Conselho Nacional de Desenvolvimento Científico e Tecnológico / Neospora caninum and Toxoplasma gondii are two obligate intracellular protozoa and can infect a wide variety of hosts, including birds. Domestic chickens can be considered as sentinels of infection, since they have potential exposure to oocysts in the soil, serving as indicators of environmental contamination, also acting as an efficient source of T. gondii infection. In addition, chickens infected with T. gondii oocysts may contain virulent strains of this parasite in different tissues, without any clinical signs. Therefore, the objectives of this study were (1) to determine the presence of anti-T. gondii and anti-N. caninum in domestic chickens raised extensively in rural areas, (2) evaluate the association of risk factors for infection by T. gondii present in properties in one of the study regions (3) isolating of the parasite T. gondii from tissues of chickens antibody positive (4) genotypically characterize the T. gondii from rural area of the municipality of Santa Maria, Rio Grande do Sul State, Brazil. Firstly, in May 2011 were collected 137 blood samples in some farms in the state and were tested by indirect immunofluorescence (IFA) for antibodies anti-T. gondii and anti-N. caninum and were detected in 74.4% (102/137) and 36.5% (50/137) of chickens, respectively. Later in the period from March 2013 to February 2014 were collected 597 blood samples from 74 properties in the rural area of Santa Maria, RS. The samples were tested by IFA, where 49.2% (294/597) were positive for antibodies anti-T. gondii infection, with titers ranging from 16 to 4096. From bioassay of 12 positive tissues chickens were obtained nine isolates of the parasite. Genotypic characterization of isolates was performed by PCR-RFLP, using 12 genetic markers, SAG1, 5'-3'SAG2, alt. SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, apical. The result of analysis of the genotype of individual of this study revealed the presence of five genotypes according to ToxoDB (# 11, # 55, # 64, # 140 and # 163) plus two new ones, not previously described in literature. The high prevalence of antibodies found in this study suggests a major environmental contamination, and thus a potential risk to human and animal health .From the results in genotypic characterization, it can be observed that there is a wide genetic diversity of T. gondii in the study region, which confirms previous studies in Brazil. / Toxoplasma gondii e Neospora caninum são dois protozoários intracelulares obrigatórios e podem infectar uma grande variedade de hospedeiros, incluindo aves. Galinhas domésticas podem ser consideradas sentinelas da infecção, já que as mesmas têm potencial à exposição aos oocistos presente no solo, servindo como indicadores de contaminação ambiental, atuando também como eficiente fonte de infecção do T. gondii. Além disso, galinhas infectadas com oocistos de T. gondii podem albergar cepas virulentas deste parasito em diferentes tecidos, sem apresentar sinais clínicos. Diante disso, os objetivos deste estudo foram (1) determinar a presença de anticorpos anti-T. gondii e anti-Neospora caninum em galinhas domésticas criadas extensivamente em zona rural, (2) avaliar a associação dos fatores de risco para infecção por T. gondii presentes nas propriedades em uma das regiões de estudo (3) isolar o protozoário T. gondii a partir de tecidos de galinhas anticorpo positivas e (4) caracterizar genotipicamente os isolados de T. gondii de galinhas em área rural do município de Santa Maria, Rio Grande do Sul, Brasil. Primeiramente, em Maio de 2011 foram coletadas 137 amostras de sangue de galinhas em algumas propriedades rurais do estado e foram testadas por Imunofluorescência indireta (RIFI) para anticorpos anti-T. gondii e anti-N. caninum, sendo detectados 74.4% (102/137) e 36.5% (50/137) das galinhas, respetivamente. Posteriormente, no período de março de 2013 a fevereiro 2014 foram coletadas 597 amostras de sangue de galinhas em 74 propriedades da zona rural de Santa Maria, RS.. As amostras foram testadas por RIFI, onde 49,2% (294/597) foram positivas para anticorpos anti-T. gondii, com títulos variando de 16 a 4096. A partir do bioensaio de tecidos de 12 galinhas positivas, obteve-se nove isolados do protozoário. A caracterização genotípica dos isolados foi realizada através da técnica de PCR-RFLP, utilizando os 11 marcadores genéticos, SAG1, 5 -3 SAG2, alt. SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico. O resultado da análise genotípica dos isolados de galinhas do presente estudo revelou a presença de cinco genótipos de acordo com o ToxoDB (#11, #55, #64, #140 e #163), além de dois outros novos, não descritos anteriormente na literatura. A elevada prevalência de anticorpos encontrada neste estudo, sugere uma grande contaminação ambiental, sendo assim um risco potencial para a saúde humana e animal. A partir dos resultados obtidos na caracterização genotípica, pode-se observar que há uma ampla diversidade genética do T. gondii na região de estudo, o que confirma os estudos já realizados no Brasil.

