Water,Sanitation, Hygiene,and Soil-Transmitted Helminth Infection: A Systematic Review and Meta-Analysis

Background

Preventive chemotherapy represents a powerful but short-term control strategy for soil-transmitted helminthiasis. Since humans are often re-infected rapidly, long-term solutions require improvements in water, sanitation, and hygiene (WASH). The purpose of this study was to quantitatively summarize the relationship between WASH access or practices and soil-transmitted helminth (STH) infection.

Methods and Findings

We conducted a systematic review and meta-analysis to examine the associations of improved WASH on infection with STH (Ascaris lumbricoides, Trichuris trichiura, hookworm [Ancylostoma duodenale and Necator americanus], and Strongyloides stercoralis). PubMed, Embase, Web of Science, and LILACS were searched from inception to October 28, 2013 with no language restrictions. Studies were eligible for inclusion if they provided an estimate for the effect of WASH access or practices on STH infection. We assessed the quality of published studies with the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach. A total of 94 studies met our eligibility criteria; five were randomized controlled trials, whilst most others were cross-sectional studies. We used random-effects meta-analyses and analyzed only adjusted estimates to help account for heterogeneity and potential confounding respectively.Use of treated water was associated with lower odds of STH infection (odds ratio [OR] 0.46, 95% CI 0.36–0.60). Piped water access was associated with lower odds of A. lumbricoides (OR 0.40, 95% CI 0.39–0.41) and T. trichiura infection (OR 0.57, 95% CI 0.45–0.72), but not any STH infection (OR 0.93, 95% CI 0.28–3.11). Access to sanitation was associated with decreased likelihood of infection with any STH (OR 0.66, 95% CI 0.57–0.76), T. trichiura (OR 0.61, 95% CI 0.50–0.74), and A. lumbricoides (OR 0.62, 95% CI 0.44–0.88), but not with hookworm infection (OR 0.80, 95% CI 0.61–1.06). Wearing shoes was associated with reduced odds of hookworm infection (OR 0.29, 95% CI 0.18–0.47) and infection with any STH (OR 0.30, 95% CI 0.11–0.83). Handwashing, both before eating (OR 0.38, 95% CI 0.26–0.55) and after defecating (OR 0.45, 95% CI 0.35–0.58), was associated with lower odds of A. lumbricoides infection. Soap use or availability was significantly associated with lower infection with any STH (OR 0.53, 95% CI 0.29–0.98), as was handwashing after defecation (OR 0.47, 95% CI 0.24–0.90).Observational evidence constituted the majority of included literature, which limits any attempt to make causal inferences. Due to underlying heterogeneity across observational studies, the meta-analysis results reflect an average of many potentially distinct effects, not an average of one specific exposure-outcome relationship.

Conclusions

WASH access and practices are generally associated with reduced odds of STH infection. Pooled estimates from all meta-analyses, except for two, indicated at least a 33% reduction in odds of infection associated with individual WASH practices or access. Although most WASH interventions for STH have focused on sanitation, access to water and hygiene also appear to significantly reduce odds of infection. Overall quality of evidence was low due to the preponderance of observational studies, though recent randomized controlled trials have further underscored the benefit of handwashing interventions. Limited use of the Joint Monitoring Program''s standardized water and sanitation definitions in the literature restricted efforts to generalize across studies. While further research is warranted to determine the magnitude of benefit from WASH interventions for STH control, these results call for multi-sectoral, integrated intervention packages that are tailored to social-ecological contexts. Please see later in the article for the Editors'' Summary     

Exploring the Relationship between Access to Water,Sanitation and Hygiene and Soil-Transmitted Helminth Infection: A Demonstration of Two Recursive Partitioning Tools

Background

Soil-transmitted helminths (STH) – a class of parasites that affect billions of people – can be mitigated using mass drug administration, though reinfection following treatment occurs within a few months. Improvements to water, sanitation and hygiene (WASH) likely provide sustained benefit, but few rigorous studies have evaluated the specific WASH components most influential in reducing infection. There is a need for alternative analytic approaches to help identify, characterize and further refine the WASH components that are most important to STH reinfection. Traditional epidemiological approaches are not well-suited for assessing the complex and highly correlated relationships commonly seen in WASH.

