Esgotos urbanos constituem compartimentos ambientais que favorecem a emergência e re-emergência enfermidades de veiculação hídrica. Este estudo objetivou analisar cistos de Giardia spp., oocistos de Cryptosporidium spp., assim como cistos, ovos e larvas de outros protozoários e helmintos patogênicos; Coliformes Totais e Termotolerantes, Rotavírus e Adenovírus em amostras de esgoto bruto e tratado da Estação de Tratamento de Esgoto de Ribeirão Preto - SP. As coletas de esgoto foram realizadas no ponto de entrada e no ponto de saída da ETE-Ribeirão Preto/SP. As análises de cistos de Giardia spp. e oocistos de Cryptosporidium spp. foram realizados pelo Método 1623 da EPA. Ovos, cistos e larvas de outros protozoários e helmintos foram analisados pelo Método de Sedimentação proposto pela CETESB (1989). A análise de coliformes totais e termotolerantes foi realizada pela Técnica de Tubos Múltiplos (Colilert®). A análise de vírus foi realizada através do Teste de Elisa com o KIT da RIDASCREEN® Enzimaimunoensaio. Os resultados obtidos revelaram que a concentração de Giardia spp. no esgoto bruto variou de 120 a 2200 cistos/L, já no esgoto tratado essa concentração variou de 0,45 a 3,5 cistos/L. Com relação aos oocistos de Cryptosporidium spp. a concentração no esgoto bruto variou de não detectável a 28,9 oocistos/L e no esgoto tratado as concentrações variaram de não detectável a 1,05 oocistos/L. O processo de lodos ativados na ETE-RP promoveu uma remoção parcial de parasitas, tais como: Endolimax nana, Entamoeba coli, Entamoeba hystolitica, Ancylostoma sp., Ascaris sp. Fasciola hepatica e Strongyloides stercoralis, cujo fator de redução variou entre 18,2 e 100%. Pode-se observar que houve diferença estatisticamente significante entre o número mais provável de coliformes totais e termotolerantes no esgoto bruto e esgoto tratado, mostrando uma redução na concentração desses organismos indicadores após o tratamento do esgoto na ETE-Ribeirão Preto/SP. Não houve correlação significativa entre as concentrações de coliformes totais e termotolerantes em relação à concentração de cistos de Giardia spp. e oocistos de Cryptosporidium spp.. A análise de vírus mostrou resposta positiva para Rotavirus e Adenovirus em todas as amostras analisadas (esgoto bruto e tratado), mostrando menor absorvância no esgoto tratado. Os resultados obtidos contribuem para a identificação e caracterização de microorganismos de veiculação hídrica no esgoto tratado na ETE-RP, fornecendo dados úteis para a definição de políticas públicas de saneamento, referentes ao controle da qualidade microbiológica do esgoto no país. / Sewage treatment is still precarious in many Brazilian cities, which has contributed to the emergence and re-emergence of waterborne diseases. This study analyzed Giardia spp. cysts and Cryptosporidium spp. oocysts, as well as cysts, eggs and larvae of other protozoa and helminthes. Also part of the study were total and thermotolerant coliforms, Rotavirus and Adenovirus in samples of raw and treated sewage of the Sewage Treatment Station (ETE) of Ribeirão Preto, SP, Brazil. Sewage samples were taken at the points of entry and exit of the ETE, Ribeirão Preto. Analyses of Giardia spp. cysts and Cryptosporidium spp. oocysts were performed through the EPA\'s method 1623. Eggs, cysts and larvae of other protozoa and helminthes were analyzed utilizing the method of sedimentation as