcs des marchés. Il semble ainsi que les animaux hautement infestés sont exclus à un certain stade de la filière de production et de commercialisation de la viande de porc. Des enquêtes préliminaires réalisées auprès des éleveurs de porcs et des vendeurs de viande de porc indiquent que les éleveurs et/ou les acheteurs de porcs sélectionnent les animaux faiblement infestés et excluent les animaux positifs au langueyage (inspection de la langue) dans les villages. Les porcs hautement infestés sont, par conséquent, consommés par les villageois ou vendus sur des marchés clandestins. Linfluence possible de la filière de la production et de la commercialisation de la viande porcine sur la prévalence apparente de la CC observée dans cette étude devrait être prise en considération lorsque lon évalue limpact de la maladie sur la santé et la production animale. Des estimations précises de cet impact permettront la mise en place de mesures de contrôle et de prévention adéquates de la CC et de la taeniose. 4. Estimation des performances doutils sérologiques pour le diagnostic de la cysticercose humaine dans le cadre dune étude épidémiologique La dernière section expérimentale de cette thèse vise lutilisation de modèles bayésiens pour lestimation de la prévalence réelle dinfestation par et dexposition à T. solium, et des caractéristiques (sensibilité et spécificité) de trois tests sérologiques, à savoir , un ELISA pour la détection dantigènes circulants de cysticerques de T. solium (B158/B60 Ag-ELISA), un autre test immuno-enzymatique (« enzyme-linked immunoelectrotransfer blot assay », EITB) pour la détection danticorps dirigés contre sept glycoprotéines spécifiques à T. solium, et un ELISA pour la détection danticorps dirigés contre le liquide vésiculaire brut de cysticerques (Ab-ELISA), appliqués dans le cadre dune étude épidémiologique (incluant des individus non infestés et infestés avec ou sans symptômes) dans une région endémique de lEquateur. Les performances de lEITB et du B158/B60 Ag-ELISA sont comparables à celles obtenues dans le cadre détudes cliniques. Cependant, cette étude démontre limportance dune définition claire de ce quest « un cas » lorsque lon sadonne à un tel exercice. En effet, la sensibilité et la spécificité de lEITB et du B158/B60 Ag-ELISA sont élevées lorsquil sagit destimer la prévalence dexposition à T. solium (proportion dindividus ayant été en contact avec le parasite durant lannée précédente, avec ou sans établissement de cysticerques et, avec ou sans présence concomitante de cysticerques vivants) et dinfestation par le parasite (proportion dindividus actuellement infestés par des cysticerques vivants), respectivement, mais chutent dans le cas contraire. En conclusion, vu quaucun test parfait nest disponible à ce jour pour le diagnostic de la CC humaine, cette étude propose un outil destimation de la prévalence réelle de la maladie. Cette estimation est essentielle pour lévaluation de limpact de la CC. CONCLUSIONS ET PERSPECTIVES Même si lOrganisation Mondiale de la Santé (OMS) a déjà dressé une carte de la distribution globale de la CC due à T. solium, les données concernant celle-ci restent limitées et incomplètes dans beaucoup de régions endémiques du globe. A travers une étude de la littérature et quatre sections expérimentales, cette thèse montre que limpact de la CC porcine et humaine peut être non négligeable. De plus, ce travail permet de décrire de façon quantitative le manque de connaissance sur la maladie et propose quelques outils permettant dy pallier. Le risque de mal interpréter ou dextrapoler à tort des données incomplètes existe. Il pourrait donc être légitime de rejeter toute estimation plus globale de limpact dune maladie qui serait basée sur ces données. Cependant, le manque de données ne devrait pas signifier « estimation impossible » mais devrait plutôt soulever la question suivante: « Comment pouvons-nous y pallier? ». Pour cela, deux approches sont envisageables : (1) une approche prospective visant à développer des techniques plus performantes pour le diagnostic de la taeniose et de la CC et à permettre la collecte de données standardisées dans différentes zones endémiques du monde ; (2) une approche rétrospective ayant pour but dutiliser les données existantes de manière innovatrice, cest-à-dire en utilisant par exemple des modèles de simulation, des modèles bayésiens ou l« élicitation dexpert ». En conclusion, de nouveaux outils diagnostiques et techniques destimation sont en développement et en cours de validation pour pallier au manque de connaissances, aux limitations des protocoles détudes de recherches scientifiques (incluant les restrictions financières, techniques et éthiques) et/ou aux limitations des tests diagnostiques mais, de considérables efforts devraient être fournis afin de mettre ces outils à la disposition des pays en voie de développement et de standardiser les protocoles de recherche pour permettre une estimation globale de limpact de la CC. Une fois disponible, cette estimation pourra aider les décideurs politiques et les bailleurs de fonds à fixer les priorités en termes de lois, services et recherche scientifiques en santé publique et santé publique vétérinaire.