Methodology

We introduce two recursive partitioning approaches: classification and regression trees (C&RT) and conditional inference trees (CIT), which can be used to identify complex interactions between WASH indicators and identify sub-populations that may be susceptible to STH reinfection. We illustrate the advantages and disadvantages of these approaches utilizing school- and household-level WASH indicators gathered as part of a school-based randomized control trial in Kenya that measured STH reinfection of pupils 10 months following deworming treatment.

Principal Findings

C&RT and CIT analyses resulted in strikingly different decision trees. C&RT may be the preferred approach if interest lies in using WASH indicators to classify individuals or communities as STH infected or uninfected, whereas CIT is most appropriate for identifying WASH indicators that may be causally associated with STH infection. Both tools are well-suited for identifying complex interactions among WASH indicators.

Conclusions/Significance

C&RT and CIT are two analytic approaches that may offer valuable insight regarding the identification, selection and refinement of WASH indicators and their interactions with regards to STH control programs; however, they represent solutions to two distinct research questions and careful consideration should be made before deciding which approach is most appropriate.     

School Water,Sanitation, and Hygiene,Soil-Transmitted Helminths,and Schistosomes: National Mapping in Ethiopia

BackgroundIt is thought that improving water, sanitation, and hygiene (WASH) might reduce the transmission of schistosomes and soil-transmitted helminths, owing to their life cycles. However, few large-scale studies have yet assessed the real extent of associations between WASH and these parasites.Conclusions/SignificanceImproving school WASH may reduce transmission of these parasites. However, different forms of WASH appear to have different effects on infection with the various parasites, with our analysis finding the strongest associations between water and S. mansoni, sanitation and A. lumbricoides, and hygiene and hookworm.     

Effect of Sanitation on Soil-Transmitted Helminth Infection: Systematic Review and Meta-Analysis

Background

In countries of high endemicity of the soil-transmitted helminth parasites Ascaris lumbricoides, Trichuris trichiura, and hookworm, preventive chemotherapy (i.e., repeated administration of anthelmintic drugs to at-risk populations) is the main strategy to control morbidity. However, rapid reinfection of humans occurs after successful deworming, and therefore effective preventive measures are required to achieve public health goals with optimal efficiency and sustainability.

Methods and Findings

We conducted a systematic review and meta-analysis to assess the effect of sanitation (i.e., access and use of facilities for the safe disposal of human urine and feces) on infection with soil-transmitted helminths. PubMed, Embase, ISI Web of Science, and the World Health Organization Library Database were searched without language restrictions and year of publication (search performed until December 31, 2010). Bibliographies of identified articles were hand-searched. All types of studies reporting data on sanitation availability (i.e., having access at own household or living in close proximity to sanitation facility), or usage, and soil-transmitted helminth infections at the individual level were considered. Reported odds ratios (ORs) of the protective effect of sanitation on soil-transmitted helminth infections were extracted from the papers or calculated from reported numbers. The quality of published studies was assessed with a panel of criteria developed by the authors. Random effects meta-analyses were used to account for observed heterogeneity. Thirty-six publications, consisting of 39 datasets, met our inclusion criteria. Availability of sanitation facilities was associated with significant protection against infection with soil-transmitted helminths (OR  =  0.46 to 0.58). Regarding the use of sanitation, ORs of 0.54 (95% confidence interval [CI] 0.28–1.02), 0.63 (95% CI 0.37–1.05), and 0.78 (95% CI 0.60–1.00) were determined for T. trichiura, hookworm, and A. lumbricoides, respectively. The overall ORs, combining sanitation availability and use, were 0.51 (95% CI 0.44–0.61) for the three soil-transmitted helminths combined, 0.54 (95% CI 0.43–0.69) for A. lumbricoides, 0.58 (95% CI 0.45–0.75) for T. trichiura, and 0.60 (95% CI 0.48–0.75) for hookworm.

