Summaryobjective To assess the extent and causes of microbiological contamination of household drinking water between source and point-of-use in developing countries.methods A systematic meta-analysis of 57 studies measuring bacteria counts for source water and stored water in the home to assess how contamination varied between settings.results The bacteriological quality of drinking water significantly declines after collection in many settings. The extent of contamination after water collection varies considerably between settings, but is proportionately greater where faecal and total coliform counts in source water are low.conclusions Policies that aim to improve water quality through source improvements may be compromised by post-collection contamination. Safer household water storage and treatment is recommended to prevent this, together with point-of-use water quality monitoring.
Robert Bain and colleagues conduct a systematic review and meta-analysis to assess whether water from “improved” sources is less likely to contain fecal contamination than “unimproved” sources and find that access to an “improved source” provides a measure of sanitary protection but does not ensure water is free of fecal contamination. Please see later in the article for the Editors' Summary
ObjectivesTo estimate exposure to faecal contamination through drinking water as indicated by levels of Escherichia coli (E. coli) or thermotolerant coliform (TTC) in water sources.MethodsWe estimated coverage of different types of drinking water source based on household surveys and censuses using multilevel modelling. Coverage data were combined with water quality studies that assessed E. coli or TTC including those identified by a systematic review (n = 345). Predictive models for the presence and level of contamination of drinking water sources were developed using random effects logistic regression and selected covariates. We assessed sensitivity of estimated exposure to study quality, indicator bacteria and separately considered nationally randomised surveys.ResultsWe estimate that 1.8 billion people globally use a source of drinking water which suffers from faecal contamination, of these 1.1 billion drink water that is of at least ‘moderate’ risk (>10 E. coli or TTC per 100 ml). Data from nationally randomised studies suggest that 10% of improved sources may be ‘high’ risk, containing at least 100 E. coli or TTC per 100 ml. Drinking water is found to be more often contaminated in rural areas (41%, CI: 31%–51%) than in urban areas (12%, CI: 8–18%), and contamination is most prevalent in Africa (53%, CI: 42%–63%) and South-East Asia (35%, CI: 24%–45%). Estimates were not sensitive to the exclusion of low quality studies or restriction to studies reporting E. coli.ConclusionsMicrobial contamination is widespread and affects all water source types, including piped supplies. Global burden of disease estimates may have substantially understated the disease burden associated with inadequate water services.
When the Ras mitogen-activated protein kinase (MAPK) signaling pathway of quiescent cells is stimulated with growth factors or phorbol esters, the early response genes c-fos and c-myc are rapidly induced, and concurrently there is a rapid phosphorylation of histone H3. Using an antibody specific for phosphorylated Ser-10 of H3, we show that Ser-10 of H3 is phosphorylated, and we provide direct evidence that phosphorylated H3 is associated with c-fos and c-myc genes in stimulated cells. H3 phosphorylation may contribute to proto-oncogene induction by modulating chromatin structure and releasing blocks in elongation. Previously we reported that persistent stimulation of the Ras-MAPK signaling pathway in oncogene-transformed cells resulted in increased amounts of phosphorylated histone H1. Here we show that phosphorylated H3 is elevated in the oncogene-transformed mouse fibroblasts. Further we show that induction of ras expression results in a rapid increase in H3 phosphorylation. H3 phosphatase, identified as PP1, activities in ras-transformed and parental fibroblast cells were similar, suggesting that elevated H3 kinase activity was responsible for the increased level of phosphorylated H3 in the oncogene-transformed cells. Elevated levels of phosphorylated H1 and H3 may be responsible for the less condensed chromatin structure and aberrant gene expression observed in the oncogene-transformed cells.Histone H1 and the N-terminal tail of H3 have key roles in the folding and inter-association of the chromatin fiber (1-5). Modification of the N-and C-terminal tails of H1 by phosphorylation or the N-terminal tail of H3 by acetylation and/or phosphorylation