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Biomedical subjects

R G Feachem

Publications and source records attributed to R G Feachem.

At least 55 records · Page 3Linked to original sources
PubMed1985

Interventions for the control of diarrhoeal diseases among young children: improving water supplies and excreta disposal facilities.

A theoretical model is proposed that relates the level of ingestion of diarrhoea-causing pathogens to the frequency of diarrhoea in the community. The implications of this model are that, in poor communities with inadequate water supply and excreta disposal, reducing the level of enteric pathogen ingestion by a given amount will have a greater impact on diarrhoea mortality rates than on morbidity rates, a greater impact on the incidence rate of severe diarrhoea than on that of mild diarrhoea, and a greater impact on diarrhoea caused by pathogens having high infectious doses than on diarrhoea caused by pathogens of a low infectious dose. The impact of water supply and sanitation on diarrhoea, related infections, nutritional status, and mortality is analysed by reviewing 67 studies from 28 countries. The median reductions in diarrhoea morbidity rates are 22% from all studies and 27% from a few better-designed studies. All studies of the impact on total mortality rates show a median reduction of 21%, while the few better-designed studies give a median reduction of 30%. Improvements in water quality have less of an impact than improvements in water availability or excreta disposal.

Child↗
PubMed1985

Interventions for the control of diarrhoeal diseases among young children: prevention of low birth weight.

The effect of low birth weight (LBW) on diarrhoea morbidity and mortality is analysed and interventions to increase birth weights are reviewed. Birth weight is a major determinant of infant mortality and, in developed countries at least, its effect on neonatal mortality is independent of socioeconomic status. We have located no satisfactory data on LBW as a determinant of diarrhoea mortality or morbidity. The strong association between LBW and mortality, however, makes it likely that there is an association between LBW and diarrhoea mortality in developing countries where diarrhoea is a major cause of infant death. Poor maternal nutrition, certain infections, pre-eclampsia, arduous work after mid-pregnancy, short birth intervals, and teenage pregnancy are likely to be causally associated with LBW in developing countries. Tobacco and alcohol consumption are additional risk factors.Of the interventions examined, maternal food supplementation has been the most studied. If targeted to mothers at nutritional risk, and if the food is consumed in addition to the usual diet, the prevalence of LBW can be expected to be reduced. However, food supplementation can be expensive and the results from carefully supervised feeding trials may be better than those that can be achieved in national programmes. The effect of supplementation with iron, zinc or folate requires further study. If it were possible to intervene in maternal nutrition, health and life-style in a developing country in a way that reduced the prevalence of LBW from around 30% to around 15%, a fall in the infant mortality rate of around 26% would be expected. The fall in infant diarrhoea mortality rate might be similar. The scarce data on relative risk of morbidity by birth weight do not allow any comparable computations for morbidity reductions to be made.This review confirms that whatever its association with diarrhoea, LBW is an important determinant of infant mortality. For the more general goal of reducing infant mortality it is necessary to know more about the nature, etiology, and prevention of LBW in developing countries.

Alcohol Drinking↗
PubMed1985

Interventions for the control of diarrhoeal diseases among young children: chemoprophylaxis.

A number of situations place young children at increased risk of diarrhoea. Among these, the best documented in developing countries is contact with a diarrhoea case in a family or household. The most common application of chemoprophylaxis in developing countries is to prevent cholera or shigellosis among household contacts of known cases. There is little evidence that chemoprophylaxis is effective in reducing diarrhoea morbidity and mortality, except perhaps in travellers. Theoretical calculations in this paper (based on optimistic assumptions) suggest that chemoprophylaxis of household contacts of known cholera cases in Bangladesh might reduce overall diarrhoea incidence rates in children under 5 years of age by 0.02-0.06% and diarrhoea mortality rates by 0.4-1.2%. Chemoprophylaxis of household contacts of known shigellosis cases might reduce overall diarrhoea incidence rates by 0.15-0.35% and diarrhoea mortality rates by 0.3-0.7% in the same age group. The correct identification of index cases of cholera and shigellosis, followed by the rapid distribution of drugs to their household contacts, requires skills and resources that are scarce in the developing countries. Chemoprophylaxis can contribute to the widespread emergence and dissemination of antimicrobial resistance. The available evidence suggests that chemoprophylaxis is not feasible in many settings and that, even if successfully implemented, it is not a cost-effective intervention for national diarrhoeal diseases control programmes.

Child, Preschool↗
PubMed1984

Response of toxigenic Vibrio cholerae 01 to physico-chemical stresses in aquatic environments.