Orientadores: Urara Kawazoe, Elizabeth Santin / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-26T10:12:03Z (GMT). No. of bitstreams: 1 Iuspa_MariaAparecidaMelo_M.pdf: 891258 bytes, checksum: 6e794e24b82f1c94278fc775155f9813 (MD5) Previous issue date: 2014 / Resumo: Foi realizado experimento em frangos de corte machos de duas linhagens, com duração de 42 dias. Foram utilizados 800 frangos de corte machos de um dia de idade alojados em um galpão. O delineamento experimental foi realizado em blocos, num fatorial 2 x 2 (duas linhagens infectadas e não infectadas). Cada tratamento foi replicado oito vezes. Os tratamentos experimentais foram T1, aves da linhagem Cobb 500; T2, aves da linhagem Ross 308, ambos inoculados via oral, aos 14 dias de idade em dose única de 1 x 106 oocistos; T3, aves da linhagem Cobb 500; e T4, aves da linhagem Ross 308, não inoculados. Os critérios de avaliação mensurados foram peso médio das aves, consumo de ração, conversão alimentar ajustada, eficiência alimentar, ganho de peso, escore de lesão, contagem de oocistos e análise de células caliciformes. O escore de lesão das duas linhagens infectadas foi avaliado aos seis dias após a inoculação. O número de oocistos médio por grama de excretas foi obtido entre o quarto e 10º dias após a inoculação. Os resultados de desempenho não mostraram diferenças estatísticas significativas entre as duas linhagens infectadas e as linhagens não infectadas para todos os períodos avaliados, com exceção do peso médio, aos 21 dias de idade. A linhagem Cobb apresentou um peso médio superior ao da linhagem Ross (p<0,001) aos 21 dias de idade. O escore de lesão médio da linhagem Ross foi maior que o da linhagem Cobb (p=0,006). O mesmo foi verificado para o número de oocistos médio por grama de excretas, para o qual a linhagem Ross apresentou maior contagem do que a linhagem Cobb (p<0,0001). Não houve diferença significativa na contagem de células caliciformes de duodeno e jejuno entre os tratamentos. A diferença de desempenho e resistência entre as linhagens infectadas observadas através do peso médio aos 21 dias de idade (sete dias após a inoculação), escore de lesão e quantidade de oocistos por grama de excretas desapareceu conforme o crescimento dos animais até o final do experimento. As reduções relativas de peso médio foram menores na linhagem Cobb, quando comparado à linhagem Ross, e decresceram conforme os animais chegavam à idade final do experimento nas duas linhagens (42 dias). Os aumentos relativos de conversão alimentar foram maiores para a linhagem Cobb quando comparada a linhagem Ross e também decresceram conforme os animais chegavam à idade final do experimento nas duas linhagens (42 dias). A utilização de linhagens de curva de crescimento rápido e curva de crescimento lenta de acordo com o objetivo produtivo (abate precoce ¿ frangos "griller" e abate tardio ¿ frangos pesados) deve ser considerada uma vez que as respostas de desempenho e resistência ao desafio de E. acervulina destas linhagens são distintos, podendo extrair máximo benefício da resistência genética conforme a idade de abate e desafio / Abstract: Evaluation of susceptibility and resistance between two strains of male chicken inoculated with Eimeria acervulina was carried out during 42 days. A total of 800 male broiler chickens with one day of age was used and placed in a floor-pen unit within a typical broiler house. The experimental design was in a randomized block designed in a 2 x 2 factorial (two strains infected and not infected) with eight replications. The treatments were T1, Cobb 500 broiler chicken strain; T2, Ross 308 broiler chicken strain, both were orally inoculated at 14 days of age, with a single dosage of 1 x 106 oocysts; T3, Cobb 500 broiler chicken strain; and T4, Ross 308 broiler chicken, not inoculated. The following criteria were used: average weight, feed consumption, adjustment of feed conversion, feed efficiency, weight gain, lesion score, oocysts