Temporal trend in diarrhea prevalence in children 8–32 months of age.

<p>Temporal trend in diarrhea prevalence in children 8–32 months of age.</p

Causal chain between upgrading from intermittent to continuous water supply and reduction in waterborne illness.

<p>Upgrading from intermittent to continuous water supply is expected to be associated with reduced waterborne illness through improved tap water quality and increased water availability, which, in turn, is expected to eliminate household storage of drinking water, reduce water use from unsafe nonmunicipal sources, and improve hygiene practices.</p

Flowchart of study participation.

<p>Flowchart of study participation.</p

Temporal trend in percentage of stored water samples with <i>E</i>. <i>coli</i> >10 CFU/100 mL.

<p>Temporal trend in percentage of stored water samples with <i>E</i>. <i>coli</i> >10 CFU/100 mL.</p

Upgrading a Piped Water Supply from Intermittent to Continuous Delivery and Association with Waterborne Illness: A Matched Cohort Study in Urban India

<div><p>Background</p><p>Intermittent delivery of piped water can lead to waterborne illness through contamination in the pipelines or during household storage, use of unsafe water sources during intermittencies, and limited water availability for hygiene. We assessed the association between continuous versus intermittent water supply and waterborne diseases, child mortality, and weight for age in Hubli-Dharwad, India.</p><p>Methods and Findings</p><p>We conducted a matched cohort study with multivariate matching to identify intermittent and continuous supply areas with comparable characteristics in Hubli-Dharwad. We followed 3,922 households in 16 neighborhoods with children <5 y old, with four longitudinal visits over 15 mo (Nov 2010–Feb 2012) to record caregiver-reported health outcomes (diarrhea, highly credible gastrointestinal illness, bloody diarrhea, typhoid fever, cholera, hepatitis, and deaths of children <2 y old) and, at the final visit, to measure weight for age for children <5 y old. We also collected caregiver-reported data on negative control outcomes (cough/cold and scrapes/bruises) to assess potential bias from residual confounding or differential measurement error.</p><p>Continuous supply had no significant overall association with diarrhea (prevalence ratio [PR] = 0.93, 95% confidence interval [CI]: 0.83–1.04, <i>p</i> = 0.19), bloody diarrhea (PR = 0.78, 95% CI: 0.60–1.01, <i>p</i> = 0.06), or weight-for-age z-scores (Δz = 0.01, 95% CI: −0.07–0.09, <i>p</i> = 0.79) in children <5 y old. In prespecified subgroup analyses by socioeconomic status, children <5 y old in lower-income continuous supply households had 37% lower prevalence of bloody diarrhea (PR = 0.63, 95% CI: 0.46–0.87, <i>p</i>-value for interaction = 0.03) than lower-income intermittent supply households; in higher-income households, there was no significant association between continuous versus intermittent supply and child diarrheal illnesses. Continuous supply areas also had 42% fewer households with ≥1 reported case of typhoid fever (cumulative incidence ratio [CIR] = 0.58, 95% CI: 0.41–0.78, <i>p</i> = 0.001) than intermittent supply areas. There was no significant association with hepatitis, cholera, or mortality of children <2 y old; however, our results were indicative of lower mortality of children <2 y old (CIR = 0.51, 95% CI: 0.22–1.07, <i>p</i> = 0.10) in continuous supply areas. The major limitations of our study were the potential for unmeasured confounding given the observational design and measurement bias from differential reporting of health symptoms given the nonblinded treatment. However, there was no significant difference in the prevalence of the negative control outcomes between study groups that would suggest undetected confounding or measurement bias.</p><p>Conclusions</p><p>Continuous water supply had no significant overall association with diarrheal disease or ponderal growth in children <5 y old in Hubli-Dharwad; this might be due to point-of-use water contamination from continuing household storage and exposure to diarrheagenic pathogens through nonwaterborne routes. Continuous supply was associated with lower prevalence of dysentery in children in low-income households and lower typhoid fever incidence, suggesting that intermittently operated piped water systems are a significant transmission mechanism for <i>Salmonella typhi</i> and dysentery-causing pathogens in this urban population, despite centralized water treatment. Continuous supply was associated with reduced transmission, especially in the poorer higher-risk segments of the population.</p></div

Categories of <i>E</i>. <i>coli</i> counts in stored water across arms (see S6 Table).

<p>Categories of <i>E</i>. <i>coli</i> counts in stored water across arms (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121907#pone.0121907.s012" target="_blank">S6 Table</a>).</p

Categories of <i>E</i>. <i>coli</i> counts in tubewell water across arms (see S6 Table).

<p>Categories of <i>E</i>. <i>coli</i> counts in tubewell water across arms (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121907#pone.0121907.s012" target="_blank">S6 Table</a>).</p

Uptake indicators in intervention groups (cumulative data from 10 follow-up visits).

<p>^a Index children 6–18 mo of age at enrollment.</p><p>^b Older siblings 19–60 mo of age at enrollment.</p><p>Uptake indicators in intervention groups (cumulative data from 10 follow-up visits).</p

Serological Measures of Malaria Transmission in Haiti: Comparison of Longitudinal and Cross-Sectional Methods

<div><p>Background</p><p>Efforts to monitor malaria transmission increasingly use cross-sectional surveys to estimate transmission intensity from seroprevalence data using malarial antibodies. To date, seroconversion rates estimated from cross-sectional surveys have not been compared to rates estimated in prospective cohorts. Our objective was to compare seroconversion rates estimated in a prospective cohort with those from a cross-sectional survey in a low-transmission population.</p><p>Methods and Findings</p><p>The analysis included two studies from Haiti: a prospective cohort of 142 children ages ≤11 years followed for up to 9 years, and a concurrent cross-sectional survey of 383 individuals ages 0–90 years old. From all individuals, we analyzed 1,154 blood spot specimens for the malaria antibody MSP-1₁₉ using a multiplex bead antigen assay. We classified individuals as positive for malaria using a cutoff derived from the mean plus 3 standard deviations in antibody responses from a negative control set of unexposed individuals. We estimated prospective seroconversion rates from the longitudinal cohort based on 13 incident seroconversions among 646 person-years at risk. We also estimated seroconversion rates from the cross-sectional survey using a reversible catalytic model fit with maximum likelihood. We found the two approaches provided consistent results: the seroconversion rate for ages ≤11 years was 0.020 (0.010, 0.032) estimated prospectively versus 0.023 (0.001, 0.052) in the cross-sectional survey.</p><p>Conclusions</p><p>The estimation of seroconversion rates using cross-sectional data is a widespread and generalizable problem for many infectious diseases that can be measured using antibody titers. The consistency between these two estimates lends credibility to model-based estimates of malaria seroconversion rates using cross-sectional surveys. This study also demonstrates the utility of including malaria antibody measures in multiplex assays alongside targets for vaccine coverage and other neglected tropical diseases, which together could comprise an integrated, large-scale serological surveillance platform.</p></div

Temporal trend in percentage of stored water samples with <i>E</i>. <i>coli</i> >100 CFU/100 mL.

<p>Temporal trend in percentage of stored water samples with <i>E</i>. <i>coli</i> >100 CFU/100 mL.</p