No description available.

Background: Access to improved water and sanitation are key measures of the World Health Organizations. However, while a community can be classified as having access to improved water and sanitation, the possibility of microbiological contaminations exists. Globally, there is a need to assess the quality of drinking water to better classify levels of microbiological quality in attempts to reduce diarrheal disease burden. Utilizing the test for hydrogen sulfide (H2S) producing bacteria test is a cost effective and easy to use method that may be comparable to the traditional yet more costly method (IDEXX Colilert Quantitray). Due to a paucity of data on the test for H2S producing bacteria, this study was performed to examine how well the test for hydrogen sulfide (H2S) producing bacteria compared to traditional measure of fecal indicator bacteria total coliforms and E. coli in drinking water. Furthermore, an analysis of the ability of the test for H2S producing bacteria to predict diarrheal disease was also examined. Methods: The following conditions for the H2S were examined in the study: 2 volumes (10mL or 90mL), 2 incubation times (24 and 48 hours) and the use of a semi-quantitative scoring system that measured the intensity of the black precipitate formed (H2S). To examine how well these conditions compared to E. coli and total coliform results, the following analyses were performed: 1) analysis of sensitivity and specificity to examine presence/absence of bacteria in both samples, 2) linear regression to examine how well a semi-quantitative H2S scoring system predicted bacterial concentrations and 3) logistic regression to examine how well the H2S test predicted risk of diarrheal disease. Results: Within the dataset, there were 816 observations among the 7 communities involved in the study. The H2S test condition that had the highest sensitivity and specificity (94.23% and 36.07% respectively) for total coliforms was 90mL volume at 48 hours. This test condition also produced the highest sensitivity and specificity for E. coli (97.82% and 78.67%, respectively). An analysis using linear regression demonstrated that a semi-quantitative H2S scoring system was able to predict both total coliform and E. coli concentrations in the same samples. In a logistic regression analysis of diarrheal disease, the test of H2S producing bacteria suggested an increase in diarrheal disease risk for higher levels of H2S (OR of 1.18 (p=0.03; 1.02 – 1.35)). Discussion: The initial results here suggest that the use of the test for H2S producing bacteria has potential with high sensitivity (>90%) for E. coli and total coliforms. The application of the semi-quantitative scoring system may also have applications in predicting concentration of E. coli and total coliforms and well as possibly predicting diarrheal disease. However, more work needs to be completed to standardize the semi-quantitative approach to reduce subjectivity of scoring as well as examine the role of the test in additional epidemiologic studies. INDEX WORDS: waterborne disease, E. coli, Dominican Republic, microbial testing

Climate change is expected to cause changes in precipitation and runoff patterns, likely increasing the risk of waterborne infectious disease in some areas. In this context, the research objectives were to describe links between weather, water quality, and infectious gastrointestinal illnesses (IGI) in Nunatsiavut, Canada, which necessarily involved evaluating the quality and usefulness of data captured by the local health registry system. For this evaluation, IGI was used as a reference syndrome. Community-based meteorological stations captured weather data; trained local personnel conducted water quality testing. Clinic records provided IGI-related data (2005-2008). This study is the first to systematically gather and describe baseline empirical data on weather, water quality, and health in Nunatsiavut. It showed the necessity of improving Inuit health data quality and monitoring environmental health variables consistently and systematically across all Arctic regions. These data are critical to inform adaptation strategies for managing impacts of climate change on health.