counting, caliciform cells analysis. The results of performance did not show statistical differences between infected strains and between non infected strains during all periods, with exception to the average weight of 21 days of age. The Cobb strain showed a higher average weight compared with Ross strain (p<0.001) at 21 days of age. Lesion score evaluated at 6 days after inoculation was higher for Ross strain compared with the Cobb strain (p=0.006). The same result was observed for oocysts counting. The Ross strain presented a higher number of oocysts than the Cobb strain (p<0.0001). There was no statistical difference between strains in caliciform cells of duodenum and jejunum in all treatments. The results showed performance and susceptibility differences between infected strains on the average weight at 21 days of age (seven days after inoculation), lesion score and number of oocysts per gram of excreta; this difference disappeared according the birds were growing up, until the end of trial. The relative average of the weight reduction of the Cobb strain was lower than the Ross, and the relative average weight reduction in both strains decreased according birds were growing up, until the end of trial (42 days of age).The relative feed conversion of the Cobb strain was higher than the Ross strain and the relative feed conversion in both strains decreased according birds were growing up until the end of trial (42 days of age). The use of strains of fast growth and slow growth curve according to the production goal (early-slaughter chickens "griller" and heavy chicken) should be considered once the responses of performance and resistance to E. acervulina challenge of these strains are distinct and it is possible to have the maximum benefit from genetic resistance according to slaughter age and challenge / Mestrado / Relações Antrópicas, Meio Ambiente e Parasitologia / Mestra em Biologia Animal

Os objetivos desse estudo foram avaliar a transmissão transplacentária por N. caninum em diferentes fases da gestação (Exp I) e avaliar diferentes tecidos de bovinos como meio de transmissão de N. caninum em cães jovens e adultos (Exp II). No Exp I, Três cadelas foram inoculadas com 108 taquizoítos de N. caninum na 3ª semana de gestação, três na 6ª semana e uma permaneceu como controle. Todas as cadelas infectadas, e pelo menos um de seus filhotes, apresentaram soroconversão a anticorpos anti-N. caninum pela Reação de Imunofluorescência Indireta. Verificou-se presença do parasita pela coloração de Hematoxilina-Eosina em Sistema Nervoso Central e pela PCR ITS-1 e RFLP em linfonodo, cérebro, coração e fígado. No Exp II, cães jovens e adultos receberam diferentes tecidos de bovinos naturalmente infectados com N. caninum, sendo coração, cérebro, masseter e fígado. Não houve soroconverteu. Apenas os cães jovens eliminaram oocistos de N. caninum ao ingerirem masseter (2 cães, 40%), coração (2 cães, 40%), fígado (1 cão, 33%) e cérebro (3 cães, 75%). / The objectives of this study were to evaluate transplacental transmission of N. caninum in different stages of pregnancy (Exp I) and evaluate different bovine tis.sues as means of transmission of N. caninum in young dogs and adults (Exp II). In Exp I, Three dogs were inoculated with 108 tachyzoites of N. caninum in the third week of gestation, three at 6 sixth week and one remained as a control. All infected dogs, and at least one of their offspring, seroconverted to anti-N. caninum antibodies by Immunofluorescence Assay. There was presence of the parasite by Hematoxylin- Eosine exam in Central Nervous System and by PCR and RFLP ITS-1 in lymph node, brain, heart and liver. In Exp II, young and adult dogs received different tissues of cattle naturally infected with N. caninum: heart, brain, liver and masseter. None seroconverted. Only the young dogs shed oocysts of N. caninum by eating masseter (2 dogs, 40%), heart (2 dogs, 40%), liver (one dog, 33%) and brain (3 dogs, 75%).

