Made available in DSpace on 2015-03-26T13:47:24Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1111599 bytes, checksum: 1d237896c865356f1238a4fc70aec751 (MD5) Previous issue date: 2014-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The taeniasis-cysticercosis complex is a disease of great importance to public and animal health, and human beings play an important role as the only definitive hosts that develop taeniasis. Cysticercosis can affect pigs, which are infected by the larva of Taenia solium, cattle, which are infected by the larva of Taenia saginata and, accidentally, humans, who can act as an intermediate hosts (T. solium), developing cysticercosis in their tissues, with neurocysticercosis being the most severe form of the disease. Despite the importance of taeniasis and cysticercosis to public health, animal health and economy in Brazil, the epidemiological reality of the occurrence of zoonoses is poorly understood. In the state of Minas Gerais, most of the data is obtained from official sanitary inspection agencies in slaughterhouses, and little information is based on field data from live animals. In order to assess the epidemiological situation of the taeniasis-cysticercosis complex in small and medium-sized farms in the municipalities of Iraí de Minas, Romaria, Grupiara and Douradoquara, located in the microregion of Patrocínio, in the Triangulo Mineiro region, this study addressed the occurrence of human taeniasis, bovine and porcine cysticercosis, and the main risk factors associated with transmission of parasitic forms of T. saginata and T. solium in the sampled farms. Thus, a cross-sectional epidemiological study was conducted with 68 farms located in rural areas of the four aforementioned municipalities, and these properties were georeferenced. Data collected consisted of 1002 bovine blood samples, 22 porcine blood samples, and stool samples from 119 members of the households and applied an epidemiological questionnaire. The serological diagnosis of animal cysticercosis was performed by screening using the indirect ELISA test, and the suspected cases underwent Immunoblot testing for confirmation purposes. Stool examination was performed by the simple sedimentation method (HPJ). This study found a prevalence of 4.5% of porcine cysticercosis and 4.69% of bovine cysticercosis in the farms of the rural area of the sampled municipalities between July and August 2013. No case of human taeniasis was disagnosed; however, other enteroparasitoses were diagnosed. This study evaluated the association between some risk factors and the prevalence of cases of bovine cysticercosis, in which the variables that were statistically significant were the profession of the person in charge of such farms, income and the water treatment in the farms. From the georeferencing of farms, which generated maps of the collected points and the points diagnosed with bovine cysticercosis. There was the possibility that the transmission of this parasite may occur from the rivers and tributaries that flow along the sampled municipalities from the hydrography of the region. This study identified the prevalence of taeniasis-cysticercosis complex in the sampled municipalities and the results will aid in the prevention and control of this zoonosis in the areas of occurrence. / O complexo teníase-cisticercose é uma doença de grande importância para a saúde pública e animal, no qual o ser humano desempenha importante papel como o único hospedeiro definitivo, desenvolvendo a teníase. A cisticercose pode acometer o suíno, que desenvolve a larva da Taenia solium, o bovino, que desenvolve a larva da Taenia saginata