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Journal ArticleDOI

Intervention studies and the definition of dominant transmission routes

01 Sep 1984-American Journal of Epidemiology (Oxford University Press)-Vol. 120, Iss: 3, pp 449-455
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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Journal ArticleDOI
TL;DR: Fecal contamination of compounds in low-income neighborhoods of urban Maputo, Mozambique is assessed using a set of MST assays that were validated with animal stool and latrine sludge from study compounds and associations with risk factors were generally weak and often differed in direction between different targets and sample types.

49 citations

Journal ArticleDOI
P.J. Kolsky1
TL;DR: The application of epidemiological understanding of diarrhoeal disease to interventions in water and sanitation and historical and recent perceptions of water, sanitation, and diarrhoale disease are reviewed.
Abstract: This paper reviews the application of epidemiological understanding of diarrhoeal disease to interventions in water and sanitation. Over the past 20 years, great efforts have been made to elucidate the relationships between water supply, sanitation and diarrhoeal disease. At the outset, it was hoped that improved understanding of these relations could provide a rational framework for the planning of public health engineering interventions. This paper also reviews historical and recent perceptions of water, sanitation, and diarrhoeal disease, and summarizes progress to date. On the one hand, some fundamental ideas about the relative importance of water quality and quantity in the transmission of diarrhoeal disease have changed, and there is increased recognition of the complex interrelationships between interventions, hygiene behaviour and health. On the other hand, our understanding of the impact of interventions is painfully incomplete, and is unlikely to improve dramatically in the near future. While further research can usefully illustrate a variety of interactions in specific contexts, globally applicable planning guidelines and design criteria appear a dangerous will-o'-the-wisp. While we know more than ever before about water, sanitation and diarrhoea, much remains unknown, and is perhaps unknowable.

47 citations

Journal ArticleDOI
TL;DR: The here proposed Faecal Contamination Index is a first attempt to estimate the level of faecal contamination in communities, as much of the world's population currently lives in faecally contaminated environments as indicated by low community sanitation coverage.

44 citations

Journal ArticleDOI
TL;DR: The suggested systematization of the sanitation systems effects in each step of their implementation is an advance considering the association between the fundamental elements for formulating a planning model for sanitation infrastructure.
Abstract: The understanding of sanitation infrastructure, public health, and environmental relations is a fundamental assumption for planning sanitation infrastructure in urban areas. This article thus suggests elements for developing a planning model for sanitation infrastructure. The authors performed a historical survey of environmental and public health issues related to the sector, an analysis of the conceptual frameworks involving public health and sanitation systems, and a systematization of the various effects that water supply and sanitation have on public health and the environment. Evaluation of these effects should guarantee the correct analysis of possible alternatives, deal with environmental and public health objectives (the main purpose of sanitation infrastructure), and provide the most reasonable indication of actions. The suggested systematization of the sanitation systems effects in each step of their implementation is an advance considering the association between the fundamental elements for formulating a planning model for sanitation infrastructure.

42 citations


Cites background from "Intervention studies and the defini..."

  • ...Estudando as várias vias de contaminação de doenças, como no caso das diarréias e da incidência de cólera, Briscoe (1984, 1987) desenvolveu um modelo para a compreensão do efeito obtido após a eliminação de apenas parte das múltiplas vias de transmissão de uma determinada doença....

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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

1,203 citations

Journal ArticleDOI
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

Journal Article
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

Journal Article
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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Journal ArticleDOI
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