Response to 'The implications of three major new trials for the effect of water, sanitation and hygiene on childhood diarrhea and stunting: a consensus statement' by Cumming et al

Water, sanitation, and hygiene global research: evolution, trends, and knowledge structure

Water, sanitation, and hygiene (WASH) services play a crucial role in promoting public and environmental health as well as social and economic development. At the global level, particularly in the developing world, WASH issues continue to present significant challenges. These challenges have been further intensified by factors such as the COVID-19 pandemic, escalating conflicts, climate change, water scarcity, and rising inequality. The scientific community has actively engaged in constructive discussions on these issues, as evidenced by the notable research findings. Therefore, the aim of this study was to comprehensively examine and evaluate global knowledge on WASH. To search for relevant publications, the Scopus database was utilized using specific terms associated with WASH. VOSviewer 1.6.18 software was employed to generate network visualization maps, which assessed collaborative patterns and research trends in the field of WASH. The research output of countries was adjusted considering their gross domestic product (GDP) and population size. The total number of WASH-related publications, including all types of documents, was 1805. By narrowing the search to articles and reviews, the overall global productivity yielded 1589 documents: 1367 (86.0%) original articles and 222 (14.0%) review articles. The USA had the highest number of WASH publications (n = 668; 42.0%), followed by the UK (n = 396; 24.9%), Switzerland (n = 151; 9.5%), and Australia (n = 141; 8.9%). Ethiopia emerged as the leading country in terms of GDP per capita and the number of publications, followed by Uganda, Malawi, India, and Bangladesh. The USA, the UK, and Switzerland exhibited the most extensive collaboration among countries. The main research areas encompassed the role of WASH in sustainable development, the impacts of inadequate access to WASH services on gender equality, children, infants, and the outbreak of COVID-19 and other diseases, as well as the significance of hygiene practices and community and school-based WASH interventions in reducing infections. This study provides a novel analysis of global WASH-related research and highlights the distribution of outcomes across nations. Continued and increased collaboration between developed and developing nations will facilitate the sharing of responsibility for WASH research outcomes and the implementation of effective policies.

Protocol for the PATHOME study: a cohort study on urban societal development and the ecology of enteric disease transmission among infants, domestic animals and the environment

INTRODUCTION

Global morbidity from enteric infections and diarrhoea remains high in children in low-income and middle-income countries, despite significant investment over recent decades in health systems and water and sanitation infrastructure. Other types of societal development may be required to reduce disease burden. Ecological research on the influence of household and neighbourhood societal development on pathogen transmission dynamics between humans, animals and the environment could identify more effective strategies for preventing enteric infections.

METHODS AND ANALYSIS

The 'enteric pathome'-that is, the communities of viral, bacterial and parasitic pathogens transmitted from human and animal faeces through the environment is taxonomically complex in high burden settings. This integrated cohort-exposure assessment study leverages natural socioeconomic spectrums of development to study how pathome complexity is influenced by household and neighbourhood infrastructure and hygiene conditions. We are enrolling under 12-month-old children in low-income and middle-income neighbourhoods of two Kenyan cities (Nairobi and Kisumu) into a 'short-cohort' study involving repeat testing of child faeces for enteric pathogens. A mid-study exposure assessment documenting infrastructural, behavioural, spatial, climate, environmental and zoonotic factors characterises pathogen exposure pathways in household and neighbourhood settings. These data will be used to inform and validate statistical and agent-based models (ABM) that identify individual or combined intervention strategies for reducing multipathogen transmission between humans, animals and environment in urban Kenya.

ETHICS AND DISSEMINATION

The protocols for human subjects' research were approved by Institutional Review Boards at the University of Iowa (ID-202004606) and AMREF Health Africa (ID-ESRC P887/2020), and a national permit was obtained from the Kenya National Commission for Science Technology and Innovation (ID# P/21/8441). The study was registered on Clinicaltrials.gov (Identifier: NCT05322655) and is in pre-results stage. Protocols for research on animals were approved by the University of Iowa Animal Care and Use Committee (ID 0042302).

Study design and rationale for the PAASIM project: a matched cohort study on urban water supply improvements and infant enteric pathogen infection, gut microbiome development and health in Mozambique

INTRODUCTION

Despite clear linkages between provision of clean water and improvements in child health, limited information exists about the health impacts of large water infrastructure improvements in low-income settings. Billions of dollars are spent annually to improve urban water supply, and rigorous evaluation of these improvements, especially targeting informal settlements, is critical to guide policy and investment strategies. Objective measures of infection and exposure to pathogens, and measures of gut function, are needed to understand the effectiveness and impact of water supply improvements.