e, acidentalmente, o homem pode atuar como hospedeiro intermediário (T. solium), desenvolvendo a cisticercose em seus tecidos, sendo a neurocisticercose a forma mais grave. Apesar da importância da teníase e da cisticercose para a saúde pública, para a saúde animal e para economia, a realidade epidemiológica da ocorrência dessas zoonoses no Brasil é pouco conhecida. No estado de Minas Gerais a maioria dos dados é obtida dos serviços oficiais de Inspeção Sanitária nos matadouros- frigoríficos, sendo poucas as informações baseadas em dados de campo oriundos de animais vivos. Com o objetivo de avaliar a situação epidemiológica do complexo teníase-cisticercose em pequenas e médias propriedades rurais dos municípios de Iraí de Minas, Romaria, Grupiara e Douradoquara, situados na microrregião de Patrocínio, região do Triângulo Mineiro, se pesquisou a ocorrência da teníase humana, da cisticercose bovina e suína e os principais fatores de risco associados à transmissão das formas parasitárias T. saginata e T. solium nas propriedades amostradas. Dessa forma, foi realizado um estudo epidemiológico de corte transversal envolvendo as 68 propriedades localizadas nas zonas rurais dos quatro municípios, sendo essas propriedades georreferenciadas. Foram coletadas 1002 amostras de sangue bovino e 22 amostras de sangue suíno, 119 amostras de fezes dos integrantes das famílias residentes nas propriedades e aplicado um questionário epidemiológico. O diagnóstico sorológico da cisticercose animal foi realizado por triagem pelo teste ELISA indireto e os casos suspeitos foram submetidos ao Immunoblot para confirmação. O exame de fezes foi realizado pelo método de sedimentação simples. Este estudo revelou prevalência de 4,5% de cisticercose suína e de 4,69% de cisticercose bovina nas propriedades da zona rural dos municípios amostrados, no período de julho a agosto de 2013. Não foi diagnosticado nenhum caso de teníase humana, no entanto, outras enteroparasitoses foram diagnosticadas. Avaliou-se a associação entre alguns fatores de risco e a prevalência dos casos de cisticercose bovina, no qual as variáveis que se mostraram estatisticamente significantes foram profissão do responsável pela propriedade, renda familiar e tratamento da água da propriedade. A partir do georreferenciamento das propriedades, foram produzidos os mapas dos pontos coletados e dos pontos diagnosticados com cisticercose bovina. Observou-se a possibilidade da transmissão dessa parasitose ocorrer a partir dos rios e seus afluentes nos municípios amostrados a partir da hidrografia da região. O estudo permitiu a identificação da prevalência do complexo teníase-cisticercose nos municípios amostrados e os resultados permitirão auxiliar a prevenção e o controle dessa zoonose nas áreas de ocorrência.

Larvas de cisticercos de Taenia crassiceps foram deixadas em repouso em TRIS 9mM pH 7,2 com 1mM EDTA até 180 minutos, os sobrenadantes coletados e processados nos 30, 60, 120 e 180 minutos, dando origem aos antígenos de excreção e secreção (ES 30; ES 60; ES 120 e ES 180). A caracterização do antígeno de excreção e secreção de larvas de Taenia crassiceps foi feito por SDS-PAGE e imunoblot utilizando anticorpos monoclonais (AcMos) anti-T. crassiceps e anti-T. solium e anticorpos humanos. Os resultados mostraram que o rendimento do antígeno ES foi menor nos primeiros 30 minutos (0,4 µg) por larva quando comparado os demais ES (ES 60: 2,4 µg; ES 120: 2,9 µg; ES 180: 2,5 µg). O SDS-PAGE confirmou que no ES 30 há menos proteínas. No imunoblot, o ES 180 mostrou que 6 AcMos (anti-LV-Tcra; anti-ES-Tcra; anti-LV-Tso: A3; anti-T-Tso: B4, B11 e A6) reconheceram