Conclusions

Despite a number of limitations (e.g., most studies used a cross-sectional design and were of low quality, with potential biases and considerable heterogeneity), our results reveal that sanitation is associated with a reduced risk of transmission of helminthiases to humans. Access to improved sanitation should be prioritized alongside preventive chemotherapy and health education to achieve a durable reduction of the burden of helminthiases. Please see later in the article for the Editors'' Summary     

A Cross-Sectional Study of Water,Sanitation, and Hygiene-Related Risk Factors for Soil-Transmitted Helminth Infection in Urban School- and Preschool-Aged Children in Kibera,Nairobi

Soil-transmitted helminth (STH) infections affect persons living in areas with poor water, sanitation, and hygiene (WASH). Preschool-aged children (PSAC) and school-aged children (SAC) are disproportionately affected by STH infections. We aimed to identify WASH factors associated with STH infection among PSAC and SAC in Kibera, Kenya. In 2012, households containing a PSAC or SAC were randomly selected from those enrolled in the International Emerging Infections Program, a population-based surveillance system. We administered a household questionnaire, conducted environmental assessments for WASH, and tested three stools from each child for STH eggs using the Kato-Katz method. WASH factors were evaluated for associations with STH infection using univariable and multivariable Poisson regression. Any-STH prevalence was 40.8% among 201 PSAC and 40.0% among 475 SAC enrolled. Using the Joint Monitoring Programme water and sanitation classifications, 1.5% of households reported piped water on premises versus 98.5% another improved water source; 1.3% reported improved sanitation facilities, while 81.7% used shared sanitation facilities, 13.9% had unimproved facilities, and 3.1% reported no facilities (open defecation). On univariable analysis, STH infection was significantly associated with a household toilet located off-premises (prevalence ratio (PR) = 1.33; p = 0.047), while always treating water (PR = 0.81; p = 0.04), covering drinking water containers (PR = 0.75; p = 0.02), using clean towels during hand drying (PR = 0.58; p<0.01), having finished household floor material (PR = 0.76; p<0.01), having electricity (PR = 0.70; p<0.01), and increasing household elevation in 10-meter increments (PR = 0.89; p<0.01) were protective against STH infection. On multivariable analysis, usually versus always treating water was associated with increased STH prevalence (adjusted prevalence ratio (aPR) = 1.52; p<0.01), while having finished household floor material (aPR = 0.76; p = 0.03), reported child deworming in the last year (aPR = 0.76; p<0.01), and 10-meter household elevation increases (aPR = 0.89; p<0.01) were protective against infection. The intersection between WASH and STH infection is complex; site-specific WASH interventions should be considered to sustain the gains made by deworming activities.     

Effect of Poor Access to Water and Sanitation As Risk Factors for Soil-Transmitted Helminth Infection: Selectiveness by the Infective Route

BackgroundSoil-transmitted helminth (STH) infections are a public health problem in resource-limited settings worldwide. Chronic STH infection impairs optimum learning and productivity, contributing to the perpetuation of the poverty-disease cycle. Regular massive drug administration (MDA) is the cardinal recommendation for its control; along with water, sanitation and hygiene (WASH) interventions. The impact of joint WASH interventions on STH infections has been reported; studies on the independent effect of WASH components are needed to contribute with the improvement of current recommendations for the control of STH. The aim of this study is to assess the association of lacking access to water and sanitation with STH infections, taking into account the differences in route of infection among species and the availability of adequate water and sanitation at home.ConclusionsLack of safe water and proper sanitation pose a risk of STH infections that is distinct according to the route of entry to the human host used by each of the STH species. Interventions aimed to improve water and sanitation access should be highlighted in the recommendations for the control of STH.     

The Impact of Water,Sanitation and Hygiene Interventions to Control Cholera: A Systematic Review

Background and Methods

Cholera remains a significant threat to global public health with an estimated 100,000 deaths per year. Water, sanitation and hygiene (WASH) interventions are frequently employed to control outbreaks though evidence regarding their effectiveness is often missing. This paper presents a systematic literature review investigating the function, use and impact of WASH interventions implemented to control cholera.

