The Interaction of Deworming, Improved Sanitation, and Household Flooring with Soil-Transmitted Helminth Infection in Rural Bangladesh

<div><p>Background</p><p>The combination of deworming and improved sanitation or hygiene may result in greater reductions in soil-transmitted helminth (STH) infection than any single intervention on its own. We measured STH prevalence in rural Bangladesh and assessed potential interactions among deworming, hygienic latrines, and household finished floors.</p><p>Methodology</p><p>We conducted a cross-sectional survey (n = 1,630) in 100 villages in rural Bangladesh to measure three exposures: self-reported deworming consumption in the past 6 months, access to a hygienic latrine, and household flooring material. We collected stool samples from children 1–4 years, 5–12 years, and women 15–49 years. We performed mini-FLOTAC on preserved stool samples to detect <i>Ascaris lumbricoides</i>, <i>Enterobius vermicularis</i>, hookworm, and <i>Trichuris trichiura</i> ova. Approximately one-third (32%) of all individuals and 40% of school-aged children had an STH infection. Less than 2% of the sample had moderate/heavy intensity infections. Deworming was associated with lower <i>Ascaris</i> prevalence (adjusted prevalence ratio (PR) = 0.53; 95% CI 0.40, 0.71), but there was no significant association with hookworm (PR = 0.93, 95% CI 0.60, 1.44) or <i>Trichuris</i> (PR = 0.90, 95% CI 0.74, 1.08). PRs for hygienic latrine access were 0.91 (95% CI 0.67,1.24), 0.73 (95% CI 0.43,1.24), and 1.03 (95% CI 0.84,1.27) for <i>Ascaris</i>, hookworm, and <i>Trichuris</i>, respectively. Finished floors were associated with lower <i>Ascaris</i> prevalence (PR = 0.56, 95% CI 0.32, 0.97) but not associated with hookworm (PR = 0.48 95% CI 0.16,1.45) or <i>Trichuris</i> (PR = 0.98, 95% CI 0.72,1.33). Across helminths and combinations of exposures, adjusted prevalence ratios for joint exposures were consistently more protective than those for individual exposures.</p><p>Conclusions</p><p>We found moderate STH prevalence in rural Bangladesh among children and women of childbearing age. This study is one of the first to examine independent and combined associations with deworming, sanitation, and hygiene. Our results suggest that coupling deworming with sanitation and flooring interventions may yield more sustained reductions in STH prevalence.</p></div

Helminth infection prevalence by age, helminth, and infection intensity.

<p>aIncludes <i>Enterobius</i> infections</p><p>Helminth infection prevalence by age, helminth, and infection intensity.</p

Cluster-level STH prevalence by cluster-level hygienic latrine coverage.

<p>Panel A shows the cluster-level prevalence of <i>Ascaris</i>, Panel B shows the prevalence of hookworm, and Panel C shows the prevalence of <i>Trichuris</i> by the proportion of respondents with hygienic latrines in each cluster.</p

Map of soil-transmitted helminth prevalence in Bangladesh.

<p>We mapped STH prevalence in each study cluster for which valid GPS coordinates were available (n = 99). Panel A shows the cluster-level prevalence of any STH infection, Panel B shows the prevalence of <i>Ascaris lumbricoides</i>, Panel C shows the prevalence of hookworm, and Panel D shows the prevalence of <i>Trichuris trichiura</i>.</p

Prevalence ratios for deworming, hygienic latrine access, and finished floors.

<p>^aThe number of observations was slightly lower for adjusted prevalence ratios because some observations of potential confounders had missing values.</p><p>^bPRs estimated using modified Poisson regression and adjusted for age, sex, sub-district, household wealth, cluster-level wealth, and mother’s education level.</p><p>Prevalence ratios for deworming, hygienic latrine access, and finished floors.</p