apenas as frações 18- e 14-kDa do antígeno ES 180. Os AcMos anti-E-Tso (B8) e anti-LV-Tso (B6) não reconheceram frações do antígeno ES 180. Anticorpos presentes em amostras humanas de pacientes com NC reconheceram as frações protéicas entre 94- a 30-kDa e as de 18- e 14-kDa. Utilizando antígeno ES 180 e amostras de soros de pacientes supostamente saudáveis (GC), foram identificadas proteínas acima de 30-kDa e somente uma amostra reconheceu a de 16- kDa, anômala em relação ao perfil 18- e 14-kDa. As amostras de soro de pacientes com outras parasitoses mostraram reatividade com frações ≥ de 30-kDa do ES 180 e o maior índice de reatividade foi com a proteína 71-KDa. Um total de 77%; 70%; 60% e 70% das amostras de pacientes com toxocaríase, esquistossomose mansônica, hidatidose e Chagas, respectivamente, reconheceram a fração 71-kDa do ES 180. O antígeno ES pode contribuir com futuros estudos abordando a complexa relação parasito hospedeiro na cisticercose e na produção de vacinas para o uso em suínos. / Cysticercus Larvae of Taenia crassiceps were maintained in TRIS 9mM pH 7,2 with 1mM EDTA for 180 minutes; the supernatant was collected and processed at 30; 60; 120 and 180 minutes, originating excretion-secretion antigens (ES 30; ES 60; ES 120 and ES 180). The characterization of the ES antigen was conducted through SDS-PAGE and immunoblot using anti-T. crassiceps and anti-T. solium monoclonal antibodies (AcMos) and human antibodies. The results showed that the production of ES antigen was lower in the first 30 min. (0,4 µg) compared with the others (ES 60: 2,4 µg; ES 120: 2,9 µg; ES 180: 2,5 µg). The SDS-PAGE confirmed that ES 30 presented less protein. By immunoblot,6 AcMos (anti-LV-Tcra; anti-ES-Tcra;anti-LV-Tso: A3; anti-T-Tso: B4, B11 and A6) have recognized only the 18- and 14-kDa fractions of the ES 180. The anti-E-Tso (B8) and the anti-LV-Tso (B6) AcMos did not recognize any fractions. Antibodies from human samples NC recognized the proteins from 94- to 30-kDa and from 18- and 14-kDa. Using serum samples of apparently healthy individuals (GC), the ES 180 antigen showed proteins > 30-kDa and one sample recognized the 16-kDa fraction, anomalous when compared to the 18- and 14-kDa fractions. The serum samples of subjects with other parasitoses showed reactivity ≥ 30-kDa, more frequently with 71-KDa protein. A total of 77%; 70%; 60% and 70% of the samples from subjects presenting toxocariasis, esquistossomose mansonic, hydatidosis and Chagas disease, respectively, recognized the 71-kDa fraction of ES 180. The ES antigen may contribute to further studies on the complex cysticercosis parasite/host relation as well as for the production of vaccines for swine.

A detecção de antígenos em amostras de líquido cefalorraquiano (LCR) de pacientes com neurocisticercose (NC) foi realizada empregando-se o teste ELISA com soros policlonais de coelhos imunizados com os antígenos total de Taenia solium (T-Tso), líquido vesicular de Taenia crassiceps (LV-Tcra) e peptídeos <30kDa de LV-Tcra. Os soros policlonais foram fracionados para a obtenção da fração IgG - IgG anti-Tso, IgG antiTcra e IgG anti-Tcra<30kDa. Também foi empregado o anticorpo monoclonal específico para o antígeno de excreção e secreção de Taenia crassiceps (ES-Tcra). A seleção dos clones foi realizada por ELISA empregando-se os antígenos T-Tso e LV-Tcra. Foram analisados diferentes grupos de amostras divididos em: grupo de pacientes com NC (grupo NC), incluindo pacientes em diferentes fases evolutivas da doença, grupo de pacientes \"suspeito\" de NC (grupo \"suspeito\" NC), grupo controle (grupo C) e grupo de outros patologias (grupo OP). No teste