Intervention studies and the definition of dominant transmission routes
TL;DR: The implications for the analysis of real-world data are analyzed by examining data on the importance of water and other transmission routes for cholera in Bangladesh by using a quantitative model to generate synthetic data.
Abstract: A common approach to assessing the relative importance of different transmission routes is to eliminate transmission through one route and assume that the ratio "number of cases eliminated:number of residual cases" measures the relative importance of the eliminated route vis-a-vis the residual transmission route. A quantitative model is used to generate synthetic data similar to those analyzed by epidemiologists. These data are analyzed using this conventional procedure and the inferences drawn from the synthetic data compared with the causal relationships structured into the model. The implications for the analysis of real-world data are analyzed by examining data on the importance of water and other transmission routes for cholera in Bangladesh.
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01 Jan 2001
TL;DR: This document is an output from a project funded by the UK Department for International Development for the benefit of low-income countries and the views expressed are not necessarily those of DFID.
Abstract: isab watsan litreview2 isab watsan litreview2 Water supply and sanitation access and use by physically disabled people Any part of this publication may be copied, reproduced or adapted to meet local needs, without permission from the authors, provided the parts reproduced are distributed free, or at cost and not for commercial ends, and the source is fully acknowledged as given below. Please send copies of any materials in which text or illustrations have been used to WEDC Publications at the address given overleaf. (2002) Water supply and sanitation access and use by physically disabled people: literature review. WEDC, Loughborough University, UK. This document is an output from a project funded by the UK Department for International Development (DFID) for the benefit of low-income countries. The views expressed are not necessarily those of DFID. Designed and produced at WEDC. iii Acknowledgements The authors would like to thank the following for their valuable contributions to this publication: Barbara Dobson from the Centre for Research in Social Policy, Loughborough University, for guidance and comments on Chapter 3. Advisory Panel members for comments: Heather Payne, Healthlink Worldwide UK, for remedying omissions, constructive comments and proofreading of the final draft. Adam Platt, Helpage International, for additional references and up-to-date research findings. for supplying video images on which the cover illustration was based. iv Contents List of acronyms vii 1. Introduction 1 1.1 Scope of the review 1 1.2 Background context 1 1.2.1 Human rights 2 1.2.2 The social model of disability 3 1.2.3 Poverty and disability 3 1.2.4 Economics 4 1.2.5 Mainstreaming 5 1.2.6 Disability in different cultures 6 1.3 Problem statement 6 1.4 Purpose of research, review, methodology, limitations 7 1.5 Definitions of some concepts and terms used in this study 7 1.5.1 Physical disabilities: 7 1.5.2 Domestic water cycle 8 1.5.3 Access/accessibility 8 1.5.4 Low-income communities 8 1.6 Report structure and format 8
33 citations
04 Dec 2009
TL;DR: This year's annual review of development effectiveness (ARDE) is being written against the backdrop of a global financial crisis, declining growth, and massive fiscal stimulus efforts to revitalize markets as mentioned in this paper.
Abstract: This year's annual review of development effectiveness (ARDE) is being written against the backdrop of a global financial crisis, declining growth, and massive fiscal stimulus efforts to revitalize markets. Demand for greater development support from the World Bank has grown, along with concerns that resources be used effectively and efficiently to achieve their development objectives. This ARDE focuses on the Bank's performance record in getting results from its projects and country programs and, as is customary, examines in depth one topic relating to development effectiveness. The focus of this ARDE is on the Bank's support for environmental sustainability, in response to a Board request for a synthesis of findings from recent Independent Evaluation Group (IEG) reports on the environment. This year's special focus getting results for sustainable development reflects the vital role of sound environmental stewardship for development and the grave threat that inaction poses of reversing gains in growth and poverty reduction. The Bank's record in implementing the 2001 environment strategy and advancing the results agenda is quite mixed. New sources of financing, including resources for global efforts, have helped lending and support for the environment to recover from the lows of the early 2000s; analytic work has fostered innovative approaches and enhanced environmental awareness; and direct support for environmental projects is showing improved performance, with tangible results. But implementation of the strategy in mainstream environmental work across sectors has been weak and must be strengthened. Project performance shows a clear improving trend.
32 citations
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TL;DR: This paper conducted a controlled before-and-after trial to evaluate the impact of an onsite urban sanitation intervention on the prevalence of enteric infection, soil transmitted helminth re-infection, and diarrhea among children in Maputo, Mozambique.
