M.Sc. (Zoology) / A literature survey revealed gaps in the knowledge on Ergasilus in Africa. This studied aimed to elucidate on some of these matters. Ergasilus sarsi was collected from Lamprichthys tanganicanus during an expedition to Lake Tanganyika in March 2010. The gills of the fish were removed and preserved for further studies. Preserved specimens were studied with dissection- and light microscopy. Some specimens were also studied with a scanning electron microscope (SEM). For light microscopy the specimens were sectioned and then stained with AZAN and H&E. A total of 32 Lamprichthys tanganicanus were collected and studied for ergasilids. The prevalence was 86.40%, the mean intensity 7.56 and the mean abundance 6.38. A total of 204 parasites were collected and only 27 hosts were infected. The highest intensity was 29 parasites. Pearson’s Chi-squared test was used to compare attachment preferences of Ergasilus sarsi. The parasite exhibited site selection but not host specificity. It was noticed that E. sarsi mostly attach to the tip of the gill filament of the second gill arch. The second gill arch receives the largest portion of water flow supporting distribution of newly hatch ergasilid nauplius. There was no significant preference for the dorsal, medial and ventral attachment sites (p-value = 0.000542). However, significant preference between distal, central and proximal regions (p-value = 1.19) was observed. Fryer (1965) observed that the pathology caused by ergasilids is related to their attachment position on the host. Ergasilids display variation regarding morphology of their second antennae. Some have spines and others elongated antennae that wraps around the entire gill filament. This study shows that Ergasilus sarsi (with no spines on the second antennae) wraps around the gill filament and cause considerable damage to the host. The entire gill filament structure changed due to lamellar fusion and proliferation of mucous – and epithelial cells. Comparison of an infected gill to a healthy gill revealed differences. The compression caused by the second antennae caused some blood vessels to rupture resulting in haemorrhage. The swimming legs of the parasite also cause considerable damage by scraping gill tissue off the host and pushing it towards the mouth parts of the parasite. Mucous cells, gill epithelium and blood cells were observed in the vicinity of the mouth and in the intestine of the parasite. An increase in the number of Rodlet cells and mast cells were also observed on the gills in close proximity to the parasite. Increase in the number of these cells clearly indicate an inflammatory response. This is the first record of Ergasilus sarsi on Lamprichthys tanganicanus. This study also provides the first detailed description of the pathology caused by Ergasilus sarsi as well as the attachment distribution of this parasite.

Orientador: Reinaldo José Silva / Resumo: Trematódeos do gênero Synthesium infectam o intestino de diversas famílias de odontocetos em todo o mundo. No entanto, a identificação e o status taxonômico de Synthesium ainda são confusos e, principalmente, baseados em análises morfológicas. As informações genéticas ainda são excassas. O presente estudo teve como objetivo investigar a diversidade de parasitos intestinais do gênero Synthesium colhidos de diferentes odontocetos, através de comparações morfológicas e moleculares. Foram estudados parasitos de golfinhos encontrados mortos em praias ou acidentalmente capturados em redes de pesca de diferentes regiões. Durante a necropsia, o intestino delgado foi removido e armazenado a -20°C. Posteriormente, os intestinos foram abertos, lavados em água corrente sobre peneira de 150 μm e o conteúdo examinado sob estereomicroscópio. Os trematódeos encontrados foram fixados e preservados em etanol 70% para análises morfológicas e moleculares. Os trematódeos foram preparados em lâminas temporárias e as análises morfométricas diagnósticas foram feitas em um sistema computadorizado para análise de imagens. O DNA genômico dos trematódeos foi extraído e amplificado utilizando-se primers com alvo no DNA ribossomal (menor subunidade do DNA ribossomal - gene SSU - e região intergênica - ITS1) e DNA mitocondrial (nicotinamida dinucleotídeo dehidrogenase subunidade 3 - gene ND3 - e citocromo c oxidase subunidade I - gene COI). Os resultados morfológicos e moleculares apontam a existência de p... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