The in vitro production of gametocytes and oocysts of the apicomplexan parasite genus Eimeria is still a challenge in coccidiosis research. Until today, an in vitro development of gametocytes or oocysts had only been shown in some Eimeria species. For several mammalian Eimeria species, partial developments could be achieved in different cell types, but a development up to gametocytes or oocysts is still lacking. This study compares several permanent cell lines with primary fetal cells of the black rat (Rattus norvegicus) concerning the qualitative in vitro development of the rat parasite Eimeria nieschulzi. With the help of transgenic parasites, the developmental progress was documented. The selected Eimeria nieschulzi strain constitutively expresses the yellow fluorescent protein and a macrogamont specific upregulated red tandem dimer tomato. In the majority of all investigated host cells the development stopped at the second merozoite stage. In a mixed culture of cells derived from inner fetal organs the development of schizont generations I-IV, macrogamonts, and oocysts were observed in crypt-like organoid structures. Microgamonts and microgametes could not be observed and oocysts did not sporulate under air supply. By immunohistology, we could confirm that wild-type E. nieschulzi stages can be found in the crypts of the small intestine. The results of this study may be helpful for characterization of native host cells and for development of an in vitro cultivation system for Eimeria species.

O trabalho teve por objetivo diagnosticar a infecção experimental e natural por Toxoplasma gondii em pombos (Columba livia), por técnicas sorológicas, biológicas e moleculares. Pombos foram infectados com oocistos esporulados de T. gondii e acompanhados por 60 dias com coleta de soro semanal para o acompanhamento da curva de anticorpos séricos e eutanásia quinzenal para avaliar a presença do parasito em diferentes tecidos. Observou-se concordância em todas as técnicas utilizadas, indicando serem eficazes no diagnóstico da infecção nessa espécie. Pombos de vida livre foram capturados nos municípios de São Paulo, Sorocaba e Ibiúna e anticorpos anti-T. gondii não foram observados. Nestas aves o bioensaio em camundongos foi realizado, independente da ausência de anticorpos e em nenhuma foi possível o isolamento do parasito. / The study aimed to diagnose the experimental and natural infection by Toxoplasma gondii in pigeons (Columba livia), by serological, biological and molecular techniques. Pigeons were infected with sporulated oocysts of T. gondii and monitored for 60 days with weekly serum collection for monitoring the curve of serum antibodies and euthanasia two weeks to assess the presence of parasites in different tissues. Agreement was observed in all the techniques used, indicating to be effective in the diagnosis of infection in this species. Free-living pigeons were captured in the municipalities of São Paulo, Sorocaba and Ibiúna and anti-T. gondii antibodies were not observed. In birds the bioassay was conducted in mice, regardless of the absence of antibodies and none was possible to isolate the parasite.

