Baseline patterns of infection in regions of Benin, Malawi and India seeking to interrupt transmission of soil transmitted helminths (STH) in the DeWorm3 trial

Adolescents' Perspective Regarding a Community-Wide Mass Drug Administration Program for Soil-Transmitted Helminths in India

This study was undertaken to understand the perspective of adolescents in endemic communities of India regarding soil-transmitted helminth (STH) infections and community-wide mass drug administration (cMDA). A multicountry community-based cluster-randomized trial, the Deworm3 trial, tested the feasibility of interrupting STH transmission with cMDA, where all individuals aged 1-99 are treated empirically with albendazole. Using a guideline based on the Consolidated Framework for Implementation Research, eight focus group discussions were conducted among 57 adolescents from the trial site in India and analyzed on ATLAS.ti 8.0 software using an a priori thematic codebook. Adolescents believed that adults could be a source of STH infection because they were not routinely dewormed like the children through the national deworming program. Perceived benefits of cMDA for all were better health and increased work efficiency. Perceived barriers to adults' participation in cMDA was their mistrust about the program, fear of side effects, perceived low risk of infection, and absence during drug distribution. To encourage adult participation in cMDAs, adolescents suggested community outreach activities, engaging village influencers and health workers, and tailoring drug distribution to when adults would be available. Adolescents were confident in their ability to be change agents within their households for treatment compliance. Adolescents provided insights into potential barriers and solutions to improve adult participation in cMDA, identified best practices of cMDA delivery, and suggested that they have unique roles as change agents to increase their household participation in cMDA.

Representativeness of a mobile phone-based coverage evaluation survey following mass drug administration for soil-transmitted helminths: a comparison of participation between two cross-sectional surveys

OBJECTIVES

With increasing mobile phone subscriptions, phone-based surveys are gaining popularity with public health programmes. Despite advantages, systematic exclusion of participants may limit representativeness. Similar to control programmes for neglected tropical diseases (NTDs), the DeWorm3 trial of biannual community-wide mass drug administration (MDA) for elimination of soil-transmitted helminth infection used in-person coverage evaluation surveys to measure the proportion of the at-risk population treated during MDA. Due to lockdown during the COVID-19 pandemic, a phone-based coverage evaluation survey was necessary, providing an opportunity for the current study to compare representativeness and implementation (including non-response) of these two survey modes.

DESIGN

Comparison of two cross-sectional surveys.

SETTING

The DeWorm3 trial site in Tamil Nadu, India, includes Timiri, a rural subsite, and Jawadhu Hills, a hilly, hard-to-reach subsite inhabited predominantly by a tribal population.

PARTICIPANTS

In the phone-based and in-person coverage evaluation surveys, all individuals residing in 2000 randomly selected households (50 in each of the 40 trial clusters) were eligible to participate. Here, we characterise household participation.

RESULTS

Of 2000 households, 1780 (89.0%) participated during the in-person survey. Of 2000 households selected for the phone survey, 346 (17.3%) could not be contacted as they had not provided a telephone number during the census and 1144 (57.2%) participated. Smaller households, households with lower socioeconomic status and those with older, women or less educated household-heads were under-represented in the phone-based survey compared with censused households. Regression analysis revealed non-response in the phone-based survey was higher among households from the poorest socioeconomic quintile (prevalence ratio (PR) 2.3, 95% CI 2.0 to 2.7) and lower when heads of households had completed secondary school or higher education (PR 0.7, 95% CI 0.6 to 0.8).

CONCLUSIONS

Our findings suggest phone-based surveys under-represent households likely to be at higher risk of NTDs and in-person surveys are more appropriate for measuring MDA coverage within programmatic settings.

TRIAL REGISTRATION NUMBER

NCT03014167.

Impact of adverse events during community-wide mass drug administration for soil-transmitted helminths on subsequent participation-a Theory of Planned Behaviour analysis

BACKGROUND

Experiencing adverse events (AEs) during mass drug administration (MDA) could affect participation in future MDAs. This study aims to understand the potential influence of AEs during a community-wide MDA (cMDA) trial for soil-transmitted helminths (STH) in India on intention to participate in future cMDAs.