proposed by CETESB (1989). Analyses of total and thermotolerant coliforms were performed using the Multiple Tube method (Colilert®). Viral analyses were performed through the RIDASCREEN® enzyme immunoassay ELISA test kit. The results revealed that the concentration of Giardia spp. in raw sewage varied from 120 to 2,200 cysts/L; this concentration varied from 0.45 to 3.5 cysts/L in treated sewage. The concentration of Cryptosporidium spp. oocysts in raw sewage varied from non-detectable to 28.9 oocysts/L and from non-detectable to 1.05 oocysts/L in treated sewage. The activated sludge process used in ETE promoted a partial removal of parasites such as: Endolimax nana, Entamoeba coli, Entamoeba hystolitica, Ancylostoma sp., Ascaris sp. Fasciola hepatica and Strongyloides stercoralis. Reduction factors varied from 18.2 to 100%. A statistically significant difference was observed between the most probable number of total and thermotolerant coliforms in raw and treated sewage, showing a reduction in the concentration of these indicators after the treatment of sewage in ETE, Ribeirão Preto. No statistically significant correlation was found between the concentrations of total and thermotolerant coliforms in relation to the concentration of Giardia cysts spp. and Cryptosporidium spp. oocysts. Analyzing viruses showed positive responses for Rotavirus and Adenovirus in all the studied samples (raw and treated sewage), with a smaller absorbance in the treated sewage. The results contribute to the identification and evaluation of the prevalence of waterborne microorganisms in treated sewage in ETE, Ribeirão Preto, providing useful data for the definition of public policies for sanitation concerning microbiological quality control in Brazil\'s sewage.

O método de diagnóstico coproparasitológico de concentração em formolacetato de etila foi empregado para a quantificação de ovos de helmintos. O método quantitativo proposto foi padronizado utilizando-se o Sistema Comercial Coprotest® e amostras fecais contendo diferentes cargas de ovos de Ascaris lumbricoides. O \"Coprotest quantitativo\" foi aplicado em estudo populacional numa área de baixa endemicidade para parasitas diagnosticáveis através das fezes, e os resultados analisados comparativamente ao método de Kato-Katz. A metodologia proposta foi ainda comparada a outros métodos quantitativos, utilizando-se amostras fecais, preparadas em laboratório, com cargas decrescentes de ovos de A. lumbricoides, Trichuris trichiura e Schistosoma mansoni. Discutem-se as vantagens de se empregar um método capaz de detectar o maior número de espécies, tanto de helmintos quanto de protozoários, . e que permita, concomitantemente, estimar a intensidade das infecções por geohelmintos e S. mansoni nas populações. O \"Coprotest quantitativo\" mostrou ser de aplicação viável em trabalhos de campo, fornecendo resultados comparáveis aos outros métodos quantitativos já descritos na literatura. / Abstracts not available

The aim of this thesis was to search for and identify human and/or animal intestinal parasite eggs in archeological material from medieval period in Brno and Prague. Concentration methods - sedimentation and flotation were used for parasite identification. Polymerase chain reaction (PCR) was used for the detection of parasite DNA. The results were put into context with other data published in similar studies and research.