could destabilize higher order chromatin structure (6, 7). Myc-and ras-transformed and Rb-deficient fibroblasts have a more decondensed chromatin structure than parental cells (8 -10). A general feature of these oncogenetransformed and Rb-deficient cells is increased H1 phosphorylation. H1 phosphorylation may relax chromatin by interfering with its action in chromatin folding and intermolecular fiberfiber interactions (3).Continuous stimulation of the Ras mitogen-activated protein kinase (MAPK) 1 signaling pathway in mouse fibroblasts transformed with oncogenes ras, fes, mos, and c-myc elevates the level of phosphorylated H1 (9, 11). Activation of the Ras-MAPK signaling pathway of quiescent fibroblasts treated with growth factors or phorbol esters results in the phosphorylation of H3 (12-14). Thus, persistent activation of the Ras-MAPK pathway in oncogene-transformed cells may also increase the level of phosphorylated H3, contributing to the destabilization of the higher order compaction of chromatin.The N-terminal domain of H3 can be phosphorylated on Ser-10 and/or Ser-28 (15, 16); however, the site of mitogeninduced phosphorylation remains unknown. Phosphorylation of H3 happens concurrently with the transcriptional activation of the immediate early response genes, e.g. c-fos (12, 13). However, inhibition of transcription does not prevent mitogen-activated H3 phosph...
In developing countries, the microbial contamination of household drinking water is implicated in the prevalence of various diseases. This systematic review is concerned with two health outcomes, general diarrhoea and cholera, and their relationship with water quality at point-of-use. Observational studies investigating this relationship are reviewed, as well as studies of home water treatment and storage interventions. For cholera, a clear relationship was found with contaminated water. Home water treatment and storage interventions were also found to reduce cholera. For general diarrhoea, no clear relationship was found with point-of-use water quality, although interventions did significantly reduce diarrhoeal incidence. Reasons for these apparently contradictory results concerning general diarrhoea are discussed and suggestions for further research offered. The policy implications of the findings are also discussed.
BackgroundHealth care utilization is affected by several factors including geographic accessibility. Empirical data on utilization of health facilities is important to understanding geographic accessibility and defining health facility catchments at a national level. Accurately defining catchment population improves the analysis of gaps in access, commodity needs and interpretation of disease incidence. Here, empirical household survey data on treatment seeking for fever were used to model the utilisation of public health facilities and define their catchment areas and populations in northern Namibia.MethodThis study uses data from the Malaria Indicator Survey (MIS) of 2009 on treatment seeking for fever among children under the age of five years to characterize facility utilisation. Probability of attendance of public health facilities for fever treatment was modelled against a theoretical surface of travel times using a three parameter logistic model. The fitted model was then applied to a population surface to predict the number of children likely to use a public health facility during an episode of fever in northern Namibia.ResultsOverall, from the MIS survey, the prevalence of fever among children was 17.6% CI [16.0-19.1] (401 of 2,283 children) while public health facility attendance for fever was 51.1%, [95%CI: 46.2-56.0]. The coefficients of the logistic model of travel time against fever treatment at public health facilities were all significant (p < 0.001). From this model, probability of facility attendance remained relatively high up to 180 minutes (3 hours) and thereafter decreased steadily. Total public health facility catchment population of children under the age five was estimated to be 162,286 in northern Namibia with an estimated fever burden of 24,830 children. Of the estimated fevers, 8,021 (32.3%) were within 30 minutes of travel time to the nearest health facility while 14,902 (60.0%) were within 1 hour.ConclusionThis study demonstrates the potential of routine household surveys to empirically model health care utilisation for the treatment of childhood fever and define catchment populations enhancing the possibilities of accurate commodity needs assessment and calculation of disease incidence. These methods could be extended to other African countries where detailed mapping of health facilities exists.
