Research Article: Association between Footwear Use and Neglected Tropical Diseases: A Systematic Review and Meta-Analysis

Date Published: November 13, 2014

Publisher: Public Library of Science

Author(s): Sara Tomczyk, Kebede Deribe, Simon J. Brooker, Hannah Clark, Khizar Rafique, Stefanie Knopp, Jürg Utzinger, Gail Davey, Jeffrey Michael Bethony.

Abstract: BackgroundThe control of neglected tropical diseases (NTDs) has primarily focused on preventive chemotherapy and case management. Less attention has been placed on the role of ensuring access to adequate water, sanitation, and hygiene and personal preventive measures in reducing exposure to infection. Our aim was to assess whether footwear use was associated with a lower risk of selected NTDs.MethodologyWe conducted a systematic review and meta-analysis to assess the association between footwear use and infection or disease for those NTDs for which the route of transmission or occurrence may be through the feet. We included Buruli ulcer, cutaneous larva migrans (CLM), leptospirosis, mycetoma, myiasis, podoconiosis, snakebite, tungiasis, and soil-transmitted helminth (STH) infections, particularly hookworm infection and strongyloidiasis. We searched Medline, Embase, Cochrane, Web of Science, CINAHL Plus, and Popline databases, contacted experts, and hand-searched reference lists for eligible studies. The search was conducted in English without language, publication status, or date restrictions up to January 2014. Studies were eligible for inclusion if they reported a measure of the association between footwear use and the risk of each NTD. Publication bias was assessed using funnel plots. Descriptive study characteristics and methodological quality of the included studies were summarized. For each study outcome, both outcome and exposure data were abstracted and crude and adjusted effect estimates presented. Individual and summary odds ratio (OR) estimates and corresponding 95% confidence intervals (CIs) were calculated as a measure of intervention effect, using random effects meta-analyses.Principal FindingsAmong the 427 studies screened, 53 met our inclusion criteria. Footwear use was significantly associated with a lower odds of infection of Buruli ulcer (OR = 0.15; 95% CI: 0.08–0.29), CLM (OR = 0.24; 95% CI: 0.06–0.96), tungiasis (OR = 0.42; 95% CI: 0.26–0.70), hookworm infection (OR = 0.48; 95% CI: 0.37–0.61), any STH infection (OR = 0.57; 95% CI: 0.39–0.84), strongyloidiasis (OR = 0.56; 95% CI: 0.38–0.83), and leptospirosis (OR = 0.59; 95% CI: 0.37–0.94). No significant association between footwear use and podoconiosis (OR = 0.63; 95% CI: 0.38–1.05) was found and no data were available for mycetoma, myiasis, and snakebite. The main limitations were evidence of heterogeneity and poor study quality inherent to the observational studies included.Conclusions/SignificanceOur results show that footwear use was associated with a lower odds of several different NTDs. Access to footwear should be prioritized alongside existing NTD interventions to ensure a lasting reduction of multiple NTDs and to accelerate their control and elimination.Protocol RegistrationPROSPERO International prospective register of systematic reviews CRD42012003338

Partial Text: Neglected tropical diseases (NTDs) are caused by a variety of pathogens, such as parasites (e.g., ectoparasites, helminths, and protozoa), fungi, bacteria, and viruses, primarily found in the tropical and subtropical regions of the world [1]. NTDs mainly occur in rural and deprived urban areas of low- and middle-income countries, where they may exacerbate poverty by contributing to significant morbidity and mortality, impairing development, and limiting productivity [1], [2]. They have multiple routes of transmission and a single intervention alone is unlikely to have major sustained impact. Population-based chemotherapy is currently the mainstay of the control of various NTDs caused by helminths (e.g., lymphatic filariasis, schistosomiasis, and soil-transmitted helminth (STH) infections) and some bacterial infections (e.g., trachoma) [3], [4]. More recently, attention has been given to water, sanitation, and hygiene (WASH) as an effective and sustainable measure for NTD control [5]–[7]. WASH interventions such as face washing to prevent trachoma, or hand washing to prevent diarrheal diseases and STH infection have been well-studied [8]–[10]. However, less attention has focused on other personal preventive measures to reduce exposure to infection, such as the use of footwear. Some NTDs may be transmitted or occur through the feet, and hence, footwear could prevent this exposure. To our knowledge, there has not yet been a systematic review of the evidence to assess the role of footwear use among these NTDs [8]–[12].

NTDs were selected to be included in the study based on disease etiology and potential for infection through the feet and thus prevention using footwear (Table 1). A systematic literature review protocol strategy was developed based on the ‘Preferred Reporting Items for Systematic reviews and Meta-Analyses’ (PRISMA) checklist (e.g., protocol and registration, eligibility criteria, information sources, searching, study selection, data collection process, data items, risk of bias in individual studies, summary measures, synthesis of results, risk of bias across studies, and additional analyses (see: Checklist S1). This protocol is available at the National Institute for Health Research PROSPERO International prospective register of systematic reviews (identifier: CRD42012003338) (see Protocol S1).

The electronic searches generated 427 citations and abstracts. These were screened and 374 were excluded for a range of reasons (Figure 1). We included 53 sources: Buruli ulcer (n = 3), CLM (n = 1), leptospirosis (n = 7), podoconiosis (n = 6), any STH infections (n = 11), hookworm infection (n = 17), strongyloidiasis (n = 4), and tungiasis (n = 4). No data were found to quantify the association between footwear use and mycetoma, myiasis, and snakebite. Type of source included 50 journal manuscripts (94.3%), two unpublished pieces of work (3.8%), and one book excerpt (1.9%). Information describing the studies included are summarized in Table 2, including study design, publication year, country and outcome. We identified a total of 40 cross-sectional studies (75.4%), eight case-control studies (15.1%), three cohort studies (5.7%), and two RCTs (3.8%). The median publication year was 2003 (range: 1950–2014). Geographically, 29 studies were conducted in Africa (54.7%), 12 in Asia (22.6%), 11 in the Americas (20.8%), and one in Europe (1.9%). The median sample size was 366 individuals (range: 59–129,959). Among the 11 studies with known follow-up periods, the median follow-up time was 12 months (range: 2.5 months to 7 years). Descriptive results by individual studies including sample size, median age, and proportion of females are shown in Table 2. A summary of descriptive results by outcome, including study quality results, are provided in Table 3.

We found that footwear use was significantly associated with a lower odds of Buruli ulcer, CLM, leptospirosis, strongyloidiasis, any STH infection, hookworm infection, and tungiasis, highlighting the important role of footwear use in the prevention of NTDs. No significant association was found between footwear use and podoconiosis. We found no data regarding the use footwear and mycetoma, myiasis, and snakebite. The results presented here have important implications for both policy and practice. Promotion of footwear use should be an important part of selected NTD control strategies.



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