The risk of waterborne infections acquired from the consumption of contaminated water is related to changes in source water fecal contamination, which is often influenced by land-use and hydro-meteorological conditions in the surrounding watershed. The impact of land-use composition on surface water contamination was explored in order to determine the risk of surface water contamination associated with land-use change. Highest contamination was observed in watersheds characterized by more than 12.5% agricultural and more than 1.6% urban land (mean fecal coliform (FC) concentration of these 5 sites = 135 CFU 100ml-1 while the British Columbia (BC) raw water quality guideline = 100 CFU 100ml-1). Contamination increased exponentially, and violated BC raw water quality guidelines with greater frequency, in relation to greater agricultural land in the upstream watershed. Additional factors, such as sewage treatment plants, low dilution in smaller streams, and higher temperatures were also associated with greater contamination. These results indicate the high level of risk posed by agricultural and urban development and the need for source water protection. Fecal contamination levels in source water are also influenced by rainfall and snowmelt-induced surface runoff that transport diffuse fecal contaminants into surface water. Seasonal levels of fecal contamination in surface water was related to the watershed hydro-climatic regime for around half of the watersheds examined. Watersheds with snowmelt-dominant (SD) runoff regimes showed stronger evidence of hydro-meteorological variability driving seasonal contamination levels than those with rainfall and snowmelt-influenced (RSI) and rainfall-dominant (RD) runoff regimes, and thus are more prone to experiencing changes to seasonal variability resulting from climate change. Projected increases in mean annual temperatures of between 1.70C and 4.00C towards the end of the 21st century will alter existing runoff regimes within watersheds. For SD watersheds that remain below freezing and continue to accumulate snowpack during the cold season, transport of fecal contamination will likely occur earlier in the year with greater intensity. Fecal coliform transport in summer is likely to decrease, especially in SD watersheds in which fecal contamination is driven by summer rainfall events. Snowmelt-dominant watersheds transitioning toward a RD runoff regime will experience less contamination during spring but increased contamination during late fall and winter. The extent to which these changes in runoff regime will influence surface water fecal contamination will vary among watersheds. Further investigation is required to identify factors that enhance or mitigate the association of surface water fecal contamination with rainfall and snowmelt-induced runoff in order to identify specific site vulnerability to changing seasonal contamination levels. Total precipitation within BC is projected to increase by 20-30% towards the end of the 21st century. The association of annual FC variability with snowmelt and rainfall variability was examined in order to assess the capacity of such increases to raise the level of surface water fecal contamination. Greater total annual and seasonal rainfall and/or river discharge increased surface water fecal contamination for 58% (11/19) of the sites examined. Hydro-meteorological variability influenced FC concentration during winter, the season of greatest precipitation, and spring, the season of greatest snowmelt, but not during summer or fall. Reduced contamination levels during the El Niño event in 2002/03 were associated with a mean reduction in river discharge during spring and summer. These associations suggest that the risk of increased surface water fecal contamination in response to higher precipitation is likely to be greatest in winter for RD watersheds and spring for SD watersheds, although the magnitude of impact will vary among sites. Climate change and land-use activities within watersheds have the capacity to alter the timing and amount of surface water fecal contamination. These factors are likely to act synergistically by increasing the presence and transport of fecal contaminants within watersheds. Such relationships should be carefully considered to aid the assessment and mitigation of the risk of source water contamination associated with land-use and climate change. / Graduate

To protect public health, drinking water systems are monitored for indicator organisms that correlate with fecal contamination and suggest the presence of human pathogens. Total coliforms, fecal coliforms, and E. coli are the most commonly used indicator organisms. These bacteria generally colocate with fecal pollution, but some limitations exist. In particular, the ability of indicator bacteria to predict the presence of enteric viruses is questionable because of distinct transport and survival characteristics of bacteria and viruses. Although viral indicators of enteric viruses have been proposed, none have been implemented into the current regulatory framework. In this thesis, the correlation of bacteria and viruses in drinking water sources and treatment systems is reviewed, and the potential of Torque Teno virus (TTV) to qualify as an indicator virus is discussed. TTV is unique among enteric viruses as it infects approximately 80% of healthy individuals worldwide, is transmitted by the fecal-oral route, causes no observable illness, and lacks seasonal fluctuations.