METHODS AND ANALYSIS

In the PAASIM study, we examine the impact of water system improvements on acute and chronic health outcomes in children in a low-income urban area of Beira, Mozambique, comprising 62 sub-neighbourhoods and ~26 300 households. This prospective matched cohort study follows 548 mother-child dyads from late pregnancy through 12 months of age. Primary outcomes include measures of enteric pathogen infections, gut microbiome composition and source drinking water microbiological quality, measured at the child's 12-month visit. Additional outcomes include diarrhoea prevalence, child growth, previous enteric pathogen exposure, child mortality and various measures of water access and quality. Our analyses will compare (1) subjects living in sub-neighbourhoods with the improved water to those living in sub-neighbourhoods without these improvements; and (2) subjects with household water connections on their premises to those without such a connection. This study will provide critical information to understand how to optimise investments for improving child health, filling the information gap about the impact of piped water provision to low-income urban households, using novel gastrointestinal disease outcomes.

ETHICS AND DISSEMINATION

This study was approved by the Emory University Institutional Review Board and the National Bio-Ethics Committee for Health in Mozambique. The pre-analysis plan is published on the Open Science Framework platform (https://osf.io/4rkn6/). Results will be shared with relevant stakeholders locally, and through publications.

Exposure to household air pollution from solid cookfuels and childhood stunting: a population-based, cross-sectional study of half a million children in low- and middle-income countries

BACKGROUND

Household air pollution from the incomplete combustion of solid cookfuels in low- and middle-income countries (LMICs) has been largely ignored as a potentially important correlate of stunting. Our objective was to examine the association between solid cookfuel use and stunting in children aged <5 y.

METHODS

We used data from 59 LMICs' population-based cross-sectional demographic and health surveys; 557 098 children aged <5 y were included in our analytical sample. Multilevel logistic regression was used to examine the association between exposure to solid cookfuel use and childhood stunting, adjusting for child sex, age, maternal education and number of children living in the household. We explored the association across key subgroups.

RESULTS

Solid cookfuel use was associated with child stunting (adjusted OR 1.58, 95% CI 1.55 to 1.61). Children living in households using solid cookfuels were more likely to be stunted if they lived in rural areas, the poorest households, had a mother who smoked tobacco or were from the Americas.

CONCLUSIONS

Focused strategies to reduce solid cookfuel exposure might contribute to reductions in childhood stunting in LMICs. Trial evidence to assess the effect of reducing solid cookfuel exposure on childhood stunting is urgently needed.

Household flooring associated with reduced infant diarrhoeal illness in Zimbabwe in households with and without WASH interventions

OBJECTIVES

Diarrhoeal illness is a leading cause of childhood morbidity and mortality and has long-term negative impacts on child development. Although flooring, water and sanitation have been identified as important routes of transmission of diarrhoeal pathogens, research examining variability in the association between flooring and diarrhoeal illness by water and sanitation is limited.

METHODS

We utilised cross-sectional data collected for the evaluation of Zimbabwe's Prevention of Mother-to-Child HIV transmission programme in 2014 and 2017-18. Mothers of infants 9-18 months of age self-reported the household's source of drinking water and type of sanitation facility, as well as infant diarrhoeal illness in the four weeks prior to the survey. Household flooring was assessed using interviewer observation, and households in which the main material of flooring was dirt/earthen were classified as having unimproved flooring, and those with solid flooring (e.g. cement) were classified as having improved flooring.

RESULTS

Mothers of infants living in households with improved flooring were less likely to report diarrhoeal illness in the last four weeks (PD_a  = -4.8%, 95% CI: -8.6, -1.0). The association between flooring and diarrhoeal illness did not vary by the presence of improved/unimproved water (p_RERI  = 0.91) or sanitation (p_RERI  = 0.76).

CONCLUSIONS

Our findings support the hypothesis that household flooring is an important pathway for the transmission of diarrhoeal pathogens, even in settings where other aspects of sanitation are sub-optimal. Improvements to household flooring do not require behaviour change and may be an effective and expeditious strategy for reducing childhood diarrhoeal illness irrespective of household access to improved water and sanitation.

Tackling the triple threats of childhood malnutrition

The term 'double burden of malnutrition' is usually interpreted in terms of the physical status of children: stunted and wasted children on the one hand and overweight/obese children on the other. There is a third category of malnutrition that can occur at either end of the anthropometric spectrum or, indeed, in children whose physical size may be close to ideal. This third type is most commonly articulated with the phrase 'hidden hunger' and is often illustrated by micronutrient deficiencies; thus, we refer to it here as 'undernutrition'. As understanding of such issues advances, we realise that there is a myriad of factors that may be influencing a child's road to nutritional health. In this BMC Medicine article collection we consider these influences and the impact they have, such as: the state of the child's environment; the effect this has on their risk of, and responses to, infection and on their gut; the consequences of poor nutrition on cognition and brain development; the key drivers of the obesity epidemic across the globe; and how undernourishment can affect a child's body composition. This collection showcases recent advances in the field, but likewise highlights ongoing challenges in the battle to achieve adequate nutrition for children across the globe.