Using three independent approaches, we studied the effects of H-ras on metastasis formation. Analysis of five in vitro-ras-transfected 1OT1/2 clones with either flat or refractile morphologies revealed a relationship between metastatic potential, H-ras expression, and anchorage-independent growth. Four metastatic variants derived from a poorly metastatic, low-H-ras-expressing line all expressed high levels of H-ras RNA and grew efficiently in soft agar. Activation of H-ras expression in the metastatic tumors had occurred through amplification and rearrangement of H-ras sequences. In addition, preinduction of p21 synthesis in NIH 3T3 line 433, which contains v-H-ras under transcriptional control of the glucocorticoid-sensitive mouse mammary tumor virus long terminal repeat, significantly increased metastatic efficiency. Glucocorticoid treatment of normal or pEJ-transformed NIH 3T3 cells did not affect metastatic potential. These data reveal a direct relationship between ras expression and metastasis formation and suggest that metastatic and transformed phenotypes may be coregulated in ras-transformed 10TI/2 and NIH 3T3 cells.Tumor progression is the tendency of tumors to become more aggressive with time. The widely accepted model is that described originally by Foulds (11), in which progression was characterized by emergence of new variants with a selective advantage for growth in the host. Metastatic spread is the most important form of tumor progression because it is the most life-threatening aspect of the disease. Metastasis is a complex process involving invasion through host barriers into the vasculature and survival against circulating host immune defenses, followed by implantation, extravasation, and growth at sites distant to the primary neoplasm (24,25,27,34).Much effort has been directed at understanding the metastatic cascade, yet little is known about the mechanisms involved. On the other hand, the critical events in cell immortalization and transformation have been partially elucidated and attributed to mutation or disregulation of a group of genes collectively known as oncogenes. These genes are normally responsible for maintenance of control over diverse cellular functions including proliferation, differentiation, morphological regulation, communication, and motility (3,20,22,33,40). Consequently, they are good candidates for study of the metastatic process, which also requires alterations of many of these functions (24,27,34).Recent studies showed that primary and established rodent fibroblasts transformed by activated ras sequences can form metastases (12,18,23,27,36). Exclusive selection and analysis of in vitro-transformed foci, however, raises the possibility that ras transformation may be a permissive event for expression of the metastatic phenotype but may not be directly involved. To resolve this question we analyzed the relationship between ras expression and metastatic poten-* Corresponding author.tial. ras-mediated transformation may be the initial event which allows expression of second...
BackgroundAccess to safe drinking water is essential for health. Monitoring access to drinking water focuses on water supply type at the source, but there is limited evidence on whether quality differences at the source persist in water stored in the household.ObjectivesWe assessed the extent of fecal contamination at the source and in household stored water (HSW) and explored the relationship between contamination at each sampling point and water supply type.MethodsWe performed a bivariate random-effects meta-analysis of 45 studies, identified through a systematic review, that reported either the proportion of samples free of fecal indicator bacteria and/or individual sample bacteria counts for source and HSW, disaggregated by supply type.ResultsWater quality deteriorated substantially between source and stored water. The mean percentage of contaminated samples (noncompliance) at the source was 46% (95% CI: 33, 60%), whereas mean noncompliance in HSW was 75% (95% CI: 64, 84%). Water supply type was significantly associated with noncompliance at the source (p < 0.001) and in HSW (p = 0.03). Source water (OR = 0.2; 95% CI: 0.1, 0.5) and HSW (OR = 0.3; 95% CI: 0.2, 0.8) from piped supplies had significantly lower odds of contamination compared with non-piped water, potentially due to residual chlorine.ConclusionsPiped water is less likely to be contaminated compared with other water supply types at both the source and in HSW. A focus on upgrading water services to piped supplies may help improve safety, including for those drinking stored water.CitationShields KF, Bain RE, Cronk R, Wright JA, Bartram J. 2015. Association of supply type with fecal contamination of source water and household stored drinking water in developing countries: a bivariate meta-analysis. Environ Health Perspect 123:1222–1231; http://dx.doi.org/10.1289/ehp.1409002
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