Pathogen contamination, typically quantified by elevated levels of fecal indicator bacteria (FIB), remains the leading cause of surface water-quality impairments in the United States. Continuous watershed-scale models are typically employed to facilitate Total Maximum Daily Load (TMDL) restoration efforts. Due to limited understanding of microbial fate and transport, predictions of FIB concentrations are associated with considerable uncertainty relative to other water-quality contaminants. By focusing on a data-rich instrumented urban watershed, this study aims to improve understanding of microbial fate and transport processes. Weekly FIB concentrations in both the water column and streambed sediments were monitored for one year, and statistical correlations with hydrometeorological and physicochemical variables were identified. An intensive six storm intra-sampling campaign quantified and contrasted loading trends of both traditional regulatory FIB and emerging Microbial Source Tracking (MST) markers. Together, these intensive monitoring efforts facilitated evaluation of the impacts of bacteria-sediment interactions on the predictions of daily FIB concentrations in Hydrological Simulation Program-Fortran (HSPF) over multiple years. While superior overall model performance was demonstrated as compared to earlier efforts, the inclusion of bacteria-sediment interactions did not improve performance. Large wet-weather microbial loading appears to have dwarfed the effects of FIB release and resuspension from sediment. Although wet-weather loading is generally considered as a primary source of waterbody microbial loads, dry-weather periods are more directly associated with public health concern, which may be a more suitable area for future model-refinement efforts. Site evaluation is critical to determine whether the added model complexity and effort associated with partitioning phases of FIB can be sufficiently offset by gains in predictive capacity. Finally, a stochastic framework to translate simulated daily FIB concentrations into estimates of human illness risks is presented that can be can be readily integrated into existing TMDLs. As even small concentrations of FIB from human sources are associated with great risk, and monitoring efforts indicated moderate/high levels of human-associated MST marker in this watershed, remediation efforts to protect public health would be best directed toward infrastructure improvements. Uncertainty analysis indicates more site-specific knowledge of pathogen presence and densities would best improve the estimation of illness risks. / Ph. D.

No description available.

A toxoplasmose é uma zoonose de distribuição mundial, altamente prevalente na população humana e animal. A doença é geralmente benigna e autolimitada, mas pode ocasionar déficits visuais graves em cerca de 2 a 3% dos indivíduos acometidos, e ainda, assumir formas graves e letais em pacientes imunossuprimidos e em fetos de gestantes com infecção aguda. As principais formas de transmissão da doença são o consumo de água e alimentos crus contaminados com oocistos e a ingestão de carne crua ou mal cozida contendo cistos teciduais do Toxoplasma gondii. Na literatura há relatos de vários surtos epidêmicos de toxoplasmose humana, porém a análise descritiva destes surtos é pontual e restrita, com informações isoladas em relação período de incubação e gravidade dos sintomas que poderiam estar relacionados à forma infectante do agente. No presente trabalho analisamos a influência da forma infectante do T. gondii no quadro da doença aguda humana, através de revisão sistemática das principais bases de dados bibliográficos na área de Saúde Pública (Cochrane, Embase, Food Sciences & Tech Abstracts, Lilacs, PubMed, Scopus e Web of Science), além de publicações em boletins epidemiológicos (Boletim Epidemiológico Paulista, Boletim Eletrônico Epidemiológico SVS) e anais de congressos nacionais e internacionais de áreas correlatas. As pesquisas nas bases de dados bibliográficos foram realizadas utilizando idiomas em português e inglês para os termos: surtos de toxoplasmose humana (human toxoplasmosis outbreak). Os critérios de inclusão dos estudos levaram em consideração artigos e resumos que relatassem surtos epidêmicos de toxoplasmose humana com descrição da forma infectante do agente e quadro clínico da doença. Na busca eletrônica inicial, foram obtidos 431 artigos referentes a surtos mundiais e nacionais de toxoplasmose humana, provenientes de diferentes formas de transmissão da doença, porém foram elegíveis para o trabalho somente 33 artigos, incluindo um surto ocorrido recentemente na região de Araraquara, Estado de São Paulo, cuja investigação epidemiológica foi conduzida por nossa equipe. A análise da revisão sistemática sugere que o número de casos confirmados nos surtos é maior quando a transmissão ocorre por oocistos, sendo o solo e a água associados a esta forma de transmissão. Quanto aos achados clínicos, a infecção por cistos parece induzir um período de incubação menor do que o observado para oocistos. Não houve relação da forma infectante com o sexo predominante e faixa etária nas populações amostrais. Os surtos foram descritos mais frequentemente nas Américas que em outros continentes. Estes dados sugerem que a forma infectante do T.gondii interfere no quadro da toxoplasmose aguda. / Toxoplasmosis is a zoonosis of worldwide distribution, highly prevalent in the human and animal population. The disease is usually benign and self-limiting but can cause severe visual deficits in about 2 to 3% of affected individuals, and also take serious and lethal in immunosuppressed patients and in fetuses of pregnant women with acute infection. The most important modes of transmission are consumption of water and uncooked food contaminated with oocysts and the ingestion of raw or undercooked meat containing tissue cysts of Toxoplasma gondii. In literature there are reports of several human toxoplasmosis outbreaks, but the descriptive analysis of these outbreaks is punctual and restricted, with isolated information regarding the incubation period and severity of symptoms that could be related to the infective form of the agent. In this study we analyze the influence of infective form of T. gondii in the context of acute human disease, through a systematic review of the major bibliographic databases in the area of Public Health (Cochrane, Embase, Food Sciences & Tech Abstracts, Lilacs, PubMed, Scopus e Web of Science), as well as publications in epidemiological bulletins (Boletim Epidemiológico Paulista, Boletim Eletrônico Epidemiológico SVS) and annals of national and international conferences in related areas. This research on bibliographic databases was performed using English and Portuguese languages for the terms: human toxoplasmosis outbreak (surtos de toxoplasmose humana). The inclusion criteria of the studies took into consideration articles and abstracts that reported outbreaks of human toxoplasmosis with description of the infective form of the agent and the clinical disease. In the initial electronic search, 431 articles were obtained regarding global and national outbreaks of human toxoplasmosis from different main forms of disease transmission, but were eligible to work only 33 articles, including a recent outbreak in the region of Araraquara State of São Paulo, which epidemiological investigation was conducted by our team. The analysis of systematic review suggests that the number of confirmed cases in outbreaks is greater when the transmission occurs by oocysts, and the soil and water are associated with this form of transmission. Regarding clinical findings, cysts infection seems to induce an incubation period less than that observed for oocysts. No relationship between the infective form with the predominant sex and age group in the sample populations. Outbreaks were reported more frequently in the Americas than in other continents. These data suggest that the infective form of T. gondii interferes in the context of acute toxoplasmosis.