L'élevage de petits ruminants est majoritairement représenté dans les pays tropicaux et subtropicaux. Le parasitisme par des nématodes gastro-intestinaux (NGI), transmis via le pâturage, est une des principales causes de pertes de production en ovins comme en caprins. Depuis le milieu du XXème siècle, la généralisation de l'emploi des anthelminthiques s'est accompagnée d'une augmentation marquée de la productivité. Cependant, la sélection et la diffusion progressive de souches parasitaires résistant aux anthelminthiques rendent cette méthode de contrôle de moins en moins efficace. Ainsi, une enquête récente en Guadeloupe montre que 100% des populations de NGI sont résistantes aux benzimidazoles et que la majorité l'est à plusieurs familles d'anthelminthiques. Nous développons, à partir des connaissances acquises sur l'épidémiologie des NGI et sur les relations entre hôtes et parasites, des systèmes de contrôle intégré des parasites. Le premier élément en est l'utilisation de méthodes de traitement ciblé, à l'échelle de l'élevage entier. Ainsi, la méthode Famacha nous a permis, en constituant un refuge estimé à 50 à 80% des NGI, de réduire le risque de sélection de NGI résistants sans pénaliser la production. Les autres éléments ont pour objectif de diminuer le niveau global d'infestation du troupeau, en combinant des méthodes visant à renforcer les capacités de défense des animaux (alimentation adaptée, amélioration génétique…) et à diminuer le risque de rencontre hôte – parasite (gestion du pâturage, association d'espèces d'herbivores, utilisation des métabolites secondaires des plantes…). Le choix des différents éléments de contrôle intégré des NGI devra se baser sur leur faisabilité, en termes d'investissements matériels et humains, sur leur compatibilité avec le système d'élevage, et sur leur efficacité. Les développements futurs devront permettre d'évaluer les interactions entre ces éléments afin de pouvoir optimiser les choix des éleveurs / Most of the sheep and goats are reared in tropical and subtropical countries. Gastrointestinal nematode parasites (GIN), which are transmitted through the pastures, are among the main causes of production losses for small ruminant farmers. Since the 1940's the pharmaceutical industry has provided very efficient anthelmintics which allowed easy to run and profitable worm control. Unfortunately the systematic use of anthelmintics has resulted, within few years, in an increasing number of anthelmintic resistant (AR) nematode strains. As example, a survey in Guadeloupe (F. W. I.) revealed that all goat farms have to face at least resistances to benzimidazoles, and most of them must deal with resistances to 2 or 3 drug families. We are building up integrated systems to manage GIN infection, by seeking to slow down the spreading of AR strains of GIN and to reduce anthelmintic dependency. Firstly we propose targeted selective treatment methods (or any method allowing the survival of untreated GIN in refugia) and secondly a panel of methods to reinforce host defences (mainly through nutrition and genetic improvement) and to decrease the probability of host-parasite encounter through grazing man-agement, association of herbivore species with different specific parasites, use of plant secondary metabolites with anthelmintic properties... The choice of methods to be combined must be based on their feasibility in terms of human and material resources, compatibility with the farming system and effi-ciency. Future developments would address the evaluation of interactions between components of GIN integrated systems of management, in order to optimize the farmer choices

O litoral brasileiro apresenta a ocorrência de cinco das sete espécies de tartarugas marinhas presentes no mundo. A região da costa sudeste brasileira é uma área de alimentação de tartarugas verdes juvenis. Muitas ameaças; a grande maioria delas por ação antrópica estão diminuindo as populações de tartarugas marinhas, mas também causas naturais podem estar envolvidas. O presente trabalho tem por objetivo descrever os principais achados necroscópicos e histopatológicos de tartarugas verdes achadas mortas, ou que morreram no centro de reabilitação do Projeto Tamar na cidade de Ubatuba/SP. Como resultados, relações estatísticas foram encontradas entre achados macroscópicos e formas de captura, além de observar grande quantidade de animais acometidos pela presença de parasitas da família Spirorchiidae e suas lesões. Além disso, foi constatada a evidência de resíduos antropogênicos relacionados a presença de fezes compactas associadas a constipações ou obliterações no trato gastrointestinal. Algumas lesões sugestivas de infeções por agentes bacterianos também foram observadas, mas em menor proporção. Foi realizada a dosagem da concentração de cálcio e magnésio no líquido pericárdico, demonstrando maior concentração destes eletrólitos em animais achados mortos - presos em rede de pesca. Os resultados obtidos neste estudo podem representar uma ajuda para o clínico e