abstract: The health situation of indigenous peoples is comparable to that of the world's poorest populations, but with the additional burdens of social and cultural marginalization, geographic and cultural barriers to accessing health services, and, in some areas, appropriation of land and natural resources. Cultural transmission (the transfer of beliefs, ideas, and behaviors from one culture to another) from outsider health institutions should presumably aid in closing this health gap by transferring knowledge, practices, and infrastructure to prevent and treat disease. This study examines the biosocial construction of the disease ecology of tuberculosis (TB) in indigenous communities of the Paraguayan Chaco with varying degrees of cultural transmission from outside institutions (government, religious, and NGOs), to determine the influence of cultural transmission on local disease ecologies. Using a biocultural epidemiological framework for the analysis of human infectious disease ecology, this study employed an interdisciplinary, mixed methods approach to examine the interactions of host, pathogen, and the environment in the Paraguayan Chaco. Three case studies examining aspects of TB disease ecology in indigenous communities are presented: (1) The effective cultural transmission of biomedical knowledge to isolated communities, (2) Public health infrastructure, hygiene, and the prevalence of intestinal parasites: co-morbidities that promote the progression to active TB disease, and (3) Community-level risk factors for TB and indigenous TB burden. Findings from the case studies suggest that greater influence from outside institutions was not associated with greater adoption of biomedical knowledge of TB. The prevalence of helminthiasis was unexpectedly low, but infection with giardia was common, even in a community with cleaner water sources. Communities with a health post were more likely to report active adult TB, while communities with more education were less likely to report active pediatric TB, suggesting that healthcare access is the major determinant of TB detection. More research is needed on the role of non-indigenous community residents and other measures of acculturation or integration in TB outcomes, especially at the household level. Indigenous TB burden in the Chaco is disproportionately high, and better understanding of the mechanisms that produce higher incidence and prevalence of the disease is needed. / Dissertation/Thesis / Doctoral Dissertation Social Science and Health 2014

Esgotos urbanos constituem compartimentos ambientais que favorecem a emergência e re-emergência enfermidades de veiculação hídrica. Este estudo objetivou analisar cistos de Giardia spp., oocistos de Cryptosporidium spp., assim como cistos, ovos e larvas de outros protozoários e helmintos patogênicos; Coliformes Totais e Termotolerantes, Rotavírus e Adenovírus em amostras de esgoto bruto e tratado da Estação de Tratamento de Esgoto de Ribeirão Preto - SP. As coletas de esgoto foram realizadas no ponto de entrada e no ponto de saída da ETE-Ribeirão Preto/SP. As análises de cistos de Giardia spp. e oocistos de Cryptosporidium spp. foram realizados pelo Método 1623 da EPA. Ovos, cistos e larvas de outros protozoários e helmintos foram analisados pelo Método de Sedimentação proposto pela CETESB (1989). A análise de coliformes totais e termotolerantes foi realizada pela Técnica de Tubos Múltiplos (Colilert®). A análise de vírus foi realizada através do Teste de Elisa com o KIT da RIDASCREEN® Enzimaimunoensaio. Os resultados obtidos revelaram que a concentração de Giardia spp. no esgoto bruto variou de 120 a 2200 cistos/L, já no esgoto tratado essa concentração variou de 0,45 a 3,5 cistos/L. Com relação aos oocistos de Cryptosporidium spp. a concentração no esgoto bruto variou de não detectável a 28,9 oocistos/L e no esgoto tratado as concentrações variaram de não detectável a 1,05 oocistos/L. O processo de lodos ativados na ETE-RP promoveu uma remoção parcial de parasitas, tais como: Endolimax nana, Entamoeba coli, Entamoeba hystolitica, Ancylostoma sp., Ascaris sp. Fasciola hepatica e Strongyloides stercoralis, cujo fator de redução variou entre 18,2 e 100%. Pode-se observar que houve diferença estatisticamente significante entre o número mais provável de coliformes totais e termotolerantes no esgoto bruto e esgoto tratado, mostrando uma redução na concentração desses organismos indicadores após o tratamento do esgoto na ETE-Ribeirão Preto/SP. Não houve correlação significativa entre as concentrações de coliformes totais e termotolerantes em relação à concentração de cistos de Giardia spp. e oocistos de