Results

The review yielded eighteen studies and of the five studies reporting on health impact, four reported outcomes associated with water treatment at the point of use, and one with the provision of improved water and sanitation infrastructure. Furthermore, whilst the reporting of function and use of interventions has become more common in recent publications, the quality of studies remains low. The majority of papers (>60%) described water quality interventions, with those at the water source focussing on ineffective chlorination of wells, and the remaining being applied at the point of use. Interventions such as filtration, solar disinfection and distribution of chlorine products were implemented but their limitations regarding the need for adherence and correct use were not fully considered. Hand washing and hygiene interventions address several transmission routes but only 22% of the studies attempted to evaluate them and mainly focussed on improving knowledge and uptake of messages but not necessarily translating this into safer practices. The use and maintenance of safe water storage containers was only evaluated once, under-estimating the considerable potential for contamination between collection and use. This problem was confirmed in another study evaluating methods of container disinfection. One study investigated uptake of household disinfection kits which were accepted by the target population. A single study in an endemic setting compared a combination of interventions to improve water and sanitation infrastructure, and the resulting reductions in cholera incidence.

Discussion and Recommendations

This review highlights a focus on particular routes of transmission, and the limited number of interventions tested during outbreaks. There is a distinct gap in knowledge of which interventions are most appropriate for a given context and as such a clear need for more robust impact studies evaluating a wider array of WASH interventions, in order to ensure effective cholera control and the best use of limited resources.     

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

Background

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.

Methodology

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 Ascaris lumbricoides, Enterobius vermicularis, hookworm, and Trichuris trichiura 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 Ascaris 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 Trichuris (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 Ascaris, hookworm, and Trichuris, respectively. Finished floors were associated with lower Ascaris 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 Trichuris (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.

Conclusions

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.     

The Relationship between Water,Sanitation and Schistosomiasis: A Systematic Review and Meta-analysis

Background

Access to “safe” water and “adequate” sanitation are emphasized as important measures for schistosomiasis control. Indeed, the schistosomes'' lifecycles suggest that their transmission may be reduced through safe water and adequate sanitation. However, the evidence has not previously been compiled in a systematic review.

Methodology

We carried out a systematic review and meta-analysis of studies reporting schistosome infection rates in people who do or do not have access to safe water and adequate sanitation. PubMed, Web of Science, Embase, and the Cochrane Library were searched from inception to 31 December 2013, without restrictions on year of publication or language. Studies'' titles and abstracts were screened by two independent assessors. Papers deemed of interest were read in full and appropriate studies included in the meta-analysis. Publication bias was assessed through the visual inspection of funnel plots and through Egger''s test. Heterogeneity of datasets within the meta-analysis was quantified using Higgins'' I².

Principal Findings

Safe water supplies were associated with significantly lower odds of schistosomiasis (odds ratio (OR) = 0.53, 95% confidence interval (CI): 0.47–0.61). Adequate sanitation was associated with lower odds of Schistosoma mansoni, (OR = 0.59, 95% CI: 0.47–0.73) and Schistosoma haematobium (OR = 0.69, 95% CI: 0.57–0.84). Included studies were mainly cross-sectional and quality was largely poor.

Conclusions/Significance

Our systematic review and meta-analysis suggests that increasing access to safe water and adequate sanitation are important measures to reduce the odds of schistosome infection. However, most of the studies were observational and quality was poor. Hence, there is a pressing need for adequately powered cluster randomized trials comparing schistosome infection risk with access to safe water and adequate sanitation, more studies which rigorously define water and sanitation, and new research on the relationships between water, sanitation, hygiene, human behavior, and schistosome transmission.     

Integration of Water,Sanitation, and Hygiene for the Prevention and Control of Neglected Tropical Diseases: A Rationale for Inter-Sectoral Collaboration

Improvements of water, sanitation, and hygiene (WASH) infrastructure and appropriate health-seeking behavior are necessary for achieving sustained control, elimination, or eradication of many neglected tropical diseases (NTDs). Indeed, the global strategies to fight NTDs include provision of WASH, but few programs have specific WASH targets and approaches. Collaboration between disease control programs and stakeholders in WASH is a critical next step. A group of stakeholders from the NTD control, child health, and WASH sectors convened in late 2012 to discuss opportunities for, and barriers to, collaboration. The group agreed on a common vision, namely “Disease-free communities that have adequate and equitable access to water and sanitation, and that practice good hygiene.” Four key areas of collaboration were identified, including (i) advocacy, policy, and communication; (ii) capacity building and training; (iii) mapping, data collection, and monitoring; and (iv) research. We discuss strategic opportunities and ways forward for enhanced collaboration between the WASH and the NTD sectors.     

