Assessment of aflatoxin exposure, growth faltering and the gut microbiome among children in rural Guatemala: protocol for an observational prospective cohort and bioreactor simulations.

INTRODUCTION: Aflatoxin B1 (AFB1) is a carcinogen produced by Aspergillus flavus and Aspergillus parasiticus which grow on maize. Given the high prevalence of child stunting (ie, impaired growth) and other nutritional disorders in low-income and middle-income countries, where maize is consumed, the role of aflatoxin exposure may be significant. Observational reports have demonstrated associations between aflatoxin exposure and impaired child growth; however, most have been cross-sectional and have not assessed seasonal variations in aflatoxin, food preparation and dynamic changes in growth. Biological mechanistic data on how aflatoxin may exert an impact on child growth is missing. This study incorporates a prospective cohort of children from rural Guatemala to assess (1) temporal associations between aflatoxin exposure and child growth and (2) possible mediation of the gut microbiome among aflatoxin exposure, inflammation and child growth. METHODS AND ANALYSIS: We will prospectively evaluate aflatoxin exposure and height-for-age difference trajectories for 18 months in a cohort of 185 children aged 6-9 months at enrolment. We will assess aflatoxin exposure levels and biomarkers of gut and systemic inflammation. We will examine the faecal microbiome of each child and identify key species and metabolic pathways for differing AFB1 exposure levels and child growth trajectories. In parallel, we will use bioreactors, inoculated with faeces, to investigate the response of the gut microbiome to varying levels of AFB1 exposure. We will monitor key microbial metabolites and AFB1 biotransformation products to study nutrient metabolism and the impact of the gut microbiome on aflatoxin detoxification/metabolism. Finally, we will use path analysis to summarise the effect of aflatoxin exposure and the gut microbiome on child growth. ETHICS AND DISSEMINATION: Ethics approval was obtained from Arizona State University Institutional Review Board (IRB; STUDY00016799) and Wuqu' Kawoq/Maya Health Alliance IRB (WK-2022-003). Findings will be disseminated in scientific presentations and peer-reviewed publications.

Microbial Characterization, Factors Contributing to Contamination, and Household Use of Cistern Water, U.S. Virgin Islands.

Households in the United States Virgin Islands (USVI) heavily rely on roof-harvested rainwater stored in cisterns for their daily activities. However, there are insufficient data on cistern water microbiological and physicochemical characteristics to inform appropriate cistern water management. Cistern and kitchen tap water samples were collected from 399 geographically representative households across St. Croix, St. Thomas, and St. John and an administered survey captured household site and cistern characteristics and water use behaviors. Water samples were analyzed for Escherichia coli by culture, and a subset of cistern water samples (N = 47) were analyzed for Salmonella, Naegleria fowleri, pathogenic Leptospira, Cryptosporidium, Giardia, and human-specific fecal contamination using real-time polymerase chain reaction (PCR). Associations between E. coli cistern contamination and cistern and site characteristics were evaluated to better understand possible mechanisms of contamination. E. coli was detected in 80% of cistern water samples and in 58% of kitchen tap samples. For the subset of samples tested by PCR, at least one of the pathogens was detected in 66% of cisterns. Our results suggest that covering overflow pipes with screens, decreasing animal presence at the household, and preventing animals or insects from entering the cisterns can decrease the likelihood of E. coli contamination in USVI cistern water.

Passive In-Line Chlorination for Drinking Water Disinfection: A Critical Review.

The world is not on track to meet Sustainable Development Goal 6.1 to provide universal access to safely managed drinking water by 2030. Removal of priority microbial contaminants by disinfection is one aspect of ensuring water is safely managed. Passive chlorination (also called in-line chlorination) represents one approach to disinfecting drinking water before or at the point of collection (POC), without requiring daily user input or electricity. In contrast to manual household chlorination methods typically implemented at the point of use (POU), passive chlorinators can reduce the user burden for chlorine dosing and enable treatment at scales ranging from communities to small municipalities. In this review, we synthesized evidence from 27 evaluations of passive chlorinators (in 19 articles, 3 NGO reports, and 5 theses) conducted across 16 countries in communities, schools, health care facilities, and refugee camps. Of the 27 passive chlorinators we identified, the majority (22/27) were solid tablet or granular chlorine dosers, and the remaining devices were liquid chlorine dosers. We identified the following research priorities to address existing barriers to scaled deployment of passive chlorinators: (i) strengthening local chlorine supply chains through decentralized liquid chlorine production, (ii) validating context-specific business models and financial sustainability, (iii) leveraging remote monitoring and sensing tools to monitor real-time chlorine levels and potential system failures, and (iv) designing handpump-compatible passive chlorinators to serve the many communities reliant on handpumps as a primary drinking water source. We also propose a set of reporting indicators for future studies to facilitate standardized evaluations of the technical performance and financial sustainability of passive chlorinators. In addition, we discuss the limitations of chlorine-based disinfection and recognize the importance of addressing chemical contamination in drinking water supplies. Passive chlorinators deployed and managed at-scale have the potential to elevate the quality of existing accessible and available water services to meet "safely managed" requirements.

Rethinking water, sanitation, and hygiene for human growth and development.