Cryptosporidium spp.. A análise de vírus mostrou resposta positiva para Rotavirus e Adenovirus em todas as amostras analisadas (esgoto bruto e tratado), mostrando menor absorvância no esgoto tratado. Os resultados obtidos contribuem para a identificação e caracterização de microorganismos de veiculação hídrica no esgoto tratado na ETE-RP, fornecendo dados úteis para a definição de políticas públicas de saneamento, referentes ao controle da qualidade microbiológica do esgoto no país. / Sewage treatment is still precarious in many Brazilian cities, which has contributed to the emergence and re-emergence of waterborne diseases. This study analyzed Giardia spp. cysts and Cryptosporidium spp. oocysts, as well as cysts, eggs and larvae of other protozoa and helminthes. Also part of the study were total and thermotolerant coliforms, Rotavirus and Adenovirus in samples of raw and treated sewage of the Sewage Treatment Station (ETE) of Ribeirão Preto, SP, Brazil. Sewage samples were taken at the points of entry and exit of the ETE, Ribeirão Preto. Analyses of Giardia spp. cysts and Cryptosporidium spp. oocysts were performed through the EPA\'s method 1623. Eggs, cysts and larvae of other protozoa and helminthes were analyzed utilizing the method of sedimentation as proposed by CETESB (1989). Analyses of total and thermotolerant coliforms were performed using the Multiple Tube method (Colilert®). Viral analyses were performed through the RIDASCREEN® enzyme immunoassay ELISA test kit. The results revealed that the concentration of Giardia spp. in raw sewage varied from 120 to 2,200 cysts/L; this concentration varied from 0.45 to 3.5 cysts/L in treated sewage. The concentration of Cryptosporidium spp. oocysts in raw sewage varied from non-detectable to 28.9 oocysts/L and from non-detectable to 1.05 oocysts/L in treated sewage. The activated sludge process used in ETE promoted a partial removal of parasites such as: Endolimax nana, Entamoeba coli, Entamoeba hystolitica, Ancylostoma sp., Ascaris sp. Fasciola hepatica and Strongyloides stercoralis. Reduction factors varied from 18.2 to 100%. A statistically significant difference was observed between the most probable number of total and thermotolerant coliforms in raw and treated sewage, showing a reduction in the concentration of these indicators after the treatment of sewage in ETE, Ribeirão Preto. No statistically significant correlation was found between the concentrations of total and thermotolerant coliforms in relation to the concentration of Giardia cysts spp. and Cryptosporidium spp. oocysts. Analyzing viruses showed positive responses for Rotavirus and Adenovirus in all the studied samples (raw and treated sewage), with a smaller absorbance in the treated sewage. The results contribute to the identification and evaluation of the prevalence of waterborne microorganisms in treated sewage in ETE, Ribeirão Preto, providing useful data for the definition of public policies for sanitation concerning microbiological quality control in Brazil\'s sewage.

O método de diagnóstico coproparasitológico de concentração em formolacetato de etila foi empregado para a quantificação de ovos de helmintos. O método quantitativo proposto foi padronizado utilizando-se o Sistema Comercial Coprotest® e amostras fecais contendo diferentes cargas de ovos de Ascaris lumbricoides. O \"Coprotest quantitativo\" foi aplicado em estudo populacional numa área de baixa endemicidade para parasitas diagnosticáveis através das fezes, e os resultados analisados comparativamente ao método de Kato-Katz. A metodologia proposta foi ainda comparada a outros métodos quantitativos, utilizando-se amostras fecais, preparadas em laboratório, com cargas decrescentes de ovos de A. lumbricoides, Trichuris trichiura e Schistosoma mansoni. Discutem-se as vantagens de se empregar um método capaz de detectar o maior número de espécies, tanto de helmintos quanto de protozoários, . e que permita, concomitantemente, estimar a intensidade das infecções por geohelmintos e S. mansoni nas populações. O \"Coprotest quantitativo\" mostrou ser de aplicação viável em trabalhos de campo, fornecendo resultados comparáveis aos outros métodos quantitativos já descritos na literatura. / Abstracts not available