METHODS

This study was conducted using a multi-method quantitative and qualitative approach among 74 participants who experienced an AE during STH cMDA and the 12 participants who subsequently refused cMDA treatment of the ongoing DeWorm3 trial. Path analysis and thematic analysis guided by the Theory of Planned Behaviour, was used.

PRINCIPAL FINDINGS

Among 74 individuals who reported an AE, 12% refused treatment in the cMDA immediately subsequent to their AE and 4% refused in all subsequent cMDAs. Of these 74 individuals, 59 (80%) completed a survey and eight participated in in-depth interviews. A positive attitude towards deworming and perceived ability to participate in cMDA (perceived behavioural control) were significant predictors of intention to participate in cMDA (p<0.05). A positive attitude towards cMDA was associated with caste (χ2 = 3.83, P = 0.05), particularly among the scheduled caste/scheduled tribe (SC/ST) (62%). Perceived behavioural control in cMDA participation was associated with occupation (χ2 = 5.02, P<0.05), with higher perceived control among those engaged in skilled occupations (78%). Intention to participate in subsequent cMDAs was associated with caste and family type (χ2 = 3.83, P = 0.05 and χ2 = 7.50, P<0.05 respectively) and was higher among SC/ST (62%) and those with extended families (67%). In-depth interviews demonstrated that perceived severe AEs may lead to treatment refusal in future, particularly if children were affected.

CONCLUSIONS

Intention to participate in future STH cMDAs was associated with caste (SC/ST) and family type (extended families). Therefore, community mobilization messages about potential AEs and their management may need to intentionally target non-SC/ST households, nuclear families, and those engaged in unskilled occupations to increase cMDA participation given the possibility of AEs occurring.

TRIAL REGISTRATION

NCT03014167, ClinicalTrials.gov.

Multiple overlapping risk factors for childhood wheeze among children in Benin

BACKGROUND

The African continent is currently facing an epidemiological transition characterized by a shift from communicable to non-communicable diseases. Prominent amongst the latter are allergies and asthma. In that context, wheeze has multiple potential contributory factors that could include some of the endemic helminth infections, as well as environmental exposures, such as household air pollution. We sought to determine the relative importance of these risk factors among children in Benin.

METHODS

We included 964 children aged 6-14 years living in the commune of Comé, south-west Benin. All children were participants in the longitudinal monitoring cohort of the DeWorm3 trial designed to evaluate multiple rounds of community mass treatment with albendazole for interruption of the transmission of soil transmitted helminths (STH). We administered a standard ISAAC questionnaire to determine the presence of wheeze. In addition, we assessed exposure to household air pollution and to other potential allergy-inducing factors, dietary intake and anthropometry. Using STH infection status assessed at the pretreatment baseline timepoint, we used multivariate statistical modelling, controlling for covariates, to investigate associations between wheeze and the different factors measured.

RESULTS

The prevalence of wheezing history was 5.2%, of current wheezing was 4.6% and of severe wheezing was 3.1%, while STH infections were found in 5.6% of children. These profiles did not vary as a function of either age or gender. Infection with Ascaris lumbricoides, but not hookworm species, was significantly associated with both current wheeze (adjusted Odds Ratio (aOR) = 4.3; 95% CI [1.5-12.0]) and severe wheeze (aOR = 9.2; 95% CI [3.1-27.8]). Significant positive associations with current wheeze, independent of each other and of STH infection status, were also found for (i) use of open cookstoves (aOR = 3.9; 95% CI [1.3-11.5]), (ii) use of palm cakes for fire lighting (aOR = 3.4; 95% CI [1.1-9.9]), (iii) contact with domestic animals and/or rodents (aOR = 2.5; 95% CI [1.1-6.0]), (iv) being overweight (aOR = 9.7; 95% CI [1.7-55.9]). Use of open cookstoves and being overweight were also independent risk factors for severe wheeze (aOR = 3.9; 95% CI [1.1-13.7]) and aOR = 10.3; 95% CI [1.8-60.0], respectively).

CONCLUSIONS

Children infected with A. lumbricoides appear to be at elevated risk of wheeze. Deworming may be an important intervention to reduce these symptoms. Improving cooking methods to reduce household air pollution, modifying dietary habits to avoid overweight, and keeping animals out of the house are all additional measures that could also contribute to reducing childrens' risk of wheeze. Policymakers in LMIC should consider tailoring public health measures to reflect the importance of these different risk factors.

