Helen Risebro

Quantitative Microbial Risk Assessment of Cryptosporidiosis and Giardiasis from Very Small Private Water Supplies

This article reports a quantitative microbial risk assessment of the risk of Giardia and Cryptosporidium in very small private water supplies. Both pathogens have been implicated in causing outbreaks of waterborne disease associated with such supplies, though the risk of endemic disease is not known. For exposure assessments, we used existing data to derive regression equations describing the relationships between the concentration of these pathogens and Escherichia coli in private water supplies. Pathogen concentrations were then estimated using national surveillance data of E. coli in private water supplies in England and France. The estimated risk of infection was very high with the median annual risk being of the order of 25-28% for Cryptosporidium and 0.4% to 0.7% for Giardia, though, in the poorer quality supplies the risk could be much higher. These risks are substantially greater than for public water supplies and well above the risk considered tolerable. The observation that observed infection rates are generally much lower may indicate increased immunity in people regularly consuming water from private supplies. However, this increased immunity is presumed to derive from increased disease risk in young children, the group most at risk from severe disease.

Contaminated Small Drinking Water Supplies and Risk of Infectious Intestinal Disease: A Prospective Cohort Study

Background This study sought to identify whether elevated risk of infectious intestinal disease (IID) exists in contaminated small water supply consumers compared with consumers drinking from small supplies complying with current standards and whether this effect is modified by age. Methodology and Principal Findings A prospective cohort study of 611 individuals receiving small supplies in England was conducted. Water supplies received sanitary inspection and examination for indicator bacteria and participants maintained a daily record of IID. Regression modeling with generalized estimating equations that included interaction terms between age and indicators of fecal pollution was performed. Crude IID prevalence was 9·3 days with symptoms/1000 person days (95%CI: 8·4, 10·1) and incidence was 3·2 episodes/1000 person days (95%CI, 2·7, 3·7) or 1·2 episodes per person year. Although there was no overall association between IID risk and indicator presence, there was strong interaction between age and indicator presence. In children under ten, relative risk (RR) of IID in those drinking from enterococci contaminated supplies was 4.8 (95%CI: 1.5, 15.3) for incidence and 8.9 (95%CI: 2.8, 27.5) for prevalence. In those aged 10 to 59, IID risk was lower but not statistically significant. Conclusions Contaminated small water supplies pose a substantial risk of IID to young children who live in homes reliant on these supplies. By contrast older children and adults do not appear to be at increased risk. Health care professionals with responsibility for children living in homes provided by very small water supplies should make parents aware of the risk.

Impact of the Provision of Safe Drinking Water on School Absence Rates in Cambodia: A Quasi-Experimental Study

Background Education is one of the most important drivers behind helping people in developing countries lift themselves out of poverty. However, even when schooling is available absenteeism rates can be high. Recently interest has focussed on whether or not WASH interventions can help reduce absenteeism in developing countries. However, none has focused exclusively on the role of drinking water provision. We report a study of the association between absenteeism and provision of treated water in containers into schools. Methods and Findings We undertook a quasi-experimental longitudinal study of absenteeism rates in 8 schools, 4 of which received one 20 L container of treated drinking water per day. The water had been treated by filtration and ultraviolet disinfection. Weekly absenteeism rates were compared across all schools using negative binomial model in generalized estimating equations. There was a strong association with provision of free water and reduced absenteeism (Incidence rate ratio = 0.39 (95% Confidence Intervals 0.27–0.56)). However there was also a strong association with season (wet versus dry) and a significant interaction between receiving free water and season. In one of the intervention schools it was discovered that the water supplier was not fulfilling his contract and was not delivering sufficient water each week. In this school we showed a significant association between the number of water containers delivered each week and absenteeism (IRR = 0.98 95%CI 0.96–1.00). Conclusion There appears to be a strong association between providing free safe drinking water and reduced absenteeism, though only in the dry season. The mechanism for this association is not clear but may in part be due to improved hydration leading to improved school experience for the children.

Cognitive bias modification for social anxiety in adults who stutter: a feasibility study of a randomised controlled trial

Objective To determine the feasibility and acceptability of a computerised treatment for social anxiety disorder for adults who stutter including identification of recruitment, retention and completion rates, large cost drivers and selection of most appropriate outcome measure(s) to inform the design of a future definitive trial. Design Two-group parallel design (treatment vs placebo), double-blinded feasibility study. Participants: 31 adults who stutter. Intervention Attention training via an online probe detection task in which the stimuli were images of faces displaying neutral and disgusted expressions. Main outcome measures Psychological measures: Structured Clinical Interview Global Assessment of Functioning score; Liebowitz Social Anxiety Scale; Social Phobia and Anxiety Inventory; State-Trait Anxiety Inventory; Unhelpful Thoughts and Beliefs about Stuttering. Speech fluency: percent syllables stuttered. Economic evaluation: resource use questionnaire; EuroQol three-dimension questionnaire. Acceptability: Likert Scale questionnaire of experience of trial, acceptability of the intervention and randomisation procedure. Results Feasibility of recruitment strategy was demonstrated. Participant feedback indicated that the intervention and definitive trial, including randomisation, would be acceptable to adults who stutter. Of the 31 participants who were randomised, 25 provided data at all three data collection points. Conclusions The feasibility study informed components of the intervention. Modifications to the design are needed before a definitive trial can be undertaken. Trial registration number I SRCTN55065978; Post-results.

Impact of the Provision of Safe Drinking Water on School Absence Rates in Cambodia: A Quasi-Experimental Study.

Background: Education is one of the most important drivers for helping people in developing countries lift themselves out of poverty. However, even when schooling is available absenteeism rates can be high. Recently, focus is being given on whether or not WASH interventions can help reduce absenteeism in developing countries. However, none has focused exclusively on the role of drinking water provision. We report a study on the association between absenteeism and provision of treated water in containers maintained in schools. Methods and Findings: We undertook a quasi-experimental longitudinal study of absenteeism rates in 8 schools, 4 of which received one 20 l container of treated drinking water per day. The water had been treated by filtration and ultraviolet disinfection. Weekly absenteeism rates were compared across all schools using the negative binomial model in generalized estimating equations. There was a strong association between the provision of free water and reduced absenteeism (Incidence rate ratio = 0.39 (95% confidence intervals 0.27-0.56)). However, there was also a strong association with season (wet versus dry) and a significant interaction between receiving free water and season. In one of the intervention schools, it was discovered that the water supplier was not fulfilling his contract and was not delivering sufficient water each week. In this school, we showed a significant association between the number of water containers delivered each week and absenteeism (IRR = 0.98 95% CI 0.96-1.00). Conclusion: There appears to be a strong association between providing free and safe drinking water and reduced absenteeism, although only in the dry season. The mechanism for this association is not clear but may be in part due to improved hydration leading to improved school experience for the children.