Waterborne diseases continue to plague the poorest people in low-income countries and are estimated to cause 4,600,000 acute incidents of diarrhea resulting in over 2,000 deaths daily. A major challenge is performing microbiology tests to monitor drinking water quality. Friends of the Old (FOTO) implemented a novel strategy using evidence-based microbiology to educate communities about the relationship between contaminated water and disease. Two commercially available tests for E.coli, adapted for fieldwork, provided easily interpreted results of contamination that correlate with WHO's disease risk categories. Simple and effective household water treatment options 'solar pasteurization and/or chlorination' were provided to all 14,400 families and 42 schools in Lower Nyakach, Kenya. From February to May, 2015, adjacent districts had serious cholera outbreaks, but in Lower Nyakach, where education and the use of chlorine were nearly universal, there were no cases of cholera and steadily decreasing rates of diarrhea. A cross-sectional study was conducted to verify self-reported water treatment practices with evidence-based microbiological testing. A random sample of 377 households revealed that 95% treat their water each and every time they collect. Microbiological verification found 96% of household safe water storage vessels were low risk compared to their very high risk source water. A strong association (p < 0.001) existed between the observed decrease in diarrhea trends from health facilities in Lower Nyakach and exposure to the novel training. The strategy used by FOTO could be replicated to empower communities worldwide to identify contaminated drinking water sources and to reduce the incidence of waterborne disease.