Integrated Schistosomiasis and Soil-Transmitted Helminthiasis Control over Five Years on Kome Island,Tanzania

Integrated control strategies are important for sustainable control of schistosomiasis and soil-transmitted helminthiasis, despite their challenges for their effective implementation. With the support of Good Neighbors International in collaboration with National Institute of Medical Research, Mwanza, Tanzania, integrated control applying mass drug administration (MDA), health education using PHAST, and improved safe water supply has been implemented on Kome Island over 5 years for controlling schistosomiasis and soil-transmitted helminths (STHs). Baseline surveys for schistosomiasis and STHs was conducted before implementation of any integrated control strategies, followed by 4 cross-sectional follow-up surveys on randomly selected samples of schoolchildren and adults in 10 primary schools and 8 villages, respectively, on Kome islands. Those follow-up surveys were conducted for impact evaluation after introduction of control strategies interventions in the study area. Five rounds of MDA have been implemented from 2009 along with PHAST and improved water supply with pumped wells as other control strategies for complementing MDA. A remarkable steady decline of schistosomiasis and STHs was observed from 2009 to 2012 with significant trends in their prevalence decline, and thereafter infection rate has remained at a low sustainable control. By the third follow-up survey in 2012, Schistosoma mansoni infection prevalence was reduced by 90.5% and hookworm by 93.3% among schoolchildren while in adults the corresponding reduction was 83.2% and 56.9%, respectively. Integrated control strategies have successfully reduced S. mansoni and STH infection status to a lower level. This study further suggests that monitoring and evaluation is a crucial component of any large-scale STH and schistosomiasis intervention.     

Effect of Water,Sanitation, and Hygiene on the Prevention of Trachoma: A Systematic Review and Meta-Analysis

Background

Trachoma is the world''s leading cause of infectious blindness. The World Health Organization (WHO) has endorsed the SAFE strategy in order to eliminate blindness due to trachoma by 2020 through “surgery,” “antibiotics,” “facial cleanliness,” and “environmental improvement.” While the S and A components have been widely implemented, evidence and specific targets are lacking for the F and E components, of which water, sanitation, and hygiene (WASH) are critical elements. Data on the impact of WASH on trachoma are needed to support policy and program recommendations. Our objective was to systematically review the literature and conduct meta-analyses where possible to report the effects of WASH conditions on trachoma and identify research gaps.

Methods and Findings

We systematically searched PubMed, Embase, ISI Web of Knowledge, MedCarib, Lilacs, REPIDISCA, DESASTRES, and African Index Medicus databases through October 27, 2013 with no restrictions on language or year of publication. Studies were eligible for inclusion if they reported a measure of the effect of WASH on trachoma, either active disease indicated by observed signs of trachomatous inflammation or Chlamydia trachomatis infection diagnosed using PCR. We identified 86 studies that reported a measure of the effect of WASH on trachoma. To evaluate study quality, we developed a set of criteria derived from the GRADE methodology. Publication bias was assessed using funnel plots. If three or more studies reported measures of effect for a comparable WASH exposure and trachoma outcome, we conducted a random-effects meta-analysis. We conducted 15 meta-analyses for specific exposure-outcome pairs. Access to sanitation was associated with lower trachoma as measured by the presence of trachomatous inflammation-follicular or trachomatous inflammation-intense (TF/TI) (odds ratio [OR] 0.85, 95% CI 0.75–0.95) and C. trachomatis infection (OR 0.67, 95% CI 0.55–0.78). Having a clean face was significantly associated with reduced odds of TF/TI (OR 0.42, 95% CI 0.32–0.52), as were facial cleanliness indicators lack of ocular discharge (OR 0.42, 95% CI 0.23–0.61) and lack of nasal discharge (OR 0.62, 95% CI 0.52–0.72). Facial cleanliness indicators were also associated with reduced odds of C. trachomatis infection: lack of ocular discharge (OR 0.40, 95% CI 0.31–0.49) and lack of nasal discharge (OR 0.56, 95% CI 0.37–0.76). Other hygiene factors found to be significantly associated with reduced TF/TI included face washing at least once daily (OR 0.76, 95% CI 0.57–0.96), face washing at least twice daily (OR 0.85, 95% CI 0.80–0.90), soap use (OR 0.76, 95% CI 0.59–0.93), towel use (OR 0.65, 95% CI 0.53–0.78), and daily bathing practices (OR 0.76, 95% CI 0.53–0.99). Living within 1 km of a water source was not found to be significantly associated with TF/TI or C. trachomatis infection, and the use of sanitation facilities was not found to be significantly associated with TF/TI.