Policy stakeholder perspectives on barriers and facilitators to launching a community-wide mass drug administration program for soil-transmitted helminths

BACKGROUND

Recent evidence suggests that soil-transmitted helminth (STH) transmission interruption may be feasible through community-wide mass drug administration (cMDA) that deworms community members of all ages. A change from school-based deworming to cMDA will require reconfiguring of STH programs in endemic countries. We conducted formative qualitative research in Benin, India, and Malawi to identify barriers and facilitators to successfully launching a cMDA program from the policy-stakeholder perspective.

METHODS

We conducted 40 key informant interviews with policy stakeholders identified as critical change agents at national, state/district, and sub-district levels. Participants included World Health Organization country office staff, implementing partners, and national and sub-national government officials. We used the Consolidated Framework for Implementation Research to guide data collection, coding, and analysis. Heat maps were used to organize coded data and differentiate perceived facilitators and barriers to launching cMDA by stakeholder.

RESULTS

Key facilitators to launching a cMDA program included availability of high-quality, tailored sensitization materials, and human and material resources that could be leveraged from previous MDA campaigns. Key barriers included the potential to overburden existing health workers, uncertainty of external funding to sustain a cMDA program, and concerns about weak intragovernmental coordination to implement cMDA. Cross-cutting themes included the need for rigorous trial evidence on STH transmission interruption to gain confidence in cMDA, and implementation evidence to effectively operationalize cMDA. Importantly, if policy stakeholders anticipate a cMDA program cannot be sustained due to cost and human resource barriers in the long term they may be less likely to support the launch of a program in the short term.

CONCLUSIONS

Overall, policy stakeholders were optimistic about implementing cMDA primarily because they believe that the tools necessary to successfully implement cMDA are already available. Policy stakeholders in this study were cautiously optimistic about launching cMDA to achieve STH transmission interruption and believe that it is feasible to implement. However, launching cMDA as an alternative policy to school-based deworming will require addressing key resource and evidence barriers. Trial registration This study was registered in the U.S. National Library of Medicine Clinical Trials registry (NCT03014167).

Impact of the COVID-19 National Lockdown on a Rural and Tribal Population of Tamil Nadu, Southern India: A Mixed-Methods Survey

We assessed the impact of the national lockdown on a rural and tribal population in Tamil Nadu, southern India. A mixed-methods approach with a pilot-tested, semi-structured questionnaire and focus group discussions were used. The impact of the lockdown on health, finances, and livelihood was studied using descriptive statistics. Multivariable logistic regression was carried out to identify factors associated with households that borrowed loans or sold assets during the lockdown, and unemployment during the lockdown. Of the 607 rural and tribal households surveyed, households from comparatively higher socioeconomic quintiles (adjusted odds ratio [aOR], 1.84; 95% CI, 1.01-3.34), with no financial savings (aOR, 2.91; 95% CI, 1.17-7.22), and with larger families (aOR, 1.76; 95% CI, 1.22-2.53), took loans or sold assets during the lockdown. Previously employed individuals from rural households (aOR, 5.07; 95% CI, 3.30-7.78), lower socioeconomic households (aOR, 3.08; 95% CI, 1.74, 5.45), and households with no savings (aOR, 1.78; 95% CI, 1.30-2.44) became predominantly unemployed during the lockdown. Existing government schemes for the elderly, differently abled, and widows were shown to be accessible to 89% of the individuals requiring these schemes in our survey. During the focus group discussions, the limited reach of online classes for schoolchildren was noted and attributed to the lack of smartphones and poor Internet connectivity. Although the sudden, unannounced national lockdown was imposed to flatten the COVID-19 curve, aspects related to livelihood and financial security were affected for both the rural and tribal populations.

Community Drug Distributor Knowledge, Attitudes, and Motivation Surrounding Mass Drug Administration for Soil-Transmitted Helminths in India

Background: DeWorm3 is an ongoing multi-country community-based cluster-randomized trial assessing the feasibility of interrupting transmission of soil-transmitted helminths (STH) with community-wide mass drug administration (cMDA). In Tamil Nadu, India, community drug distributors (CDDs) worked with DeWorm3 field staff to counsel community members and deliver door-to-door deworming treatment. As CDDs were likely to influence successful delivery of cMDA, we describe drivers of CDDs' knowledge, attitudes, and motivation toward delivery of cMDA.