O trabalho teve por objetivo diagnosticar a infecção experimental e natural por Toxoplasma gondii em pombos (Columba livia), por técnicas sorológicas, biológicas e moleculares. Pombos foram infectados com oocistos esporulados de T. gondii e acompanhados por 60 dias com coleta de soro semanal para o acompanhamento da curva de anticorpos séricos e eutanásia quinzenal para avaliar a presença do parasito em diferentes tecidos. Observou-se concordância em todas as técnicas utilizadas, indicando serem eficazes no diagnóstico da infecção nessa espécie. Pombos de vida livre foram capturados nos municípios de São Paulo, Sorocaba e Ibiúna e anticorpos anti-T. gondii não foram observados. Nestas aves o bioensaio em camundongos foi realizado, independente da ausência de anticorpos e em nenhuma foi possível o isolamento do parasito. / The study aimed to diagnose the experimental and natural infection by Toxoplasma gondii in pigeons (Columba livia), by serological, biological and molecular techniques. Pigeons were infected with sporulated oocysts of T. gondii and monitored for 60 days with weekly serum collection for monitoring the curve of serum antibodies and euthanasia two weeks to assess the presence of parasites in different tissues. Agreement was observed in all the techniques used, indicating to be effective in the diagnosis of infection in this species. Free-living pigeons were captured in the municipalities of São Paulo, Sorocaba and Ibiúna and anti-T. gondii antibodies were not observed. In birds the bioassay was conducted in mice, regardless of the absence of antibodies and none was possible to isolate the parasite.

The in vitro production of gametocytes and oocysts of the apicomplexan parasite genus Eimeria is still a challenge in coccidiosis research. Until today, an in vitro development of gametocytes or oocysts had only been shown in some Eimeria species. For several mammalian Eimeria species, partial developments could be achieved in different cell types, but a development up to gametocytes or oocysts is still lacking. This study compares several permanent cell lines with primary fetal cells of the black rat (Rattus norvegicus) concerning the qualitative in vitro development of the rat parasite Eimeria nieschulzi. With the help of transgenic parasites, the developmental progress was documented. The selected Eimeria nieschulzi strain constitutively expresses the yellow fluorescent protein and a macrogamont specific upregulated red tandem dimer tomato. In the majority of all investigated host cells the development stopped at the second merozoite stage. In a mixed culture of cells derived from inner fetal organs the development of schizont generations I-IV, macrogamonts, and oocysts were observed in crypt-like organoid structures. Microgamonts and microgametes could not be observed and oocysts did not sporulate under air supply. By immunohistology, we could confirm that wild-type E. nieschulzi stages can be found in the crypts of the small intestine. The results of this study may be helpful for characterization of native host cells and for development of an in vitro cultivation system for Eimeria species.

Thesis. (M. Tech. (Dept. of Biosciences, Faculty of Applied and Computer Sciences))--Vaal University of Technology, 2010 / Methods for detecting the presence of Cryptosporidium oocysts and Giardia cysts have been developed and continuous improvement is being done to improve the recovery rate of the target protozoa. Rand Water has adopted their method for isolation and detection of Cryptosporidium oocysts and Giardia cysts in water from United State Environmental Protection Agency (US-EPA) Method 1623, 1999. In 2005 changes were made by US-EPA to the Method 1623. A study was done to improve the performance of the Rand Water Method 06 (2007) used for isolation and detection of Cryptosporidium oocysts and Giardia cysts. Three methods namely: Rand Water Method 06 (2007), US-EPA Method 1623 (2005) and Drinking Water Inspectorate standard operating procedures (2003) were compared and key different steps in the methods were identified (wrist action speed, centrifuge speed, immunomagnetic separation procedures and addition of pre-treatment steps). Different experiments were conducted to verify and evaluate the difference between two wrist action shaker speeds, three different centrifuge speeds, two slightly different immunomagnetic separation procedures and when a pre-treatment step was included in the method. Three different types of water matrices (reagent grade water, drinking water and raw water) were used for the experiments and secondary validation. Data obtained from the experiments and secondary validation was statistically analyzed to determine whether there was a significant difference in the recovery of Cryptosporidium oocysts and Giardia cysts. Secondary validation of the Rand Water Method 06 (2007) was performed by implementing the study experiments‟ findings into the method. The results indicated an increase in the recovery rate of Cryptosporidium oocysts and Giardia cysts when data was compared with the previous secondary validation report. The mean recovery of Cryptosporidium oocysts in reagent grade water samples increased from 31% to 55%, drinking water samples increased from 28% to 44% and raw water decreased from 42% to 29%. The mean recovery of Giardia cysts in reagent grade water samples increased from 31% to 41%, drinking water samples increased from 28% to 46% and raw water decreased from 42% to 32%. Furthermore, even though the recovery rate of raw water decreased the use of pre-treatment buffer reduced the number of IMS performed per sample by reducing the pellet size. Enumeration of microscope slides was also easier as there was less background interference. The optimization of the Rand Water Method 06 (2007) was successful as the recovery rate of Cryptosporidium oocysts and Giardia cysts from water increased. All the changes that were verified and that increased the recovery rate were incorporated into the improved Rand Water Method 06.