Conclusions

We found strong evidence to support F and E components of the SAFE strategy. Though limitations included moderate to high heterogenity, low study quality, and the lack of standard definitions, these findings support the importance of WASH in trachoma elimination strategies and the need for the development of standardized approaches to measuring WASH in trachoma control programs. Please see later in the article for the Editors'' Summary     

Schistosomiais and Soil-Transmitted Helminth Control in Niger: Cost Effectiveness of School Based and Community Distributed Mass Drug Administration

Background

In 2004 Niger established a large scale schistosomiasis and soil-transmitted helminths control programme targeting children aged 5–14 years and adults. In two years 4.3 million treatments were delivered in 40 districts using school based and community distribution.

Method and Findings

Four districts were surveyed in 2006 to estimate the economic cost per district, per treatment and per schistosomiasis infection averted. The study compares the costs of treatment at start up and in a subsequent year, identifies the allocation of costs by activity, input and organisation, and assesses the cost of treatment. The cost of delivery provided by teachers is compared to cost of delivery by community distributers (CDD).The total economic cost of the programme including programmatic, national and local government costs and international support in four study districts, over two years, was US$ 456,718; an economic cost/treatment of $0.58. The full economic delivery cost of school based treatment in 2005/06 was $0.76, and for community distribution was $0.46. Including only the programme costs the figures are $0.47 and $0.41 respectively. Differences at sub-district are more marked. This is partly explained by the fact that a CDD treats 5.8 people for every one treated in school.The range in cost effectiveness for both direct and direct and indirect treatments is quantified and the need to develop and refine such estimates is emphasised.

Conclusions

The relative cost effectiveness of school and community delivery differs by country according to the composition of the population treated, the numbers targeted and treated at school and in the community, the cost and frequency of training teachers and CDDs. Options analysis of technical and implementation alternatives including a financial analysis should form part of the programme design process.     

Accuracy of Coverage Survey Recall following an Integrated Mass Drug Administration for Lymphatic Filariasis,Schistosomiasis, and Soil-Transmitted Helminthiasis

Background

Achieving target coverage levels for mass drug administration (MDA) is essential to elimination and control efforts for several neglected tropical diseases (NTD). To ensure program goals are met, coverage reported by drug distributors may be validated through household coverage surveys that rely on respondent recall. This is the first study to assess accuracy in such surveys.

Methodology/Principal Findings

Recall accuracy was tested in a series of coverage surveys conducted at 1, 6, and 12 months after an integrated MDA in Togo during which three drugs (albendazole, ivermectin, and praziquantel) were distributed. Drug distribution was observed during the MDA to ensure accurate recording of persons treated during the MDA. Information was obtained for 506, 1131, and 947 persons surveyed at 1, 6, and 12 months, respectively. Coverage (defined as the percentage of persons taking at least one of the MDA medications) within these groups was respectively 88.3%, 87.4%, and 80.0%, according to the treatment registers; it was 87.9%, 91.4% and 89.4%, according to survey responses. Concordance between respondents and registers on swallowing at least one pill was >95% at 1 month and >86% at 12 months; the lower concordance at 12 months was more likely due to difficulty matching survey respondents with the year-old treatment register rather than inaccurate responses. Respondents generally distinguished between pills similar in appearance; concordance for recall of which pills were taken was over 80% in each survey.

Significance

In this population, coverage surveys provided remarkably consistent coverage estimates for up to one year following an integrated MDA. It is not clear if similar consistency will be seen in other settings, however, these data suggest that in some settings coverage surveys might be conducted as much as one year following an MDA without compromising results. This might enable integration of post-MDA coverage measurement into large, multipurpose, periodic surveys, thereby conserving resources.