determinar a presença de possíveis doenças emergentes nestas populações. / Five of the seven sea turtle species in the world gather into Brazilian coastline. The region of the southeast Brazilian coast is a feeding area for young green turtles. There are many threats, the vast majority of them are decreasing populations of sea turtles by anthropic action, but natural causes may also be involved. The present work had as purpose to describe the main necroscopic and histopathological findings in green turtles that were found dead or that were found dead at the rehabilitation center of Tamar Project in Ubatuba City/SP. As results, statistical relationships were found among macroscopic findings and catching methods, beside the observation of high quantity of animals stricken by the presence of Spirorchiidae family parasites and their lesions. In addition, the evidence of anthropogenic residues related to the presence of compact feces associated with constipation or gastrointestinal obliterations was verified. Some lesions suggests infections by bacterial agents were also observed, but in a small proportion. The dosage of calcium and magnesium in the pericardial fluid was determined, evidencing a higher concentration of these electrolytes in animals found dead trapped in fishing net. The results obtained in this study may represent a support for clinicians and it may determine the presence of possible emerging diseases in these populations.

Atualmente, milhões de pessoas, por todo o globo, estão sob risco de serem infectados por um protozoário transmitido vetorialmente por pequenos insetos flebotomíneos. Este parasita é a Leishmania spp., causadora de uma patologia de amplo espectro, que varia desde a moléstia cutânea (tegumentar) até a visceral (kala-azar). A leishmaniose cutânea é a manifestação clínica de maior ocorrência (mais de 90% dos casos). A radiação ionizante, gerada em fonte de 60Co, tem sido utilizada com sucesso para promover alterações físico-químicas em diferentes protozoários, incluindo a Leishmania spp. Em trabalhos anteriores determinou-se que formas promastigotas de Leishmania amazonensis, irradiadas com diferentes doses de radiação gama, perdem sua viabilidade mantendo, porém, sua imunogenicidade. No presente trabalho, estudouse a utilização da radiação ionizante como ferramenta na seleção de formas metacíclicas do parasita em cultura axênica para a possível produção de imunógenos irradiados mais eficientes. Os resultados demonstram que culturas irradiadas com 400 Gy de radiação gama, possuem uma concentração de aproximadamente 75% de parasitas metacíclicos, capazes de produzir, in vitro, uma infecção que mimetiza a ocorrida naturalmente. Estes parasitas irradiados têm sua estrutura celular interna modificada mantendo, entretanto, seu arcabouço externo intacto. Camundongos de uma linhagem suscetível imunizados com leishmanias irradiadas com diferentes doses tiveram sua produção de imunoglobulinas aumentada, e mantiveram os títulos elevados após o desafio com parasitas não irradiados. Em outras linhagens pesquisadas este padrão se manteve, porém em títulos menores, sendo que camundongos imunodeficientes não responderam à imunização nem ao desafio. / Actually, millions of people around the globe are under the risk of infection by a protozoan transmitted by a bit of a sand fly. This parasite is a Leishmania spp. This causes a wide spectrum disease, since a coetaneous disease to a visceral one. The coetaneous form is the major clinical manifestation (above 90%). The ionizing radiation, produced in a 60Co font, had being successes used to promote physical-chemical transformations on different protozoans, including Leishmania spp. In previous work was determined that promastigotes forms of Leishmania amazonensis, irradiated with different doses of radiation, lost their viability maintaining, however, their immunogenicity. In this work, was studied the use of ionizing radiation as a tool for selection of metaciclic forms of the parasite in axenic culture, for a possible efficient irradiated immunogen production. Our results shown that cultures irradiated with 400 Gy of gamma irradiation, has 75% of metaciclic form, which are capable to produce, in vitro, an infection that is similar the natural occurrence. These irradiated parasites have their internal cellular structure modified, maintaining their external structure intact. Susceptible strain of mice immunized with leishmania irradiated with different doses had high immunoglobulin production, and maintained this production after the challenge with naive parasites. In other strains this default was similar, however in lower titles. Immunodeficient mice didnt produce immunoglobulin nor on the immunization or on the challenge.