[ES] La Agenda 2030 para el Desarrollo Sostenible establece una serie de retos ambiciosos para la comunidad mundial denominados Objetivos de Desarrollo Sostenible (ODS). Entre ellos se encuentran retos específicos como el acceso al agua potable y al saneamiento y una mejor planificación de los recursos hídricos, además de objetivos dirigidos con el fin de combatir las desigualdades y la discriminación, entre los cuales se incluyen los siguientes objetivos generales "no dejar a nadie atrás" y "llegar primero a los más rezagados". Hasta la fecha, se ha demostrado que estos retos son difíciles de cumplir, en parte porque son complejos, pero también debido a la inercia política. Por otra parte, las potabilizadoras son capaces de suministrar agua segura para el consumo humano, sin embargo, es posible que su calidad se vea deteriorada a lo largo de su recorrido por el sistema de distribución antes su llegada al consumidor; si el abastecimiento de agua se ve restringido, las posibilidades de degradación de la calidad física, química y, sobre todo, microbiológica a nivel doméstico se incrementan, por ese motivo, para garantizar la calidad del agua se debe asegurar la integridad física, química y cualitativa del agua. Al aplicar los métodos de análisis de riesgos a los sistemas de agua potable para el consumo humano, se está desarrollando como una importante técnica de gestión preventiva, que ya está ofreciendo resultados muy significativos a la hora de anticiparse a eventuales situaciones de peligro, lo que permite intervenir con rapidez y evitar el impacto de los eventos de origen natural contra las infraestructuras y el agua para el consumo humano. En esta tesis se aborda la problemática de la seguridad del agua destinada al consumidor, identificando los fundamentos de la buena gobernanza y proponiendo un nuevo enfoque para llevar a cabo un análisis del riesgo a lo largo de la cadena del agua, integrando la modelización predictiva y las técnicas de árbol de eventos y de fallos. El estudio ha demostrado la gran capacidad del nuevo enfoque para reproducir escenarios reales y evaluar los niveles de ooquistes después del tratamiento, teniendo en cuenta la heterogeneidad de los aportes resultantes de diferentes niveles de ooquistes contenidos en las aguas superficiales, la eficiencia del tratamiento, los controles del proceso y los aportes de agua. El nuevo planteamiento también puede utilizarse para la evaluación de la exposición de otros agentes patógenos en el agua, y en todas las etapas de la cadena del agua, con el fin de evaluar el impacto real de las desviaciones o los fallos en las condiciones del proceso y los controles de seguridad sobre el riesgo para los consumidores provocado por los agentes patógenos. / [CA] L'Agenda 2030 per al desenvolupament Sostenible estableix una sèrie de reptes ambiciosos per a la comunitat mundial denominat Objectius de Desenvolupament Sostenible (ODS). Aquests inclouen reptes com l'accés a l'aigua, el sanejament segur i una millor gestió de l'aigua, igual que objectius per a afrontar la desigualtat i la discriminació incloent propòsits generals per a "no deixar a ningú arrere" i "arribar primer als més ressagats". Fins hui, s'ha demostrat que aquests reptes són difícils de complir, en part perquè són complexos però també a causa de la inèrcia política. D'altra banda, les plantes de tractament d'aigua potable poden proveir aigua segura per al consum humà, però la seua qualitat es pot alternar durant el pas pel Sistema de Distribució d'Aigua abans d'arribar al consumidor; si el proveïment d'aigua és restringit, la possibilitat de deterioració de la qualitat física, química i principalment microbiològica a nivell intradomiciliària s'incrementa havent-se de protegir la integritat física, hidràulica i de qualitat de l'aigua per a garantir l'assegurament del subministrament de l'aigua potable. L'aplicació dels mètodes d'anàlisi de risc aplicats als serveis d'aigua i sanejament s'està convertint en una estratègia imprescindible