Methods: In this convergent mixed-methods study, a questionnaire on STH and cMDA was administered to 104 CDDs and 17 focus group discussions (FGDs) were conducted. Key outcomes in the quantitative and qualitative analyses included CDDs' knowledge about STH and cMDA and attitudes toward cMDA for STH. Univariate and multivariable logistic regression analyses were performed to determine the strength of associations between independent and outcome variables. The FGDs were analyzed using a priori thematic coding.

Results: CDDs who completed at least secondary school education [adjusted odds ratio (aOR): 2.71, 95% CI: 1.16–6.33] and had prior experience in health programs (aOR: 2.72, 95% CI: 1.15–6.44) were more knowledgeable about STH and cMDA. CDDs belonging to the scheduled castes and scheduled tribes (aOR: 2.37, 95% CI: 1.04–5.39), and to households engaged in a skilled occupation (aOR: 2.77, 95% CI: 1.21–6.34) had a more positive attitude toward cMDA for STH. The FGDs showed that while there were myths and misconceptions about STH, many CDDs believed that the adult population in their communities were infected with STH, and that a door-to-door drug delivery strategy would be optimal to reach adults.

Conclusions: Educational and socioeconomic backgrounds and experience in health programs should be considered while designing CDD trainings. Along with cMDA delivery for STH, as CDD do share community myths and misconceptions around STH, they should be proactively addressed during the CDD training to strengthen competency in counseling.

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

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 to assess the feasibility of using community-based MDA with albendazole to interrupt the transmission of STH, through a series of cluster-randomized 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 Comé, the study site of the DeWorm3 project 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 March and 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 Comé, Benin using a stratified random sampling procedure. A standardized 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 and above). Multilevel mixed-effects models were used to assess associations between these factors and STH infection.

Results

The overall 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), and having 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^rd 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 secondary 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).

Conclusion

Hookworm spp. are the most prevalent STH in Comé, with a persistent 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, particularly for hookworm.

Trial registration

ClinicalTrials.gov NCT03014167.

Despite several years of deworming campaigns targeting school-aged children, soil-transmitted helminths (STH) remains a public health problem in most developing countries, including Benin. The burden is mostly on children and pregnant women, but also on the whole society. Soil-transmitted helminths are responsible for malnutrition, anemia, low birth weight, cognitive impairment, decrease of school performance, and subsequently economic loss. The current strategy of the Benin National Neglected Tropical Diseases (NTD) Program is to achieve STH control through mass drug administration campaigns targeting school-aged children (SAC). The baseline data of Deworm3 study, implemented in Comé, southern Benin, as part of a multicountry (Benin, Malawi and India) STH elimination trial, shows that previous school deworming campaigns decreased STH prevalence; however there is a persistent reservoir of STH infection in adults and pre-school aged children that should be targeted for a better impact. In order to eliminate STH as a public health problem, Benin National NTD Program would need to increase its target population, from the SAC to the whole community. The future results of Deworm3 trial would demonstrate whether the STH elimination goal STH using community wide mass drug administration would be achievable.

Effect of mass deworming with antihelminthics for soil-transmitted helminths during pregnancy

BACKGROUND

Helminthiasis is an infestation of the human body with parasitic worms. It is estimated to affect 44 million pregnancies, globally, each year. Intestinal helminthiasis (hookworm infestation) is associated with blood loss and decreased supply of nutrients for erythropoiesis, resulting in iron-deficiency anaemia. Over 50% of the pregnant women in low- and middle-income countries (LMIC) suffer from iron-deficiency anaemia. Though iron-deficiency anaemia is multifactorial, hookworm infestation is a major contributory cause in women of reproductive age in endemic areas. Antihelminthics are highly efficacious, but evidence of their beneficial effect and safety when given during pregnancy has not been established. This is an update of a Cochrane Review last published in 2015.

OBJECTIVES

To determine the effects of mass deworming with antihelminthics for soil-transmitted helminths (STH) during the second or third trimester of pregnancy on maternal and pregnancy outcomes.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP) (8 March 2021) and reference lists of retrieved studies.