A diarréia em bezerros é comprovadamente uma das principais causas de perdas econômicas em rebanhos de corte, sendo os prejuízos diretamente derivados da redução do ganho de peso e custos com tratamento. Considerando-se que, para o delineamento de medidas profiláticas adequadas ao controle de uma doença é necessário o conhecimento de suas causas, o presente trabalho teve por objetivo estudar de modo longitudinal a freqüência de ocorrência de coronavírus bovino (BCoV), rotavírus do grupo A (RV-A), protozoários, helmintos e enterobactérias em uma propriedade com casos esporádicos e em outra com casos recorrentes de diarréia em bezerros. Investigou-se, ainda, a presença de genes codificadores de para as toxinas shiga-like 1 e 2 , para as adesinas K99 e F41 e para a intimina (eae) nas E. coli isoladas. Para a detecção de BCoV, utilizou-se uma nested-RT-PCR direcionada ao gene codificador da RNA polimerase RNA dependente, e para a detecção de RV-A utilizou-se ELISA direto duplo sanduíche. O isolamento e caracterização bioquímica das colônias de bactérias foram conduzidos de acordo com técnicas de bacteriologia clássica. A caracterização genotípica das colônias de E. coli isoladas foi realizada através de uma Multiplex-PCR, utilizando primers para os genes codificadores dos seguintes fatores de virulência: Stx1, Stx2, Sta, K99, F41 e eae. A detecção de parasitas foi realizada por centrífugo sedimentação em água-eter e centrífugo-flutuação em solução supersaturada de sacarose, considerando-se como resultado final do exame coproparasitológico todos os parasitas encontrados em ambas as técnicas em sua maior contagem. A freqüência de ocorrência de coronavírus bovino e rotavírus do grupo A foi baixa, restrita a animais com até quatro meses de idade, enquanto que protozoários, helmintos e enterobactérias apresentaram tendência crescente em freqüência relacionada à progressão da idade dos animais. Foram identificados os patotipos STEC, AEEC e um padrão atípico com os genes de K99 e eae. Além disso, encontrou-se associação entre baixo padrão sanitário e maior freqüência de ocorrência de Eimeria spp, Strongyloidea, Strongyloides spp, Trichuris spp e Escherichia coli portadora de fatores de virulência Stx1, Stx2, K99 e eae. O presente trabalho colabora para a caracterização da microbiota entérica de bezerros, mas mantém abertas as questões relativas às diferenças específicas entre as biotas entéricas de bezerros sadios e com diarréia, enfatizando a importância de se realizarem mais estudos que investiguem simultaneamente diversos enteropatógenos potenciais nestes animais / Diarrhea in calves is proved to be one of the main causes of economic loss in beef herds, which is direct originated by reduction of weight gain and increment of treatment costs. It is known that the determination of appropriate preventive measures to control a disease depends on the knowledge of its causes. In this manner, the present work aimed to study longitudinally the frequency of occurrence of bovine coronavirus (BCoV), group A rotavirus (RV-A), protozoa, helminths and enterobacteria in a beef farm presenting sporadic cases and other with recurrent cases of diarrhea. Moreover, the presence of genes that express the following virulence factors were investigated in the isolated E. coli: shiga-like toxins 1 and 2, adhesins K99 and F41 and intimin (eae). A nested-RT-PCR targeted to the RNA-dependent RNA polimerase gene was conducted to detect BCoV, and a double-sandwich direct ELISA was used to detect RV-A. Classical bacteriology techniques were used to isolate and indentify bacterial colonies. A Multiplex-PCR, with primers designed to previously described E. coli genes, was used to genotype these colonies. Centrifuge sedimentation in water-ether and centrifuge flotation in sucrose supersaturated solution were used to detect the presence of parasites. The final result was achieved by the highest count of all the parasites found. The observed frequency of occurrence of both BCoV and RV-A was low and restricted to animals up to 