en la gestió preventiva, que comença a mostrar resultats importants en l'anticipació oportuna de desastres potencials, facilitant les accions anticipades per a enfrontar les amenaces previsibles per a mitigar els impactes dels esdeveniments naturals en la infraestructura d'aigua i sanejament. En aquesta tesi s'aborda la problemàtica de la seguretat de l'aigua destinada al consumidor, identificant els fonaments de la bona governança i proposant un nou enfocament per a dur a terme una anàlisi de risc al llarg de la cadena de l'aigua, integrant la modelització predictiva i les tècniques d'arbre d'esdeveniments i de fallades. L'estudi ha demostrat la gran capacitat del nou enfocament per a reproduir escenaris reals i avaluar els nivells d'ooquistes després del tractament, tenint en compte l'heterogeneïtat de les aportacions resultants de diferents nivells d'ooquistes continguts en les aigües superficials, l'eficiència del tractament, els controls del procés. L'eficiència de la planta, l'eficiència del tractament, els controls del procés i les aportacions d'aigua. El nou plantejament també pot utilitzar-se per a l'avaluació de l'exposició d'altres agents patògens en l'aigua i en totes les etapes de la cadena de l'aigua, amb la finalitat d'avaluar l'impacte real de les desviacions o les fallades en les condicions del procés i els controls de seguretat sobre el risc per als consumidors provocat per agents patògens. / [EN] The 2030 Agenda for Sustainable Development sets out a series of ambitious challenges for the global community. These Sustainable Development Goals (SDGs) include targets for access to safe water and sanitation and improved water management, as well as goals to tackle inequality and discrimination, including overarching proposals to "leave no one behind" and "reach the most disadvantaged first". To date, these are challenges that have proved difficult to meet, partly because they are complex, but also because of political inertia. On the other hand, drinking water treatment plants can provide safe water for human consumption, but its quality can be altered during its passage through the water distribution system before it reaches the consumer; if the water sup-ply is restricted, the possibility of physical, chemical and mainly microbiological quality detection at the household level increases, and the physical, hydraulic and quality integrity of the water must be protected to ensure the safety of the drinking water supply. The application of risk analysis methods applied to water and sanitation ser-vices is becoming an important preventive management strategy, which is be-ginning to show significant results in the timely anticipation of potential disas-ters, facilitating anticipatory actions to address foreseeable hazards and to mit-igate the impacts of natural events on water and sanitation infrastructure. This thesis addresses the issue of consumer water safety by identifying the fundamentals of good governance and proposing a new approach for conduct-ing risk analysis along the water chain, integrating predictive modelling and event and fault tree techniques. The study has demonstrated the high capacity of the new approach to reproduce real scenarios and to evaluate the levels of oocysts after treatment, taking into account the heterogeneity of the inputs resulting from different levels of oocysts contained in the surface water, the efficiency of the treatment, the process controls and the water in-puts. The new approach can also be used for exposure assessment of other pathogens in water, and at all stages of the water chain, to assess the real im-pact of deviations or failures in process conditions and safety controls on the risk to consumers from pathogens. / Kombo Mpindou, GOM. (2023). Aportación a la implantación del análisis de riesgo en los sistemas de distribución del agua: caso del Cryptosporidium para distintos niveles de desarrollo tecnológico en la potabilizadora [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/193340