The survival and growth of toxigenic Vibrio cholerae 01 in water under various conditions of salinity, pH, temperature and cation composition and concentration were studied in an extensive series of laboratory experiments. Inter- and intra-strain variation in stress response (of 01 and non-01 strains) and the ability of V. cholerae to adapt to stressful environments were also studied. Toxigenic V. cholerae 01 were able to survive for at least 70 days at 25 degrees C in solutions of sea salt. The optimal salt concentration was 2.0% though all solutions in the range 0.25-3.0% gave good support. Substrains with enhanced capacity to persist at sub-optimal salinity (0.1%) were demonstrated. A great degree of inter-strain variation in stress response at low salinity (0.05%) was found among 59 strains, and this variation was unrelated to serogroup (01 or non-01), source (clinical or environmental) or country of origin (Tanzania or Bangladesh). At optimal salinity, inter-strain variation was less and 18 out of 20 strains remained viable at high concentrations for at least 40 months at 25 degrees C. V. cholerae 01 could not survive beyond 45 days at 4 degrees C and optimal salinity, either with or without nutrients. The optimal pH range for survival at 25 degrees C was 7.0-8.5 at optimal salinity, and 7.5-9.0 at low salinity. V. cholerae 01 require Na+ for survival in the absence of nutrients, and for enhanced growth in their presence. The presence of Ca2+ or Mg2+, in addition to Na+, further enhanced survival. These, and other results reported in this paper, suggest that toxigenic V. cholerae 01 are able to survive for extended periods in warm water containing no nutrients but having a salinity of 0.25-3.0% and a pH of around 8.0. With added nutrients and under the same conditions, rapid growth is possible. The implications of these findings for the identification of putative aquatic reservoirs of V. cholerae 01, and for the epidemiology of cholera, are considerable.

Culture Media↗
PubMed1983

Excreta disposal facilities and intestinal parasitism in urban Africa: preliminary studies in Botswana, Ghana and Zambia.

The relationships between intestinal parasitism and excreta disposal technologies in Gaborone (Botswana), Ndola (Zambia) and Kumasi (Ghana) were investigated. Parasitic prevalence and intensity rates amongst groups of urban residents having similar socio-economic status and housing, but different excreta disposal technologies, were compared. In Gaborone, there was no evidence of a difference in intestinal parasitism between those using aqua privies and having access to public taps and those in identical houses enjoying flush toilets, in-house water connections and showers. In Ndola, the group with sewered aqua privies had larger houses, cleaner toilets, better water supplies, longer residence and more people in paid employment than the groups using pit latrines or communal flush toilets. Despite this, the sewered aqua privy users were not found to be different from the other groups with regard to hookworm and protozoal infection but had significantly higher Ascaris infection rates. In Kumasi, despite the differences in toilet type--from squalid communal aqua privies, through often fouled bucket latrines to well-maintained flush toilet systems--and despite also the differences in water provision, no evidence was obtained of any differences in intestinal parasitism between the groups studied. These findings suggest that the provision of superior water and sanitation facilities to a small cluster of houses, or to houses scattered through an area, may not protect those families from infection if the over-all level of faecal contamination of the environment is high. The sample sizes and response rates achieved in this study were low and follow-up studies, employing the same methodology but with larger samples, are recommended.

Adolescent↗
PubMed1983

Measuring the impact of water supply and sanitation investments on diarrhoeal diseases: problems of methodology.

A review of the published literature on the impact of water supply and/or excreta disposal facilities on diarrhoeal diseases, or on infections related to diarrhoea, reveals several methodological problems that hamper the drawing of definitive conclusions from these studies. This paper examines eight of these methodological problems: lack of adequate control, the one to one comparison, confounding variables, health indicator recall, health indicator definition, failure to analyse by age, failure to record usage, and the seasonality of impact variables. It is suggested that an evaluation of the impact on health of environmental interventions may best be undertaken by the combined efforts of engineers, social scientists and epidemiologists in 'opportunistic' settings and that the intervening behavioural processes so necessary for health impact to occur should be a primary focus of such evaluations.

Age Factors↗
PubMed1980

Rural water and sanitation. Community participation in appropriate water supply and sanitation technologies: the mythology for the Decade.

The International Drinking Water Supply and Sanitation Decade (1981-90) is almost upon us. During this period, massive international efforts will be made to accelerate the provision of domestic water supply and sanitation facilities for the rural population of developing countries. Certain concepts and approaches are being developed and promoted as guiding themes that will help to steer and coordinate the activities of the Decade. Among them are 'appropriate technology' 'community participation' and a 'village level' or 'user-choice' approach. The validity and importance of these concepts are discussed. It is concluded that these concepts are often applied in an over-simplified manner and that they divert attention away from the fundamental political and administrative realities that primarily determine the success or failure of rural water and sanitation programmes.

Community Participation↗