4 months of age whereas protozoa, helminths and enterobacteria showed an increasing tendency on its frequency related to progression of animals aging. STEC, AEEC and an atypical pathotype of E. coli, with K99 and eae genes were found. Moreover, an association between low sanitary pattern and a higher frequency of Eimeria spp, Strongyloidea, Strongyloides spp, Trichuris spp and Escherichia coli bearing Stx1, Stx2, K99 and eae genes was observed. The present study contributes to the characterization of calf enteric microbiota. However, the points related to the specific differences between healthy and diarrheic calves enteric microbiota remain unclear, emphasizing the importance of future studies to investigate different potential enteropathogens in beef calves simultaneously

Introdução: Na prática dos serviços de saúde, observa-se que as enteroparasitoses ocupam um importante papel no dia a dia das famílias e são mais frequentes em áreas urbanas cujo nível socioeconômico é reduzido. No Brasil, estudos indicam que, em algumas regiões, a prevalência de enteroparasitoses em crianças chega a acometer 61% da população. A área escolhida para o estudo abrange bairros de periferia do município de Ribeirão Preto, sendo estes: Maria Casagrande Lopes, Conjunto Habitacional Alexandre Balbo, Loteamento Jardim Orestes Lopes e Parque dos Pinus, cuja população é atendida pela Unidade Básica de Saúde Maria Casagrande Lopes, Ribeirão Preto-SP. A escolha do tema desta pesquisa teve por justificativa a gravidade das enteroparasitoses na primeira infância, as barreiras socioeconômicas e culturais da população em estudo e os escassos estudos sobre a situação atual das enteroparasitoses na comunidade do município do estudo. Objetivos: determinar a prevalência e possíveis associações desta com os fatores socioeconômicos, demográficos, fatores de risco e as condições de saúde de uma população de 962 crianças de três a 12 anos, na área de abrangência de uma UBS no município de Ribeirão Preto-SP. Materiais e Métodos: trata-se de um estudo epidemiológico, de delineamento transversal, com população amostral de 462 crianças, nas quais se realizou exame de fezes para determinar a razão da prevalência de enteroparasitas. Além disso, aplicou-se um questionário aos responsáveis das crianças, abordando questões que permitissem a realização de associações de prevalência de enteroparasitas com as variáveis: escolaridade da mãe, renda familiar, idade, sexo e tipo de água consumida no domicílio. Para a análise dos dados foi utilizado o programa SPSS 10.0 e Ri3863.0.0, sendo aplicados os testes Qui quadrado e Fisher, com nível de significância de p<0,05. O projeto obteve aprovação do Comitê de Ética da EERP em 16/02/2011 (nº1252/2011). Resultados: os resultados evidenciaram que a prevalência de enteroparasitas foi alta (57,5%), sendo 54,4% no sexo feminino e 60,9% no sexo masculino. Giardia lamblia foi o parasita mais prevalente entre as crianças infectadas (50,8%), seguido de Ascaris lumbricoides (17,8%), Entamoeba histolytica, Hymenolepis nana, Entamoeba coli e Enterobius vermiculares (5,6-7,3%) e outros parasitas com frequências menores. Das amostras positivas, 64,9% apresentaram monoparasitismo, 27,6%, biparasitismo e 7,5%, poliparasitismo. Não houve associação estatisticamente significativa entre a prevalência e os fatores de risco analisados. Apesar disso, constatou-se que 67,2% da amostra populacional da área estudada consumia água diretamente da torneira, e 49,9% dos responsáveis lavavam as frutas e verduras somente com água. Todas as crianças parasitadas foram medicadas, e foi realizada uma atividade educativa com os familiares. Conclusão: apesar de a área de abrangência do estudo apresentar mínimas condições socioeconômicas e demográficas, isto é, maioria das famílias ter renda maior que um salário-mínimo, bairros com 100% de coleta de lixo, 99,7% de cobertura de energia elétrica, presença de apenas uma residência com fossa séptica e a maioria das mães ter escolaridade até o ensino médio, dentre outros; detectou-se