Waterborne transmission of protozoan parasites: Review of worldwide outbreaks - An update 2011-2016.

Typhoid and paratyphoid fever continue to be important causes of illness and death, particularly among children and adolescents in south-central and Southeast Asia, where enteric fever is associated with poor sanitation and unsafe food and water. High-quality incidence data from Asia are underpinning efforts to expand access to typhoid vaccines. Efforts are underway to develop vaccines that are immunogenic in infants after a single dose and that can be produced locally in countries of endemicity. The growing importance of Salmonella enterica serotype Paratyphi A in Asia is concerning. Antimicrobial resistance has sequentially emerged to traditional first-line drugs, fluoroquinolones, and third-generation cephalosporins, posing patient treatment challenges. Azithromycin has proven to be an effective alternative for treatment of uncomplicated typhoid fever. The availability of full genome sequences for S. enterica serotype Typhi and S. enterica serotype Paratyphi A confirms their place as monomorphic, human-adapted pathogens vulnerable to control measures if international efforts can be redoubled.

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Global trends in typhoid and paratyphoid fever

https://www.communityledtotalsanitation.org/sites/communityledtotalsanitation.org/files/Tropical_enteropathy_Humphreys.pdf

Child undernutrition, tropical enteropathy, toilets, and handwashing

Many climate change adaptation efforts aim to address the implications of potential changes in the frequency, intensity, and duration of weather and climate events that affect the risk of extreme impacts on human society That risk is determined not only by the climate and weather events (the hazards) but also by the exposure and vulnerability to these hazards Therefore, effective adaptation and disaster risk management strategies and practices also depend on a rigorous understanding of the dimensions of exposure and vulnerability, as well as a proper assessment of changes in those dimensions This chapter aims to provide that understanding and assessment, by further detailing the determinants of risk as presented in Chapter 1 

The first sections of this chapter elucidate the concepts that are needed to define and understand risk, and show that risk originates from a combination of social processes and their interaction with the environment (Sections 22 and 23), and highlight the role of coping and adaptive capacities (Section 24) The following section (25) describes the different dimensions of vulnerability and exposure as well as trends therein Given that exposure and vulnerability are highly context-specific, this section is by definition limited to a general overview (a more quantitative perspective on trends is provided in Chapter 4) A methodological discussion (Section 26) of approaches to identify and assess risk provides indications of how the dimensions of exposure and vulnerability can be explored in specific contexts, such as adaptation planning, and the central role of risk perception and risk communication The chapter concludes with a cross-cutting discussion of risk accumulation and the nature of disasters

/pdf/determinants-of-risk-exposure-and-vulnerability-36vj51sbnp.pdf

Determinants of risk: Exposure and vulnerability

Background Ever since John Snow’s intervention on the Broad St pump, the effect of water quality, hygiene and sanitation in preventing diarrhoea deaths has always been debated. The evidence identified in previous reviews is of variable quality, and mostly relates to morbidity rather than mortality.

Methods We drew on three systematic reviews, two of them for the Cochrane Collaboration, focussed on the effect of handwashing with soap on diarrhoea, of water quality improvement and of excreta disposal, respectively. The estimated effect on diarrhoea mortality was determined by applying the rules adopted for this supplement, where appropriate.

Results The striking effect of handwashing with soap is consistent across various study designs and pathogens, though it depends on access to water. The effect of water treatment appears similarly large, but is not found in few blinded studies, suggesting that it may be partly due to the placebo effect. There is very little rigorous evidence for the health benefit of sanitation; four intervention studies were eventually identified, though they were all quasi-randomized, had morbidity as the outcome, and were in Chinese.

Conclusion We propose diarrhoea risk reductions of 48, 17 and 36%, associated respectively, with handwashing with soap, improved water quality and excreta disposal as the estimates of effect for the LiST model. Most of the evidence is of poor quality. More trials are needed, but the evidence is nonetheless strong enough to support the provision of water supply, sanitation and hygiene for all.

/pdf/water-sanitation-and-hygiene-for-the-prevention-of-diarrhoea-3v616xqhcg.pdf

Water, sanitation and hygiene for the prevention of diarrhoea.

Objective To assess the effectiveness of interventions to improve the microbial quality of drinking water for preventing diarrhoea Design Systematic review Data sources Cochrane Infectious Diseases Group9s trials register, CENTRAL, Medline, Embase, LILACS; hand searching; and correspondence with experts and relevant organisations Study selection Randomised and quasirandomised controlled trials of interventions to improve the microbial quality of drinking water for preventing diarrhoea in adults and in children in settings with endemic disease Data extraction Allocation concealment, blinding, losses to follow-up, type of intervention, outcome measures, and measures of effect Pooled effect estimates were calculated within the appropriate subgroups Data synthesis 33 reports from 21 countries documenting 42 comparisons were included Variations in design, setting, and type and point of intervention, and variations in defining, assessing, calculating, and reporting outcomes limited the comparability of study results and pooling of results by meta-analysis In general, interventions to improve the microbial quality of drinking water are effective in preventing diarrhoea Effectiveness was not conditioned on the presence of improved water supplies or sanitation in the study setting and was not enhanced by combining the intervention with instructions on basic hygiene, a water storage vessel, or improved sanitation or water supplies—other common environmental interventions intended to prevent diarrhoea Conclusion Interventions to improve water quality are generally effective for preventing diarrhoea in all ages and in under 5s Significant heterogeneity among the trials suggests that the level of effectiveness may depend on a variety of conditions that research to date cannot fully explain

https://www.bmj.com/content/bmj/334/7597/782.full.pdf

Taber Rabie

Papers

Interventions to improve water quality for preventing diarrhoea: systematic review and meta-analysis