Factors associated with soil-transmitted helminths infection in Benin: Findings from the DeWorm3 study

Abstract

Background Despite several years of school-based MDA implementation, STH infections remain an important public health problem in Benin, with a country-wide prevalence of 20% in 2015. The DeWorm3 study is designed toassess the feasibility of using community-based MDA with albendazole to interrupt the transmission of STH, through a series of cluster-random ized trials in Benin, India and Malawi. We used the pre-treatment baseline survey data to describe and analyze the factors associated with STH infection in Come´, the study site of the DeWorm3project in Benin. These data will improve understanding of the challenges that need to be addressed in order to eliminate STH as a public health problem in Benin. Methods Between Marchand April 2018, the prevalence of STH (hookworm spp., Ascaris and Trichuris trichiura) was assessed by Kato-Katz in stool samples collected from 6,153 residents in the community of Come´, Benin using a stratified random sampling procedure. A standard ized survey questionnaire was used to collect information from individual households concerning factors potentially associated with the presence and intensity of STH infections in pre-school (PSAC, aged 1–4), school-aged children (SAC, aged 5–14) and adults (aged 15 andabove). Multilevel mixed-effects models were used to assess associations between these factors and STH infection. Results Theoverall prevalence of STH infection was 5.3%; 3.2% hookworm spp., 2.1% Ascaris lumbricoides and 0.1% Trichuris. Hookworm spp. were more prevalent in adults than in SAC (4.4% versus 2.0%, respectively; p = 0.0001) and PSAC (4.4% versus 1.0%, respectively; p<0.0001), whilst Ascaris lumbricoides was more prevalent in SAC than in adults (3.0% versus 1.7%, respectively; p = 0.004). Being PSAC (adjusted Odds Ratio (aOR) = 0.2, p< 0.001; adjusted Infection Intensity Ratio (aIIR) = 0.1, p<0.001) or SAC (aOR = 0.5, p = 0.008; aIIR = 0.3, p = 0.01), being a female (aOR = 0.6, p = 0.004; aIIR = 0.3, p = 0.001), andhaving received deworming treatment the previous year (aOR = 0.4, p< 0.002; aIIR = 0.2, p<0.001) were associated with a lower prevalence and intensity of hookworm infection. Lower income (lowest quintile: aOR = 5.0, p<0.001, 2 nd quintile aOR = 3.6, p = 0.001 and 3 quintile aOR = 2.5, p = 0.02), being a farmer (aOR = 1.8, p = 0.02), medium population density (aOR = 2.6, p =0.01), and open defecation (aOR = 0.5, p = 0.04) were associated with a higher prevalence of hookworm infection. Lower education—no education, primary or sec ondary school- (aIIR = 40.1, p = 0.01; aIIR = 30.9, p = 0.02; aIIR = 19.3, p = 0.04, respectively), farming (aIIR = 3.9, p = 0.002), natural flooring (aIIR = 0.2, p = 0.06), peri-urban settings (aIIR = 6.2, 95%CI 1.82–20.90, p = 0.003), and unimproved water source more than 30 minutes from the household (aIIR = 13.5, p = 0.02) were associated with a higher intensity of hookworm infection. Improved and unshared toilet was associated with lower intensity of hookworm infections (aIIR = 0.2, p = 0.01). SAC had a higher odds of Ascaris lumbricoides infection than adults (aOR = 2.0, p = 0.01) and females had a lower odds of infection (aOR = 0.5, p = 0.02). rd Conclusion Hookwormspp.arethe mostprevalent STH in Come´,with apersistent reservoir in adults that is not addressed by current control measures based on school MDA. Expanding MDA to target adults and PSAC is necessary to substantially impact population prevalence, par ticularly for hookworm.