ELISA empregando-se as frações IgG anti-Tso, IgG anti-Tcra e IgG anti-Tcra<30kDa, a sensibilidade obtida foi de 70%, 82,5% e 95,8% e a especificidade de 82,5%, 98% e 100%, respectivamente nas amostras do grupo NC e grupo C. Nas amostras do grupo diferentes fases evolutivas da doença, não houve diferença significativa de reatividade entre as amostras com as frações empregadas. Para as 21 amostras do grupo NC - fase ativa da doença, com a fração IgG anti-Tcra e o anticorpo monoclonal anti-ES-Tcra, respectivamente, 13 e 16 amostras foram positivas para a pesquisa de antígenos. As amostras de LCR do grupo C não apresentaram reatividade com os anticorpos empregados nos ensaios. Também foram ensaiadas 68 amostras de LCR de pacientes com \"suspeita\" de NC. De acordo com as características citoprotéicas além da reatividade para a pesquisa de anticorpos anti-T solium, as amostras de LCR apresentaram, neste grupo, padrão de reatividade para a pesquisa de antígenos que variou também de acordo com a presença de anticorpos, além das alterações de proteína e/ou células, que as amostras apresentavam ou não. Frações de 14 e 18kDa foram identificadas pelo teste imunoblot somente nas amostras de LCR de pacientes com NC utilizando as frações IgG anti-Tso, IgG anti-Tcra e anticorpo monoclonal anti-ES-Tcra. O anticorpo monoclonal anti-ES-Tcra mostrou-se eficiente para a pesquisa de antígenos no teste de competição por ELISA nas amostras de LCR de pacientes com NC e o antígeno ES-Tcra. / Antigen detection in cerebrospinal fluid (CSF) samples of patients with neurocysticercosis (NC) was performed through ELISA test using rabbits polyclonal sera immune with total antigens of Taenia solium (T-Tso) cysticercus, vesicular liquid of Taenia crassiceps (VL-Tcra) and vesicular liquid peptides (VLP-Tcra<30kDa) cysticercus. The polyclonal sera were separated obtaining IgG-lgG anti-Tso, IgG anti-Tcra and IgG anti-Tcra<30kDa fractions. A specific monoclonal antibody was also applied for reaching the excretion and secretion antigen of the T. crassiceps (ES-Tcra) larvae culture. Clones selection was performed through Elisa test applying the T-Tso and VL-Tcra antigens. When IgG anti-Tso, IgG anti-Tcra and IgG anti-Tcra<30kDa fractions were applied in the ELISA test, the accuracy obtained was 70%, 82,5% and 95,8% and the specificity of 82,5%, 98% and 100%, respectively, in samples of both NC and C groups. In the samples of the group in different stages of the disease there was no significant difference on reactivity between the samples when the fractions were applied. For the 21 samples of the NC group - active stage of the disease with IgG anti-Tcra fraction and the anti-ES-Tcra monoclonal antibody respectively, 13 and 16 samples were positive for antigen analyses. The CSF samples of the C group did not present reactivity with the antibodies applied in the tests. Tests for 68 CSF samples of \"suspected\" NC group, were also conducted. According to the cytoproteic characteristics besides the reactivity for the anti-T. solium antibody study, the CSF samples of this group showed standard reactivity for antigen detection ranging also in accordance with the presence of antibodies and of the protein and/or cell alterations that the samples would or not present. Fractions of 14 and 18kDa were identified by immunoblot test only in the CSF samples of patients with NC using the IgG anti-Tso IgG anti-Tcra fractions and the anti-ES-Tcra monoclonal antibody. The anti-ES-Tcra monoclonal antibody has shown to be efficient for analyzing antigens by a comparing method of the ELISA test in CSF samples of patients with NC and the ES-Tcra antigen.