Abstract: We conducted a controlled before-and-after trial to evaluate the impact of an onsite urban sanitation intervention on the prevalence of enteric infection, soil transmitted helminth re-infection, and diarrhea among children in Maputo, Mozambique A non-governmental organization replaced existing poor-quality latrines with pour-flush toilets with septic tanks serving household clusters We enrolled children aged 1-48 months at baseline and measured outcomes before and 12 and 24 months after the intervention, with concurrent measurement among children in a comparable control arm Despite nearly exclusive use, we found no evidence that intervention affected the prevalence of any measured outcome after 12 or 24 months of exposure Among children born into study sites after intervention, we observed a reduced prevalence of Trichuris and Shigella infection relative to the same age group at baseline (<2 years old) Protection from birth may be important to reduce exposure to and infection with enteric pathogens in this setting
31 citations
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TL;DR: The study shows that 84% of respondents were aware of various sources of rainwater contamination, but only 5% were aware that they needed to adjust use ofRainwater, depending on whether they cleaned the tank or not and most of the respondents were not aware that gutter cleaning was necessary to improve water quality.
Abstract: Given the possibility of waterborne diseases caused by inappropriate rainwater harvesting systems, a survey was conducted in Uganda to assess existing knowledge of both physical and non-physical measures that safeguard harvested rainwater. Households who had received rainwater tanks were assessed on issues related to harvested rainwater quality. The study shows that 84% of respondents were aware of various sources of rainwater contamination, but only 5% were aware that they needed to adjust use of rainwater, depending on whether they cleaned the tank or not. Most of the respondents were not aware that gutter cleaning was necessary to improve water quality. Indeed, as the water from the collection surface is channelled through gutters, a number of measures need to be taken to control the entry of contaminations and subsequent growth of pathogens in the tank, e.g. first flush diverts, installation of filters, chemical use and mesh cleaning. The majority, however, did not take adequate care of the gutters and this impacts on health and social livelihood. Overall, the findings emphasize the need to provide more information to households when installing water harvesting tanks to ensure that the harvested rainwater is of high quality.
29 citations
Cites background from "Intervention studies and the defini..."
...water for person and domestic hygiene in addition to drinking-water quality (Briscoe 1984; Clasen & Cairncross 2004; Wright et al. 2004)....
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TL;DR: The results support the choice of HAV as a sentinel disease that is associated with level of sanitation and introduce monotonic splines as a novel non-parametric approach to estimate incidence from prevalence data.
Abstract: Background To assess the impact of water sanitation and sewage disposal, part of a major environmental control programme in Rio de Janeiro, we carried out seroprevalence studies for Hepatitis A virus (HAV) in three micro-regions in Rio de Janeiro. Each region varied with regard to level of sanitation. We are interested in assessing the discriminating power of age-specific prevalence curves for HAV as a proxy for improvement in sanitation. These curves will serve as baseline information to future planned surveys as the sanitation programme progresses. Methods Incidence rate curves from prevalence data are estimated parametrically via a Weibull-like survival function, and non-parametrically via maximum likelihood and monotonic splines. Sera collected from children and adults in the three areas are used to detect antibodies against HAV through ELISA. Results We compare baseline incidence curves at the three sites estimated by the three methods. We observe a strong negative correlation between level of sanitation and incidence rates for HAV infection. Incidence estimates yielded by the parametric and non-parametric approaches tend to agree at early ages in the microregion showing the best level of sanitation and to increasingly disagree in the other two. Conclusion Our results support the choice of HAV as a sentinel disease that is associated with level of sanitation. We also introduce monotonic splines as a novel non-parametric approach to estimate incidence from prevalence data. This approach outperforms current estimating procedures.
29 citations
References
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06 Mar 2012
TL;DR: It would occupy a long time to give an account of the progress of cholera over different parts of the world, with the devastation it has caused in some places, whilst it has passed lightly over others, or left them untouched; and unless this account could be accompanied with a description of the physical condition of the places, and the habits of the people, which I am unable to give, it would be of little use.
Abstract: It would occupy a long time to give an account of the progress of cholera over different parts of the world, with the devastation it has caused in some places, whilst it has passed lightly over others, or left them untouched; and unless this account could be accompanied with a description of the physical condition of the places, and the habits of the people, which I am unable to give, it would be of little use. There are certain circumstances, however, connected with the progress of cholera, which may be stated in a general way. It travels along the great tracks of human intercourse, never going faster than people travel, and generally much more slowly. In extending to a fresh island or continent, it always appears first at a sea-port. It never attacks the crews of ships going from a country free from cholera to one where the disease is prevailing, till they have entered a port, or had intercourse with the shore. Its exact progress from town to town cannot always be traced; but it has never appeared except where there has been ample opportunity for it to be conveyed by human intercourse. There are also innumerable instances which prove the communication of cholera, by individual cases of the disease, in the most convincing manner. Instances such as the following seem free from every source of fallacy. I called lately to inquire respecting the death of Mrs. Gore, the wife of a labourer, from cholera, at New Leigham Road, Streatham. I found that a son of deceased had been living and working at Chelsea. He came home ill with a bowel complaint, of which he died in a day or two. His death took place on August 18th. His mother, who attended on him, was taken ill on the next day, and died the day following (August 20th). There were no other deaths from cholera registered in any of the metropolitan districts, down to the 26th August, within two or three miles of the above place; the nearest being
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TL;DR: The spectrum of illness and the immunologic response produced by cholera in volunteers were studied and Titers of vibriocidal antibody rose after diarrhea, peaked the second week after challenge, and rapidly fell during the next four weeks.