SELECTION CRITERIA

We included all prospective randomised controlled trials evaluating the effect of administration of antihelminthics versus placebo or no treatment during the second or third trimester of pregnancy; both individual-randomised and cluster-randomised trials were eligible. We excluded quasi-randomised trials and studies that were only available as abstracts with insufficient information.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data, checked accuracy and assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included a total of six trials (24 reports) that randomised 7873 pregnant women. All of the included trials were conducted in antenatal clinics within hospitals in LMICs (Uganda, Nigeria, Peru, India, Sierra Leone and Tanzania). Among primary outcomes, five trials reported maternal anaemia, one trial reported preterm birth and three trials reported perinatal mortality. Among secondary outcomes, included trials reported maternal worm prevalence, low birthweight (LBW) and birthweight. None of the included studies reported maternal anthropometric measures or infant survival at six months. Overall, we judged the included trials to be generally at low risk of bias for most domains, while the certainty of evidence ranged from low to moderate. Analysis suggests that administration of a single dose of antihelminthics in the second trimester of pregnancy may reduce maternal anaemia by 15% (average risk ratio (RR) 0.85, 95% confidence interval (CI) 0.72 to 1.00; I²= 86%; 5 trials, 5745 participants; low-certainty evidence). We are uncertain of the effect of antihelminthics during pregnancy on preterm birth (RR 0.84, 95% CI 0.38 to 1.86; 1 trial, 1042 participants; low-certainty evidence) or perinatal mortality (RR 1.01, 95% CI 0.67 to 1.52; 3 trials, 3356 participants; low-certainty evidence). We are uncertain of the effect of antihelminthics during pregnancy on hookworm (average RR 0.31, 95% CI 0.05 to 1.93; Tau² = 1.76, I² = 99%; 2 trials, 2488 participants; low-certainty evidence). Among other secondary outcomes, findings suggest that administration of antihelminthics during pregnancy may reduce the prevalence of trichuris (average RR 0.68, 95% CI 0.48 to 0.98; I²=75%; 2 trials, 2488 participants; low-certainty evidence) and ascaris (RR 0.24, 95% CI 0.19 to 0.29; I²= 0%; 2 trials, 2488 participants; moderate-certainty evidence). Antihelminthics during pregnancy probably make little or no difference to LBW (RR 0.89, 95% CI 0.69 to 1.16; 3 trials, 2960 participants; moderate-certainty evidence) and birthweight (mean difference 0.00 kg, 95% CI -0.03 kg to 0.04 kg; 3 trials, 2960 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

The evidence suggests that administration of a single dose of antihelminthics in the second trimester of pregnancy may reduce maternal anaemia and worm prevalence when used in settings with high prevalence of maternal helminthiasis. Further data is needed to establish the benefit of antihelminthic treatment on other maternal and pregnancy outcomes. Future research should focus on evaluating the effect of these antihelminthics among various subgroups in order to assess whether the effect varies. Future studies could also assess the effectiveness of co-interventions and health education along with antihelminthics for maternal and pregnancy outcomes.

Epidemiology of soil transmitted helminths and risk analysis of hookworm infections in the community: Results from the DeWorm3 Trial in southern India