Submitted by Erika Demachki (erikademachki@gmail.com) on 2015-05-21T19:50:01Z No. of bitstreams: 2 Dissertação - Hanstter Hallison Alves Rezende - 2015.pdf: 1875029 bytes, checksum: a2cbf1f53df5830e4fdd38a866fc6ff4 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2015-05-21T19:53:32Z (GMT) No. of bitstreams: 2 Dissertação - Hanstter Hallison Alves Rezende - 2015.pdf: 1875029 bytes, checksum: a2cbf1f53df5830e4fdd38a866fc6ff4 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-05-21T19:53:32Z (GMT). No. of bitstreams: 2 Dissertação - Hanstter Hallison Alves Rezende - 2015.pdf: 1875029 bytes, checksum: a2cbf1f53df5830e4fdd38a866fc6ff4 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-02-20 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / The domestic cat is an important zoonotic agent for humans, especially as a transmissor of Toxoplasma gondii. The cat is capable of the elimination of millions of oocysts in the environment leading to a massive contamination of these places and leading to a public health issue. Toxoplamosis is a disease with high prevalence throughout the world and the cat is responsible for the parasite’s perpetuation. The evaluation of the accuracy of parasitological diagnostic methods is of vital importance to improve the veterinarian laboratory diagnosis through the use of high sensitivity, specificity and reproducible tests. The aim of this study was to verify the prevalence of intestinal parasites from stray cats in Goiania-GO, to verify the seroprevalence of anti-T. gondii antibodies through the modified aglutination test (MAT) and to perform the evaluation of the accuracy of the parasitological tests applied. Therefore 155 samples of feces and 50 blood samples from stray cats from the Zoonosis Center of Goiania were collected during the year of 2012. The feces samples were processed by the Willis (gold standard), Sheather, Faust and Hoffman-Janer-Pons-Lutz (HJPL) techniques. The MAT was performed in the blood samples. The accuracy was performed through the determination of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and kappa index (k). The intestinal parasites prevalence in the feces from stray cats was 71.68% (115/154). The most prevalent helminth was Ancylostomatids (83.48%, 96/115) and the most prevalent protozoan in monoparasitism was Cystoisospora sp (7.83%, 9/115). T. gondii presented high prevalence (18.27%, 21/115) in fecal samples, 64% in blood samples (32/50) while 36% seronegative (18/50). The accuracy showed that the HJPL and Sheather techniques presented association to the golden standard for the intestinal parasites diagnosis. For the specific diagnosis of T. gondii oocysts the Faust techniques was the one with high accuracy in comparasion to the golden standard, with we emphasize the importance of using two parasitological techniques for the diagnosis of intestinal parasites / O gato doméstico é um importante transmissor de agentes zoonóticos para o homem, em especial Toxoplasma gondii. O gato infectado é capaz de eliminar milhões de oocistos no meio ambiente, provocando uma contaminação maciça nestes locais, sendo considerado um problema de saúde pública. A toxoplasmose é uma doença com alta prevalência em todo o mundo, sendo o gato responsável pela perpetuação do parasito. Avaliar a acurácia de métodos parasitológicos é de extrema importância para melhorar o diagnóstico laboratorial veterinário, utilizando testes de alta sensibilidade, especificidade e reprodutibilidade. O objetivo deste trabalho foi verificar a prevalência de parasitos intestinais em gatos errantes em GoiâniaGO, verificar a soroprevalência de anticorpos anti-T. gondii pelo teste de aglutinação modificado (MAT) e realizar a avaliação da acurácia de técnicas parasitológicas aplicadas no diagnóstico de parasitos intestinais. Foram coletadas 155 amostras de fezes no ano de 2012 no Centro de Controle de Zoonoses de Goiânia-GO e 50 amostras de sangue de gatos no mesmo período. As amostras de fezes foram processadas pelos métodos de Willis (padrão-ouro), Sheather, Faust e Hoffman-Janer-Pons-Lutz (HJPL). Nas amostras de sangue foi realizado o MAT. A análise de acurácia foi realizada determinando a sensibilidade, especificidade, valor preditivo positivo (VPP), valor preditivo negativo (VPN) e índice kappa (k). A prevalência de parasitos intestinais no ano de 2012 foi de 71,68% (115/154), sendo os Ancilostomídeos o helminto mais prevalente 83,48% (96/115), o protozoário mais prevalente foi Cystoisospora sp. em monoparasitismo 7,83% (9/115). T. gondii apresentou alta prevalência: 18,27% (21/115). Ao analisar a soroprevalência de um grupo de 50 animais, 64% (32/50) eram soropositivos e 36% (18/50) soronegativos. A análise de acurácia demonstrou que as técnicas de HJPL e Sheather apresentaram associação ao padrão-ouro para o diagnóstico de parasitos intestinais. No diagnóstico específico de oocistos de T. gondii a técnica de Faust apresentou melhor acurácia comparada ao padrão-ouro, com isso ressaltamos a importância do uso de duas técnicas parasitológicas para o diagnóstico de parasitos intestinais.