A toxoplasmose é uma zoonose de distribuição mundial, altamente prevalente na população humana e animal. A doença é geralmente benigna e autolimitada, mas pode ocasionar déficits visuais graves em cerca de 2 a 3% dos indivíduos acometidos, e ainda, assumir formas graves e letais em pacientes imunossuprimidos e em fetos de gestantes com infecção aguda. As principais formas de transmissão da doença são o consumo de água e alimentos crus contaminados com oocistos e a ingestão de carne crua ou mal cozida contendo cistos teciduais do Toxoplasma gondii. Na literatura há relatos de vários surtos epidêmicos de toxoplasmose humana, porém a análise descritiva destes surtos é pontual e restrita, com informações isoladas em relação período de incubação e gravidade dos sintomas que poderiam estar relacionados à forma infectante do agente. No presente trabalho analisamos a influência da forma infectante do T. gondii no quadro da doença aguda humana, através de revisão sistemática das principais bases de dados bibliográficos na área de Saúde Pública (Cochrane, Embase, Food Sciences & Tech Abstracts, Lilacs, PubMed, Scopus e Web of Science), além de publicações em boletins epidemiológicos (Boletim Epidemiológico Paulista, Boletim Eletrônico Epidemiológico SVS) e anais de congressos nacionais e internacionais de áreas correlatas. As pesquisas nas bases de dados bibliográficos foram realizadas utilizando idiomas em português e inglês para os termos: surtos de toxoplasmose humana (human toxoplasmosis outbreak). Os critérios de inclusão dos estudos levaram em consideração artigos e resumos que relatassem surtos epidêmicos de toxoplasmose humana com descrição da forma infectante do agente e quadro clínico da doença. Na busca eletrônica inicial, foram obtidos 431 artigos referentes a surtos mundiais e nacionais de toxoplasmose humana, provenientes de diferentes formas de transmissão da doença, porém foram elegíveis para o trabalho somente 33 artigos, incluindo um surto ocorrido recentemente na região de Araraquara, Estado de São Paulo, cuja investigação epidemiológica foi conduzida por nossa equipe. A análise da revisão sistemática sugere que o número de casos confirmados nos surtos é maior quando a transmissão ocorre por oocistos, sendo o solo e a água associados a esta forma de transmissão. Quanto aos achados clínicos, a infecção por cistos parece induzir um período de incubação menor do que o observado para oocistos. Não houve relação da forma infectante com o sexo predominante e faixa etária nas populações amostrais. Os surtos foram descritos mais frequentemente nas Américas que em outros continentes. Estes dados sugerem que a forma infectante do T.gondii interfere no quadro da toxoplasmose aguda. / Toxoplasmosis is a zoonosis of worldwide distribution, highly prevalent in the human and animal population. The disease is usually benign and self-limiting but can cause severe visual deficits in about 2 to 3% of affected individuals, and also take serious and lethal in immunosuppressed patients and in fetuses of pregnant women with acute infection. The most important modes of transmission are consumption of water and uncooked food contaminated with oocysts and the ingestion of raw or undercooked meat containing tissue cysts of Toxoplasma gondii. In literature there are reports of several human toxoplasmosis outbreaks, but the descriptive analysis of these outbreaks is punctual and restricted, with isolated information regarding the incubation period and severity of symptoms that could be related to the infective form of the agent. In this study we analyze the influence of infective form of T. gondii in the context of acute human disease, through a systematic review of the major bibliographic databases in the area of Public Health (Cochrane, Embase, Food Sciences & Tech Abstracts, Lilacs, PubMed, Scopus e Web of Science), as well as publications in epidemiological bulletins (Boletim Epidemiológico Paulista, Boletim Eletrônico Epidemiológico SVS) and annals of national and international conferences in related areas. This research on bibliographic databases was performed using English and Portuguese languages for the terms: human toxoplasmosis outbreak (surtos de toxoplasmose humana). The inclusion criteria of the studies took into consideration articles and abstracts that reported outbreaks of human toxoplasmosis with description of the infective form of the agent and the clinical disease. In the initial electronic search, 431 articles were obtained regarding global and national outbreaks of human toxoplasmosis from different main forms of disease transmission, but were eligible to work only 33 articles, including a recent outbreak in the region of Araraquara State of São Paulo, which epidemiological investigation was conducted by our team. The analysis of systematic review suggests that the number of confirmed cases in outbreaks is greater when the transmission occurs by oocysts, and the soil and water are associated with this form of transmission. Regarding clinical findings, cysts infection seems to induce an incubation period less than that observed for oocysts. No relationship between the infective form with the predominant sex and age group in the sample populations. Outbreaks were reported more frequently in the Americas than in other continents. These data suggest that the infective form of T. gondii interferes in the context of acute toxoplasmosis.