Since 2015, India has coordinated the largest school-based deworming program globally, targeting soil-transmitted helminths (STH) in ~250 million children aged 1 to 19 years twice yearly. Despite substantial progress in reduction of morbidity associated with STH, reinfection rates in endemic communities remain high. We conducted a community based parasitological survey in Tamil Nadu as part of the DeWorm3 Project—a cluster-randomised trial evaluating the feasibility of interrupting STH transmission at three geographically distinct sites in Africa and Asia—allowing the estimation of STH prevalence and analysis of associated factors. In India, following a comprehensive census, enumerating 140,932 individuals in 36,536 households along with geospatial mapping of households, an age-stratified sample of individuals was recruited into a longitudinal monitoring cohort (December 2017-February 2018) to be followed for five years. At enrolment, a total of 6089 consenting individuals across 40 study clusters provided a single adequate stool sample for analysis using the Kato-Katz method, as well as answering a questionnaire covering individual and household level factors. The unweighted STH prevalence was 17.0% (95% confidence interval [95%CI]: 16.0–17.9%), increasing to 21.4% when weighted by age and cluster size. Hookworm was the predominant species, with a weighted infection prevalence of 21.0%, the majority of which (92.9%) were light intensity infections. Factors associated with hookworm infection were modelled using mixed-effects multilevel logistic regression for presence of infection and mixed-effects negative binomial regression for intensity. The prevalence of both Ascaris lumbricoides and Trichuris trichiura infections were rare (<1%) and risk factors were therefore not assessed. Increasing age (multivariable odds ratio [mOR] 21.4, 95%CI: 12.3–37.2, p<0.001 for adult age-groups versus pre-school children) and higher vegetation were associated with an increased odds of hookworm infection, whereas recent deworming (mOR 0.3, 95%CI: 0.2–0.5, p<0.001) and belonging to households with higher socioeconomic status (mOR 0.3, 95%CI: 0.2–0.5, p<0.001) and higher education level of the household head (mOR 0.4, 95%CI: 0.3–0.6, p<0.001) were associated with lower odds of hookworm infection in the multilevel model. The same factors were associated with intensity of infection, with the use of improved sanitation facilities also correlated to lower infection intensities (multivariable infection intensity ratio [mIIR] 0.6, 95%CI: 0.4–0.9, p<0.016). Our findings suggest that a community-based approach is required to address the high hookworm burden in adults in this setting. Socioeconomic, education and sanitation improvements alongside mass drug administration would likely accelerate the drive to elimination in these communities.

Trial Registration:NCT03014167.

Approximately 1 in 5 people in India are infected with soil transmitted helminths (STH), leading to anaemia and malnutrition. To tackle this large burden of infection, the government of India launched one of the world’s largest school-based deworming programs in 2015 aiming to deworm all pre-school and school-aged children between 1 to 19 years of age twice yearly on the National Deworming Days. Deworming programs, including those in India, are focused on pre-school aged children, school aged children and women of reproductive age group. However, prevailing environmental and socioeconomic conditions, including poor sanitation, can contribute to high rates of reinfection from untreated adults and children. The DeWorm3 Project is a cluster-randomised trial evaluating the feasibility of interrupting STH transmission with community wide deworming of all individuals aged one to 99 years of age or older. As part of the study, we conducted a parasitological survey in the Deworm3 trial site in rural Tamil Nadu. Here we present the factors associated with STH infection and burden in these communities.

Forecasting the effectiveness of the DeWorm3 trial in interrupting the transmission of soil-transmitted helminths in three study sites in Benin, India and Malawi

Background

The DeWorm3 project is an ongoing cluster-randomised trial assessing the feasibility of interrupting the transmission of soil-transmitted helminths (STH) through mass drug administration (MDA) using study sites in India, Malawi and Benin. In this article, we describe an approach which uses a combination of statistical and mathematical methods to forecast the outcome of the trial with respect to its stated goal of reducing the prevalence of infection to below 2%.

Methods

Our approach is first to define the local patterns of transmission within each study site, which is achieved by statistical inference of key epidemiological parameters using the baseline epidemiological measures of age-related prevalence and intensity of STH infection which have been collected by the DeWorm3 trials team. We use these inferred parameters to calibrate an individual-based stochastic simulation of the trial at the cluster and study site level, which is subsequently run to forecast the future prevalence of STH infections. The simulator takes into account both the uncertainties in parameter estimation and the variability inherent in epidemiological and demographic processes in the simulator. We interpret the forecast results from our simulation with reference to the stated goal of the DeWorm3 trial, to achieve a target of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\le 2\%$$\end{document}≤2% prevalence at a point 24 months post-cessation of MDA.

Results

Simulated output predicts that the two arms will be distinguishable from each other in all three country sites at the study end point. In India and Malawi, measured prevalence in the intervention arm is below the threshold with a high probability (90% and 95%, respectively), but in Benin the heterogeneity between clusters prevents the arm prevalence from being reduced below the threshold value. At the level of individual study arms within each site, heterogeneity among clusters leads to a very low probability of achieving complete elimination in an intervention arm, yielding a post-study scenario with widespread elimination but a few ‘hot spot’ areas of persisting STH transmission.

Conclusions

Our results suggest that geographical heterogeneities in transmission intensity and worm aggregation have a large impact on the effect of MDA. It is important to accurately assess cluster-level, or even smaller scale, heterogeneities in factors which influence transmission and aggregation for a clearer perspective on projecting the outcomes of MDA control of STH and other neglected tropical diseases.