Le raton laveur (Procyon lotor) est porteur de nombreux parasites dont certains sont des agents de zoonose. Il nous est apparu opportun d’étudier la faune parasitaire intestinale du raton laveur québécois, particulièrement l’espèce Baylisascaris procyonis. L’étude a donc porté sur l’examen de matières fécales (n = 301) et de contenus intestinaux (n = 203) de 351 ratons laveurs provenant de deux programmes gouvernementaux sur la rage du raton laveur et d’excréments (n = 409) provenant de latrines dans des parcs nationaux du Québec. Des oeufs de B. procyonis étaient excrétés par 23,3 % des ratons laveurs, alors que 29,1 % étaient porteurs de vers. La charge parasitaire moyenne des vers B. procyonis de tout stade variait de 8,5 chez les adultes à 27,1 chez les juvéniles. Chez ces derniers, la charge parasitaire était 11,4 fois supérieure à celle des ratons adultes (p < 0,0001) dont 23,7 fois plus de vers immatures (p < 0,0001) et 9,1 fois plus de vers matures (p = 0,01). Le nombre d’oeufs était 24,7 fois plus élevé chez les ratons juvéniles (p = 0,02) et 50,0 fois moins élevé chez la femelle allaitante. La probabilité du raton d’excréter des oeufs l’automne était de 11,1 (IC95 %: 1,21-101,60) par rapport au printemps et de 21,1 (IC95 %: 2,91-153,18) par rapport à l’été (p < 0,01). La sensibilité (Se) et la spécificité (Sp) de la coproscopie comparée à la nécropsie (norme étalon) ont été calculées en se basant sur l’observation des vers matures (Se : 81,8 %; Sp : 97,7 %) et des vers de tout stade (Se : 53,9 %; Sp : 97,0 %). De plus, la recherche des parasites intestinaux nous a permis de découvrir des ookystes de Giardia (6/159), espèce parasitaire nouvellement rapportée chez le raton. En 2007, nous avons trouvé, par échantillonnage unique, des oeufs de B. procyonis dans 15,8 % des latrines (n = 165) identifiées dans des parcs nationaux du sud du Québec et en 2008, par échantillonnage multiple, dans 89,7 % des latrines (n = 26) actives situées dans des secteurs accessibles à l’homme dans trois parcs nationaux de la Montérégie. Le potentiel zoonotique de B. procyonis est un problème de santé publique qui pourrait devenir sérieux étant donné le pourcentage élevé de ratons laveurs qui excrètent le parasite et qui contaminent des secteurs accessibles par les humains. / Raccoons are carriers of many parasites, some of which are zoonotic. We wanted to expand our knowledge of the Quebec raccoon intestinal parasitic fauna, specifically the Baylisascaris procyonis species. The study consisted of fecal matter (n = 301) and intestinal content examinations (n = 203) collected from 351 raccoons originating from two government programs on raccoon’s rabies and excrements collected (n = 409) from latrines in Quebec national parks. Eggs from B. procyonis were excreted by 23.3 % of raccoons while 29.1 % were worm carriers. The average parasitic burden of all stages of B. procyonis worms varied from 8.5 in adults to 27.1 in juveniles. In juveniles, the parasitic burden was 11.4 times superior to adult raccoons (p < 0.0001) with 23.7 times more immature worms (p < 0.0001) and 9.1 times more mature worms (p = 0.01). The number of eggs was 24.7 times superior in juvenile raccoons (p = 0.02) and 50.0 times lower in breast-feeding females. The probability of raccoons excreting eggs in autumn was 11.1 (IC95 %: 1.21-101.60) in comparison to spring and 21.1 (IC95 %: 