A detecção de antígenos em amostras de líquido cefalorraquiano (LCR) de pacientes com neurocisticercose (NC) foi realizada empregando-se o teste ELISA com soros policlonais de coelhos imunizados com os antígenos total de Taenia solium (T-Tso), líquido vesicular de Taenia crassiceps (LV-Tcra) e peptídeos <30kDa de LV-Tcra. Os soros policlonais foram fracionados para a obtenção da fração IgG - IgG anti-Tso, IgG antiTcra e IgG anti-Tcra<30kDa. Também foi empregado o anticorpo monoclonal específico para o antígeno de excreção e secreção de Taenia crassiceps (ES-Tcra). A seleção dos clones foi realizada por ELISA empregando-se os antígenos T-Tso e LV-Tcra. Foram analisados diferentes grupos de amostras divididos em: grupo de pacientes com NC (grupo NC), incluindo pacientes em diferentes fases evolutivas da doença, grupo de pacientes \"suspeito\" de NC (grupo \"suspeito\" NC), grupo controle (grupo C) e grupo de outros patologias (grupo OP). No teste ELISA empregando-se as frações IgG anti-Tso, IgG anti-Tcra e IgG anti-Tcra<30kDa, a sensibilidade obtida foi de 70%, 82,5% e 95,8% e a especificidade de 82,5%, 98% e 100%, respectivamente nas amostras do grupo NC e grupo C. Nas amostras do grupo diferentes fases evolutivas da doença, não houve diferença significativa de reatividade entre as amostras com as frações empregadas. Para as 21 amostras do grupo NC - fase ativa da doença, com a fração IgG anti-Tcra e o anticorpo monoclonal anti-ES-Tcra, respectivamente, 13 e 16 amostras foram positivas para a pesquisa de antígenos. As amostras de LCR do grupo C não apresentaram reatividade com os anticorpos empregados nos ensaios. Também foram ensaiadas 68 amostras de LCR de pacientes com \"suspeita\" de NC. De acordo com as características citoprotéicas além da reatividade para a pesquisa de anticorpos anti-T solium, as amostras de LCR apresentaram, neste grupo, padrão de reatividade para a pesquisa de antígenos que variou também de acordo com a presença de anticorpos, além das alterações de proteína e/ou células, que as amostras apresentavam ou não. Frações de 14 e 18kDa foram identificadas pelo teste imunoblot somente nas amostras de LCR de pacientes com NC utilizando as frações IgG anti-Tso, IgG anti-Tcra e anticorpo monoclonal anti-ES-Tcra. O anticorpo monoclonal anti-ES-Tcra mostrou-se eficiente para a pesquisa de antígenos no teste de competição por ELISA nas amostras de LCR de pacientes com NC e o antígeno ES-Tcra. / Antigen detection in cerebrospinal fluid (CSF) samples of patients with neurocysticercosis (NC) was performed through ELISA test using rabbits polyclonal sera immune with total antigens of Taenia solium (T-Tso) cysticercus, vesicular liquid of Taenia crassiceps (VL-Tcra) and vesicular liquid peptides (VLP-Tcra<30kDa) cysticercus. The polyclonal sera were separated obtaining IgG-lgG anti-Tso, IgG anti-Tcra and IgG anti-Tcra<30kDa fractions. A specific monoclonal antibody was also applied for reaching the excretion and secretion antigen of the T. crassiceps (ES-Tcra) larvae culture. Clones selection was performed through Elisa test applying the T-Tso and VL-Tcra antigens. When IgG anti-Tso, IgG anti-Tcra and IgG anti-Tcra<30kDa fractions were applied in the ELISA test, the accuracy obtained was 70%, 82,5% and 95,8% and the specificity of 82,5%, 98% and 100%, respectively, in samples of both NC and C groups. In the samples of the group in different stages of the disease there was no significant difference on reactivity between the samples when the fractions were applied. For the 21 samples of the NC group - active stage of the disease with IgG anti-Tcra fraction and the anti-ES-Tcra monoclonal antibody respectively, 13 and 16 samples were positive for antigen analyses. The CSF samples of the C group did not present reactivity with the antibodies applied in the tests. Tests for 68 CSF samples of \"suspected\" NC group, were also conducted. According to the cytoproteic characteristics besides the reactivity for the anti-T. solium antibody study, the CSF samples of this group showed standard reactivity for antigen detection ranging also in accordance with the presence of antibodies and of the protein and/or cell alterations that the samples would or not present. Fractions of 14 and 18kDa were identified by immunoblot test only in the CSF samples of patients with NC using the IgG anti-Tso IgG anti-Tcra fractions and the anti-ES-Tcra monoclonal antibody. The anti-ES-Tcra monoclonal antibody has shown to be efficient for analyzing antigens by a comparing method of the ELISA test in CSF samples of patients with NC and the ES-Tcra antigen.

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.

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%).