Life history theory emphasises plasticity in developmental and biological programming where conditions in early life, lead to long-term consequences for health and wellbeing. Studies linking water, sanitation, and hygiene, nutrition, and child growth and development have emphasised the optimisation of linear growth as a key metric for the evaluation of intervention efficacy. Life history characteristics pertaining to human growth and phenotypic plasticity, suggest that different developmental outcomes in early childhood may be responsive to different stimuli at different ages. Energy utilisation by the human brain, from birth through childhood, accounts for a disproportionate percentage of the resting metabolic rate. Undernutrition in early life, and its relative resultant energy deficiency, may trigger adaptive physiological mechanisms prioritising brain growth at the expense of body growth. Emphasis placed on linear growth may have impeded the significance of WASH due to excluding aspects of child development beyond height/weight. We propose that incorporating evolutionary public health and life history theory perspectives, allows for the identification of age-appropriate biological outcomes and WASH indicators, while anticipating the timing and life-course suitability of the interventions being operationalised. Finally, integrating reflections regarding context allows for the development of transformative WASH interventions.

The influence of local market and household factors on aflatoxin presence in maize and symptoms of its exposure to children in Guatemala.

Recent evidence supports the hypothesis that aflatoxin exposure from maize can influence malnutrition rates among children. Therefore, in Guatemala we investigated two questions; which maize sources exposed households to higher risk of aflatoxin exposure symptoms and what the risk factors were for each maize source, pre- and post-maize harvest. Survey data and household maize samples were collected in October 2016 (pre-harvest) and February 2017 (post-harvest) in San Vicente, Guatemala. Structural equation modeling (SEM) and odds ratios were used to assess the data. The results suggested that households which purchased maize from the market had 3.64 higher odds of high levels of aflatoxin. The models identified that good market purchase habits were significant for market-based maize sources while improved post-harvest practices and improved types of maize storage were significant for subsistence-based maize sources. Cumulative results suggest multiple interventions may be effective but are dependent on time of year and source of maize.

Assessment of environmental exposure factors on child diarrhea and systemic inflammation in the Eastern Cape.

Poor environmental technologies and gastrointestinal illnesses have been hypothesized to be a primary cause to the lack of impact of child health programs on child stunting rates (low height-for-age) in South Africa. This study assessed correlations between environmental exposures (water source, water treatment, sanitation, refuse), diarrheal occurrences, and systemic inflammation proxies among female and male children under five years of age in the Eastern Cape. A conceptual model was hypothesized using structural equation (SE) modeling and two sex-specific (female and male) datasets were subsequently generated from the data and applied to the hypothesized SE model. Results suggested that environmental exposure variables associated with diarrhea and systemic inflammation proxies were different between females and males. For diarrheal occurrences among females, an increase in local authority management of refuse (compared to household management) (0.161, p-value (p) = 0.007), sharing sanitation facilities (0.060, p = 0.023), and a decrease in the frequency of the treatment of drinking water (-0.043, p = 0.025) were correlated with an increase in diarrhea. For males, an increase in household use of flush toilets (as compared to ventilated pit latrines) was correlated with an increase in diarrhea (0.113, p = 0.027). For systemic inflammation among both sexes, an increase in household use of water pumped into the premises (as compared to a public water tap) and an increase in diarrheal occurrences were correlated with an increase in systemic inflammation. The data support an increased focus on sex and gender specific factors among field practitioners and policy makers working in the environmental health field in South Africa.

Association of aflatoxin exposure and height-for-age among young children in Guatemala.

Aflatoxin exposure has been proposed to affect child height-for-age. The following hypothesized associations were tested in Guatemala: (1) aflatoxin (B1, B2, G1, G2) exposure and environmental enteric dysfunction (EED) and child height-for-age z-score; and (2) aflatoxin exposures and subsequent symptoms of aflatoxins. Maize consumption data, health data, and samples of maize from households were collected from mothers and their children - under five - in October 2016 (n = 320) and February 2017 (n = 120). Maize samples were tested for aflatoxin levels and maize consumption data were used to compute an aflatoxin exposure level. Results suggest that there was a significant negative correlation between the putative aflatoxin exposure level and child height-for-age z-score (-0.073, p = 0.030), but not for EED. Furthermore, aflatoxin exposure was significantly correlated with aflatoxin symptoms only at the same time point (0.123, p = 0.026). These results support the potential need for engineered solutions to household aflatoxin transmission problems in rural communities of Guatemala.

What causes childhood stunting among children of San Vicente, Guatemala: Employing complimentary, system-analysis approaches.

Guatemala has the sixth worst stunting rate with 48% of children under five years of age classified as stunted according to World Health Organization standards. This study utilizes two different yet complimentary system-analysis approaches to analyze correlations among environmental and demographic variables, environmental enteric dysfunction (EED), and child height-for-age (stunting metric) in Guatemala. Two descriptive models constructed around applicable environmental and demographic factors on child height-for-age and EED were analyzed using Network Analysis (NA) and Structural Equation Modeling (SEM). Data from two populations of children between the age of three months and five years were used. The first population (n = 2103) was drawn from the Food for Peace Baseline Survey conducted by the US Agency for International Development (USAID) in 2012, and the second population (n = 372) was drawn from an independent survey conducted by the San Vicente Health Center in 2016. The results from the NA of the height-for-age model confirmed pathogen exposure, nutrition, and prenatal health as important, and the results from the NA of the EED model confirmed water source, water treatment, and type of sanitation as important. The results from the SEM of the height-for-age model confirmed a statistically significant correlation among child height-for-age and child-mother interaction (-0.092, p = 0.076) while the SEM of the EED model confirmed the statistically significant correlation among EED and type of water treatment (-0.115, p = 0.013). Our approach supports important efforts to understand the complex set of factors associated with child stunting among communities sharing similarities with San Vicente.