2.91-153.18) in comparison to summer (p < 0.01). The sensitivity (Se) and specificity (Sp) of coproscopy compared to necropsy (gold standard) were calculated based on observations of mature worms (Se: 81.8 %; Sp: 97.7 %) and worms of all stages (Se: 53.9 %; Sp: 97.0 %). In addition, our intestinal parasitic research permitted the finding of Giardia oocysts (6/159), which is a newly found parasite species in raccoons. In 2007, B. procyonis eggs were found in 15.8 % of latrines (n = 165) identified in Southern Quebec national parks and in 89.7% of active latrines (n = 26) in three Eastern Townships national parks sites accessible to man in 2008. The zoonotic potential of B. procyonis is a public health issue that could become serious considering the high percentage of raccoons excreting the parasite thus contaminating sectors accessible to man.

The development of molecular tools for detection and typing of unicellular intestinal parasites has revealed genetic diversities in species that were previously considered as distinct entities. Of great importance is the genetic distinction found between the pathogenic Entamoeba histolytica and the non-pathogenic Entamoeba dispar, two morphologically indistinguishable species. Blastocystis sp. is a ubiquitous intestinal parasite with unsettled pathogenicity. Molecular studies of Blastocystis sp. have identified 17 genetic subtypes, named ST1-17. Genetically, these subtypes could be considered as different species, but it is largely unknown what phenotypic or pathogenic differences exist between them. This thesis explores molecular methods for detection and genetic subtyping of unicellular intestinal parasites, with special focus on Blastocystis. We found that PCR-based methods were highly sensitive for detection of unicellular intestinal parasites, but could be partially or completely inhibited by substances present in faeces. A sample transport medium containing guanidinium thiocyanate was shown to limit the occurrence of PCR inhibition. The prevalence of Blastocystis in Swedish university students was over 40%, which is markedly higher than what was previously estimated. Blastocystis ST3 and ST4 were the two most commonly found Blastocystis subtypes in Sweden, which is similar to results from other European countries. Blastocystis sp. and Giardia intestinalis were both commonly detected in Zanzibar, Tanzania, each with a prevalence exceeding 50%. Blastocystis ST1, ST2, and ST3 were common, but ST4 was absent. While G. intestinalis was most common in the ages 2-5 years, the prevalence of Blastocystis increased with increasing age, at least up to young adulthood. We found no statistical association between diarrhoea and Blastocystis sp., specific Blastocystis subtype or G. intestinalis. Metagenomic sequencing of faecal samples from Swedes revealed that Blastocystis was associated with high intestinal bacterial genus richness, possibly signifying gastrointestinal health. Blastocystis was also positively associated with the bacterial genera Sporolactobacillus and Candidatus Carsonella, and negatively associated with the genus Bacteroides. Blastocystis ST4 was shown to have limited intra-subtype genetic diversity and limited geographic spread. ST4 was also found to be the major driver behind the positive association between Blastocystis and bacterial genus richness and the negative association with Bacteroides.