elevada prevalência de enteroparasitas nas crianças. Esses achados sugerem a necessidade da implementação de ações com enfoque na promoção de saúde para essa população / Introduction: it is observed in the practice of health services that enteroparasitosis play an important role in the daily lives of families and are more common in urban areas whose socioeconomic status is low. In Brazil, studies indicate that in some regions the occurrence of enteroparasitosis in children affects 61% of the population. The area chosen for the study covers the suburban neighborhoods namely: Maria Casagrande Lopes, Conjunto Habitacional Alexandre Balbo, Loteamento Jardim Orestes Lopes and Parque dos Pinus, whose population is assisted by Maria Casagrande Lopes Basic Health Unit, in the city of Ribeirão Preto-SP. The theme of this research was chosen because of the severity of enteroparasitosis in early childhood, the socioeconomic and cultural barriers of study population and the few studies on the current status of enteroparasitosis in communities of the studied city. Objectives: to determine the prevalence and possible associations of enteroparasitosis with socioeconomic, demographic and risk factors and health conditions of a population of 962 children aged from three to twelve years old in an area covered by a family health unit in the city of Ribeirão Preto. Materials and Methods: this is an epidemiological and cross-sectional study, with population sample of 462 children in whom fecal exam was performed to determine the reason for the prevalence of intestinal parasites. Additionally, a questionnaire was applied to the person responsible for the children, addressing questions to perform associations between the prevalence of intestinal parasites and the variables: mother\'s education, family income, age, gender and type of water consumed at home. Data analysis used the SPSS 10.0 and Ri3863.0.0, being applied the chi-square and Fisher tests, with a significance level of p<0.05. The Research Ethics Committee of the University of São Paulo at Ribeirão Preto College of Nursing approved the project in February 2011 (protocol number 1252/2011). Results: the results showed that the prevalence of intestinal parasites was high (57.5%), being 54.4% females and 60.9% males. Giardia lamblia was the most prevalent parasite (50.8%), followed by Ascaris lumbricoides (17.8%), Entamoeba histolytica, H. nana, E. coli and Enterobius vermicularis (5.6-7.3%) and other parasites with much lower frequencies. Related to the positive samples, 64.9% had monoparasitism, 27.6% biparasitism and 7.5% poliparasitism. There was no statistically significant association between the prevalence and risk factors analyzed. Nevertheless, it was found that 67.2% of the sample of the study area consumed water directly from the tap and 49.9% of parents wash their fruits and vegetables with water only. All parasitized children were medicated and an educational activity with the family members was performed. Conclusion: although the area covered by the study have good socioeconomic and demographic conditions, that is, most families have higher income than minimum wage, neighborhoods with 100% garbage collection, 99.7% coverage of electricity, only one residence with septic tank and most mothers with high school education, among others; it was found a high prevalence of intestinal parasites in children. These findings suggest the need to implement actions with a focus on health promotion for this population

