SEARCHMETA-ANALYSISpublic health, epidemiology

meta-analysis·public health, epidemiology, systematic review, meta-analysis, infectious disease·PMC10009758

Effects of water, sanitation, and hygiene interventions on detection of enteropathogens and host-specific faecal markers in the environment: a systematic review and individual participant data meta-analysis

The Lancet. Planetary Health · 27 authors, 20 centres

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TL;DR

This systematic review and meta-analysis of nine environmental assessments from five WASH trials found that basic sanitation interventions led to a small reduction in the prevalence of any pathogen in environmental samples but had no effect on markers of human or animal faecal contamination.

Full summary

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The pooled analysis showed a small but statistically significant reduction in the prevalence of any pathogen in any sample type (pooled PR 0.94, 95% CI 0.90–0.99). However, interventions had no effect on the prevalence of MST markers from humans (pooled PR 1.00, 95% CI 0.88–1.13) or animals (pooled PR 1.00, 95% CI 0.97–1.03). Individual study effect estimates were often indistinguishable from chance. The authors note that the evaluated interventions did not meet safely managed sanitation standards and suggest these results are consistent with the small or null health effects previously reported in these trials. Limitations include heterogeneity in pathogen targets and low variation in some markers.

STUDY TYPE

meta-analysis

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public health

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ORIGINAL PAPER

PMC10009758

Effects of water, sanitation, and hygiene interventions on detection of enteropathogens and host-specific faecal markers in the environment: a systematic review and individual participant data meta-analysis

The Lancet. Planetary Health

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ABSTRACT

Summary Background Water, sanitation, and hygiene (WASH) improvements are promoted to reduce diarrhoea in low-income countries. However, trials from the past 5 years have found mixed effects of household-level and community-level WASH interventions on child health. Measuring pathogens and host-specific faecal markers in the environment can help investigate causal pathways between WASH and health by quantifying whether and by how much interventions reduce environmental exposure to enteric pathogens and faecal contamination from human and different animal sources. We aimed to assess the effects of WASH interventions on enteropathogens and microbial source tracking (MST) markers in environmental samples. Methods We did a systematic review and individual participant data meta-analysis, which included searches from Jan 1, 2000, to Jan 5, 2023, from PubMed, Embase, CAB Direct Global Health, Agricultural and Environmental Science Database, Web of Science, and Scopus, of prospective studies with water, sanitation, or hygiene interventions and concurrent control group that measured pathogens or MST markers in environmental samples and measured child anthropometry, diarrhoea, or pathogen-specific infections. We used covariate-adjusted regression models with robust standard errors to estimate study-specific intervention effects and pooled effect estimates across studies using random-effects models. Findings Few trials have measured the effect of sanitation interventions on pathogens and MST markers in the environment and they mostly focused on onsite sanitation. We extracted individual participant data on nine environmental assessments from five eligible trials. Environmental sampling included drinking water, hand rinses, soil, and flies. Interventions were consistently associated with reduced pathogen detection in the environment but effect estimates in most individual studies could not be distinguished from chance. Pooled across studies, we found a small reduction in the prevalence of any pathogen in any sample type (pooled prevalence ratio [PR] 0·94 [95% CI 0·90–0·99]). Interventions had no effect on the prevalence of MST markers from humans (pooled PR 1·00 [95% CI 0·88–1·13]) or animals (pooled PR 1·00 [95% CI 0·97–1·03]). Interpretation The small effect of these sanitation interventions on pathogen detection and absence of effects on human or animal faecal markers are consistent with the small or null health effects previously reported in these trials. Our findings suggest that the basic sanitation interventions implemented in these studies did not contain human waste and did not adequately reduce exposure to enteropathogens in the environment. Funding Bill and Melinda Gates Foundation and the UK Foreign and Commonwealth Development Office.

CITATION EXPORT

Andrew Mertens, Benjamin F Arnold, Jade Benjamin-Chung et al.. Effects of water, sanitation, and hygiene interventions on detection of enteropathogens and host-specific faecal markers in the environment: a systematic review and individual participant data meta-analysis. The Lancet. Planetary Health. (2023). https://doi.org/10.1016/S2542-5196(23)00028-1

AUTHORS

27 · 20 CENTRES

Andrew Mertens, Benjamin F Arnold, Jade Benjamin-Chung, Alexandria B Boehm, Joe Brown, Drew Capone, Thomas Clasen, Erica Fuhrmeister, Jessica A Grembi, David Holcomb, Jackie Knee, Laura H Kwong, Audrie Lin, Stephen P Luby, Rassul Nala, Kara Nelson, Sammy M Njenga, Clair Null, Amy J Pickering, Mahbubur Rahman, Heather E Reese, Lauren Steinbaum, Jill Stewart, Ruwan Thilakaratne, Oliver Cumming, John M Colford, Ayse Ercumen

aDivision of Epidemiology and Biostatistics, University of California, Berkeley, CA, USA
bDivision of Environmental Health Sciences, University of California, Berkeley, CA, USA
cDepartment of Civil and Environmental Engineering, College of Engineering, University of California, Berkeley, CA, USA
dFrancis I Proctor Foundation and Department of Ophthalmology, University of California, San Francisco, CA, USA
eDepartment of Epidemiology and Population Health, Stanford University, Stanford, CA, USA
fDepartment of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
gDepartment of Medicine, Stanford University, Stanford, CA, USA
hDivision of Infectious Diseases and Geographic Medicine, Stanford University, Stanford, CA, USA
iDepartment of Environmental Science and Engineering, Gillings School of Global Public Health, Michael Hooker Research Center, University of North Carolina, Chapel Hill, NC, USA
jDepartment of Environmental and Occupational Health, Indiana University Bloomington, Bloomington, IN, USA
kDepartment of Environmental Health, Rollins School of Public Health, Emory University, NE, Atlanta, GA, USA
lDepartment of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
mDepartment of Disease Control, London School of Tropical Medicine & Hygiene, London, UK
nDepartment of Biobehavioral Health, Pennsylvania State University, PA, USA
oMinistério da Saúde, Instituto Nacional de Saúde Maputo, Maputo, Mozambique
pKenya Medical Research Institute, Nairobi, Kenya
qMathematica, Princeton, NJ, USA
rEnvironmental Interventions Unit, Infectious Diseases Division, Dhaka, Bangladesh
sCenter for the Ecology of Infectious Diseases, University of Georgia, Athens, GA, USA
tDepartment of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, USA