Le raton laveur (Procyon lotor) est porteur de nombreux parasites dont certains sont des agents de zoonose. Il nous est apparu opportun d’étudier la faune parasitaire intestinale du raton laveur québécois, particulièrement l’espèce Baylisascaris procyonis. L’étude a donc porté sur l’examen de matières fécales (n = 301) et de contenus intestinaux (n = 203) de 351 ratons laveurs provenant de deux programmes gouvernementaux sur la rage du raton laveur et d’excréments (n = 409) provenant de latrines dans des parcs nationaux du Québec. Des oeufs de B. procyonis étaient excrétés par 23,3 % des ratons laveurs, alors que 29,1 % étaient porteurs de vers. La charge parasitaire moyenne des vers B. procyonis de tout stade variait de 8,5 chez les adultes à 27,1 chez les juvéniles. Chez ces derniers, la charge parasitaire était 11,4 fois supérieure à celle des ratons adultes (p < 0,0001) dont 23,7 fois plus de vers immatures (p < 0,0001) et 9,1 fois plus de vers matures (p = 0,01). Le nombre d’oeufs était 24,7 fois plus élevé chez les ratons juvéniles (p = 0,02) et 50,0 fois moins élevé chez la femelle allaitante. La probabilité du raton d’excréter des oeufs l’automne était de 11,1 (IC95 %: 1,21-101,60) par rapport au printemps et de 21,1 (IC95 %: 2,91-153,18) par rapport à l’été (p < 0,01). La sensibilité (Se) et la spécificité (Sp) de la coproscopie comparée à la nécropsie (norme étalon) ont été calculées en se basant sur l’observation des vers matures (Se : 81,8 %; Sp : 97,7 %) et des vers de tout stade (Se : 53,9 %; Sp : 97,0 %). De plus, la recherche des parasites intestinaux nous a permis de découvrir des ookystes de Giardia (6/159), espèce parasitaire nouvellement rapportée chez le raton. En 2007, nous avons trouvé, par échantillonnage unique, des oeufs de B. procyonis dans 15,8 % des latrines (n = 165) identifiées dans des parcs nationaux du sud du Québec et en 2008, par échantillonnage multiple, dans 89,7 % des latrines (n = 26) actives situées dans des secteurs accessibles à l’homme dans trois parcs nationaux de la Montérégie. Le potentiel zoonotique de B. procyonis est un problème de santé publique qui pourrait devenir sérieux étant donné le pourcentage élevé de ratons laveurs qui excrètent le parasite et qui contaminent des secteurs accessibles par les humains. / Raccoons are carriers of many parasites, some of which are zoonotic. We wanted to expand our knowledge of the Quebec raccoon intestinal parasitic fauna, specifically the Baylisascaris procyonis species. The study consisted of fecal matter (n = 301) and intestinal content examinations (n = 203) collected from 351 raccoons originating from two government programs on raccoon’s rabies and excrements collected (n = 409) from latrines in Quebec national parks. Eggs from B. procyonis were excreted by 23.3 % of raccoons while 29.1 % were worm carriers. The average parasitic burden of all stages of B. procyonis worms varied from 8.5 in adults to 27.1 in juveniles. In juveniles, the parasitic burden was 11.4 times superior to adult raccoons (p < 0.0001) with 23.7 times more immature worms (p < 0.0001) and 9.1 times more mature worms (p = 0.01). The number of eggs was 24.7 times superior in juvenile raccoons (p = 0.02) and 50.0 times lower in breast-feeding females. The probability of raccoons excreting eggs in autumn was 11.1 (IC95 %: 1.21-101.60) in comparison to spring and 21.1 (IC95 %: 2.91-153.18) in comparison to summer (p < 0.01). The sensitivity (Se) and specificity (Sp) of coproscopy compared to necropsy (gold standard) were calculated based on observations of mature worms (Se: 81.8 %; Sp: 97.7 %) and worms of all stages (Se: 53.9 %; Sp: 97.0 %). In addition, our intestinal parasitic research permitted the finding of Giardia oocysts (6/159), which is a newly found parasite species in raccoons. In 2007, B. procyonis eggs were found in 15.8 % of latrines (n = 165) identified in Southern Quebec national parks and in 89.7% of active latrines (n = 26) in three Eastern Townships national parks sites accessible to man in 2008. The zoonotic potential of B. procyonis is a public health issue that could become serious considering the high percentage of raccoons excreting the parasite thus contaminating sectors accessible to man.