Biological rhythms are thought to have evolved to enable organisms to organise their activities according to the Earth’s predictable cycles, but quantifying the fitness advantages of rhythms is challenging and data revealing their costs and benefits are scarce. More difficult still is explaining why parasites that exclusively live within the bodies of other organisms have biological rhythms. Rhythms exist in the development and traits of parasites, in host immune responses, and in disease susceptibility. This raises the possibility that timing matters for how hosts and parasites interact and, consequently, for the severity and transmission of diseases. Despite their obvious importance in other fields, circadian rhythms are a neglected aspect of ecology and evolutionary biology. The ambitions of this thesis are to integrate chronobiology, parasitology and evolutionary theory with mathematical models to obtain a greater understanding about how and suggest why malaria parasites have rhythms as well as the effect of infection on host rhythms. First, I identify how malaria parasites lose their developmental rhythms in culture, when they lack any potential time cues from the host. Next, I characterise parasite rhythms inside the mammalian host in terms of synchrony and timing and demonstrate there is genotype by environment interactions for characteristics of parasite rhythms. Then, I investigate the effect that parasite infection has on host rhythms and show there is variation between parasite genotypes in their effect on host locomotor activity and body temperature rhythms during infections. Finally, I explore which host rhythms may be driving parasite synchrony and timing and demonstrate the importance of peripheral host rhythms for the timing of malaria parasite developmental rhythms. The data presented here provides novel and important information on the role of rhythms during disease and opens up a new arena for studying host-parasite coevolution.

Made available in DSpace on 2014-06-11T19:22:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-04-18Bitstream added on 2014-06-13T18:08:05Z : No. of bitstreams: 1 garcia_jgd_me_arafcf.pdf: 502931 bytes, checksum: f5e5c5673828eed8be4251d55efd74a7 (MD5) / Universidade Estadual Paulista (UNESP) / O protozoário Giardia lamblia foi escolhido como tema de estudo, por ser um enteroparasita de prevalência significativa no mundo inteiro. Os objetivos desta pesquisa foram estudar a reprodutibilidade diagnóstica dos métodos Direto, Faust e cols., COPROTEST e Hematoxilina Férrica, bem como descrever a presença da Giardia lamblia, segundo a associação com algumas características da população de estudo como: grupo etário, gênero e distribuição dos casos segundo a variação sazonal nos meses em que se desenvolveu a pesquisa. Foram analisadas 200 amostras de fezes de crianças da região de Araraquara-SP e como resultados encontrou-se Giardia lamblia como o parasita mais freqüente, com 8,0%, não houve associação com o gênero; quanto à idade ocorreram mais casos no grupo de 03 a 05 anos e a maior freqüência de casos foi no mês de janeiro. Em relação as metodologias utilizadas chegou-se a conclusão que o melhor método diagnóstico para Giardia lamblia seria a associação de pelo menos, duas metodologias associadas de ótima reprodutibilidade que nesse estudo foram: COPROTEST - Faust; Direto-Faust e Coprotest-Direto (k > 0,81). / Giardia lamblia protozoan was chosen as a study them due to its significant prevalence all over the world. The present dissertation aims to study the diagnostic reproductibility of Direct, Faust et al., COPROTEST and Ferric Hematoxiline methods. It also describes the presence of Giardia lamblia, according to the association with some characteristics of the population in study, such as group age, gender and distribution of cases according to seasonal variation in the month studied. 200 feces samples of children from the region of Araraquara-SP were analysed and to cach of them the four diagnostic methodolgies were applied and then compared. From the results obtained it was possible to conclude that Giardia lamblia was the most frequent parasite, with 8, 0% occurrence; there was no association with gender; most cases of parasites were found in the 3-5 year-old groups, the highest frequency of parasites occurred in january and the best diagnostic to detect Giardia lamblia was the association of at least two methodologies of optimum reproductibility. The associations of optimum reproductibility were COPROTEST- Faust, Direct- Faust and COPROTEST- Direct (k >0, 81).