Abstract: The spectrum of illness and the immunologic response produced by cholera in volunteers were studied. The strains of Vibrio cholerae used were classical Inaba 569B and classical Ogawa 395. An oral dose of 108 organisms in buffered saline was required to induce the diarrhea of cholera. When given with live organisms, NaHCO3 lowered the infecting dose from 108 to 104 organisms. Clinical manifestations of infection varied from culturally positive formed stools to "rice water" diarrhea. Severe diarrhea did not have an explosive onset but rather progressively increased in volume during a 24-hr period. In 45% of cases the stool was positive for V. cholerae before the onset of diarrhea. Titers of vibriocidal antibody rose after diarrhea, peaked the second week after challenge, and rapidly fell during the next four weeks.
317 citations
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TL;DR: A preliminary attempt to validate this model using published data on sanitation level, life expectancy, and adult literacy rates, for 65 developing countries appears to provide preliminary support for the threshold saturation theory but further empirical validation is required before a quantitative predictive model can be developed.
Abstract: A general theory on the relationship between water supply and sanitation investments and health, the threshold-saturation theory, is proposed. The theory takes into consideration three variables: health status, socioeconomic status, and sanitation level, and attempts to encompass, for the first time in one general theoretical framework, numerous conflicting empirical findings. The two-tiered S-shaped logistic form of the relationship that is proposed assumes that at the lower end of the socioeconomic spectrum there is a threshold below which investments in community water supplies and/or excreta disposal facilities alone result in little detectable improvement in health status. Similarly, at the higher end of the socioeconomic scale, it is suggested that a point of saturation is reached beyond which further significant health benefits cannot be obtained by investments in conventional community sanitation facilities.
A preliminary attempt to validate this model using published data on sanitation level (defined as access to water supply), life expectancy, and adult literacy rates, for 65 developing countries, appears to provide preliminary support for the threshold saturation theory but further empirical validation is required before a quantitative predictive model can be developed.
83 citations
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TL;DR: Results show that cholera transmission was via contaminated surface water, particularly water taken into households for cooking or drinking, and the frequency of exposure appeared to be a major determinant of the infection rate.
Abstract: The apparent failure of handpump tubewells to reduce the incidence of cholera among users in the flooded rural area of Bangladesh has stimulated interest in defining precisely the means of Vibrio cholerae transmission during localized outbreaks. Cholera-infected neighbourhoods were placed under intensive microbiological surveillance to pinpoint contaminated sources and subsequent infections. The results show that cholera transmission was via contaminated surface water, particularly water taken into households for cooking or drinking. Infections resulted from a daily dose not exceeding 105 organisms and the frequency of exposure appeared to be a major determinant of the infection rate. The importance of these data in environmental interventions and particularly in the provision of tubewells is discussed.
70 citations
"Intervention studies and the defini..." refers background in this paper
...This example is of particular interest because, through a remarkable recent microbiological-cum-epidemiologic study in Matlab (11), direct microbiologic data are available on the frequency with which V....
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...However, the microbiologic data (11) and our model indicate that improving the quality of drinking water did effect a major reduction in exposure to V....
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TL;DR: Luecke and McGinn as mentioned in this paper showed that many "no significant effect" findings may be artifacts of statistical techniques used to analyze cross-sectional survey data, and compared the statistics thus yielded with their knowledge of the causal relationships programmed into the data.
Abstract: Many studies have purported to demonstrate that schooling has little independent impact on achievement and that administrators can do little to boost students' test scores. Daniel F. Luecke and Noel F. McGinn question such results and use variations of a computer simulation model to generate data sets similar to those collected by educational researchers. They subject the data generated to several kinds of aggregation procedures and regression analysis, and compare the statistics thus yielded with their knowledge of the causal relationships programmed into the data. They conclude that many "no significant effect" findings may be artifacts of statistical techniques used to analyze cross-sectional survey data.
30 citations