This thesis aimed to understand the mechanisms underlying within-host interactions among coinfecting parasites in wild rodents, how they are affected by the host immune response, and how they contribute to shape disease dynamics in nature. Coinfection is ubiquitous in human, domestic and wild animal populations, and can consist of both microparasites (viruses, bacteria and protozoa) and macroparasites (parasitic helminths). Moreover, coinfecting parasites can interact with each other in a number of ways (positive or negative, direct or indirect), which affects disease severity and progression, parasite transmission, the response of target and non-target parasites to treatment and, ultimately, the epidemiology of each coinfecting parasite species. While previous work on laboratory animals has generated detailed knowledge of the cellular components of the host immune response involved during coinfection, we still mostly lack a conceptual understanding of the role of the host immune response in mediating within-host interactions in nature. I used a known within-host interaction between two important intestinal parasites (the nematode Heligmosomoides polygyrus and the protozoan Eimeria hungaryensis) of wild wood mice (Apodemus sylvaticus) to study the underlying causes and consequences of this interaction for both parasite dynamics and host health. I first investigated if specific and total antibody levels can explain natural burdens and infection of H. polygyrus and Eimeria spp. in the context of other parasites and variation in host demography in a cross-sectional field study. I found that H. polygyrus-specific IgG1 and total faecal IgA were the strongest predictors of both H. polygyrus infection and burden and Eimeria spp. infection. Further, Eimeria spp. infection was associated with lower antibody levels, suggesting an interaction between Eimeria spp. and anti-helminth immunity. Next, I tested the causative relationship between antibody levels and parasite infection. Over the course of a longitudinal anthelmintic treatment study in the field, I measured infection and burden of both target and non-target parasites, as wells as specific and general antibody levels. I found that treatment successfully reduced H. polygyrus burden, wild led to a change in both antibody levels and E. hungaryensis dynamics. Further, H. polygyrus-specific IgG1 levels were predicted by pre-treatment H. polygyrus burden, suggesting that helminth infection induces antibody production, rather than vice versa. Following from this, I explored if treatment of single or multiple parasite groups (helminths, coccidia or both) had an effect on host survival. I used data from a longitudinal field study spanning an entire season of A. sylvaticus (April-December), where animals were given either Ivermectin (anthelmintic), Vecoxan (anti-coccidial), a mix of both drugs or water every fortnight. Ivermectin treatment led to a consistent reduction in H. polygyrus prevalence and burden, as well as a steady increase in E. hungaryensis prevalence, whereas Vecoxan treatment failed to show any effect on either target or non-target parasites. Interestingly, anthelmintic treatment led to a reduction in survival at intermediate H. polygyrus burdens, suggesting that anti-parasite treatments might not always be beneficial for the host. By bringing this wild coinfection system into the lab, I examined if the interaction between H. polygyrus and E. hungaryensis could be re-created under controlled laboratory condition, and if the lack of environmental variation had an effect on parasite and/or antibody dynamics. I found that coinfection led to a delay in H. polygyrus expulsion, and decreased E. hungaryensis shedding during chronic helminth infection. However, coinfection did not affect antibody dynamics. This not only demonstrated that the interaction between the two parasites was reciprocal, but also showed that coinfection can significantly affect parasite transmission dynamics. In an ongoing bioinformatic analysis, I investigated the level of genetic diversity in wild Eimeria spp. populations in order to uncover the mechanism underlying a common lack of protective immunity towards Eimeria spp. infections in wild and domestic animal populations. I found that there were multiple genetically distinct strains circulating within all populations tested, but homologous re-infection was not less likely than heterologous reinfection. This suggests that the lack of protective immunity in wild Eimeria spp. Populations cannot solely be explained by high levels of genetic diversity. This thesis provides several important insights into the mechanisms underlying parasite within-host interactions. Importantly, it highlights that, whilst host immunity plays a crucial role in determining the outcome of coinfection, other factors such as host demography have to be taken into account in order to understand the interplay between immunity and coinfection. I further show that anti-parasite treatments in the wild can be successful, but the benefits of such treatments can be context dependent. More broadly, my findings can have important implications for the planning and evaluation of treatment programs targeted at both single and coinfected animals and humans in their natural environment.