Enteric infections are associated with linear growth failure in children. To quantify the association between intestinal inflammation and linear growth failure three commercially available enzyme-linked immunosorbent assays (neopterin [NEO], alpha-anti-trypsin [AAT], and myeloperoxidase [MPO]) were performed in a structured sampling of asymptomatic stool from children under longitudinal surveillance for diarrheal illness in eight countries. Samples from 537 children contributed 1,169 AAT, 916 MPO, and 954 NEO test results that were significantly associated with linear growth. When combined to form a disease activity score, children with the highest score grew 1.08 cm less than children with the lowest score over the 6-month period following the tests after controlling for the incidence of diarrheal disease. This set of affordable non-invasive tests delineates those at risk of linear growth failure and may be used for the improved assessments of interventions to optimize growth during a critical period of early childhood.

SummaryBackgroundEnteropathogen infections in early childhood not only cause diarrhoea but contribute to poor growth. We used molecular diagnostics to assess whether particular enteropathogens were associated with linear growth across seven low-resource settings.MethodsWe used quantitative PCR to detect 29 enteropathogens in diarrhoeal and non-diarrhoeal stools collected from children in the first 2 years of life obtained during the Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) multisite cohort study. Length was measured monthly. We estimated associations between aetiology-specific diarrhoea and subclinical enteropathogen infection and quantity and attained length in 3 month intervals, at age 2 and 5 years, and used a longitudinal model to account for temporality and time-dependent confounding.FindingsAmong 1469 children who completed 2 year follow-up, 35 622 stool samples were tested and yielded valid results. Diarrhoeal episodes attributed to bacteria and parasites, but not viruses, were associated with small decreases in length after 3 months and at age 2 years. Substantial decrements in length at 2 years were associated with subclinical, non-diarrhoeal, infection with Shigella (length-for-age Z score [LAZ] reduction −0·14, 95% CI −0·27 to −0·01), enteroaggregative Escherichia coli (−0·21, −0·37 to −0·05), Campylobacter (−0·17, −0·32 to −0·01), and Giardia (−0·17, −0·30 to −0·05). Norovirus, Cryptosporidium, typical enteropathogenic E coli, and Enterocytozoon bieneusi were also associated with small decrements in LAZ. Shigella and E bieneusi were associated with the largest decreases in LAZ per log increase in quantity per g of stool (−0·13 LAZ, 95% CI −0·22 to −0·03 for Shigella; −0·14, −0·26 to −0·02 for E bieneusi). Based on these models, interventions that successfully decrease exposure to Shigella, enteroaggregative E coli, Campylobacter, and Giardia could increase mean length of children by 0·12–0·37 LAZ (0·4–1·2 cm) at the MAL-ED sites.InterpretationSubclinical infection and quantity of pathogens, particularly Shigella, enteroaggregative E coli, Campylobacter, and Giardia, had a substantial negative association with linear growth, which was sustained during the first 2 years of life, and in some cases, to 5 years. Successfully reducing exposure to certain pathogens might reduce global stunting.FundingBill & Melinda Gates Foundation.

SummaryBackgroundOptimum management of childhood diarrhoea in low-resource settings has been hampered by insufficient data on aetiology, burden, and associated clinical characteristics. We used quantitative diagnostic methods to reassess and refine estimates of diarrhoea aetiology from the Etiology, Risk Factors, and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) cohort study.MethodsWe re-analysed stool specimens from the multisite MAL-ED cohort study of children aged 0–2 years done at eight locations (Dhaka, Bangladesh; Vellore, India; Bhaktapur, Nepal; Naushero Feroze, Pakistan; Venda, South Africa; Haydom, Tanzania; Fortaleza, Brazil; and Loreto, Peru), which included active surveillance for diarrhoea and routine non-diarrhoeal stool collection. We used quantitative PCR to test for 29 enteropathogens, calculated population-level pathogen-specific attributable burdens, derived stringent quantitative cutoffs to identify aetiology for individual episodes, and created aetiology prediction scores using clinical characteristics.FindingsWe analysed 6625 diarrhoeal and 30 968 non-diarrhoeal surveillance stools from 1715 children. Overall, 64·9% of diarrhoea episodes (95% CI 62·6–71·2) could be attributed to an aetiology by quantitative PCR compared with 32·8% (30·8–38·7) using the original study microbiology. Viral diarrhoea (36·4% of overall incidence, 95% CI 33·6–39·5) was more common than bacterial (25·0%, 23·4–28·4) and parasitic diarrhoea (3·5%, 3·0–5·2). Ten pathogens accounted for 95·7% of attributable diarrhoea: Shigella (26·1 attributable episodes per 100 child-years, 95% CI 23·8–29·9), sapovirus (22·8, 18·9–27·5), rotavirus (20·7, 18·8–23·0), adenovirus 40/41 (19·0, 16·8–23·0), enterotoxigenic Escherichia coli (18·8, 16·5–23·8), norovirus (15·4, 13·5–20·1), astrovirus (15·0, 12·0–19·5), Campylobacter jejuni or C coli (12·1, 8·5–17·2), Cryptosporidium (5·8, 4·3–8·3), and typical enteropathogenic E coli (5·4, 2·8–9·3). 86·2% of the attributable incidence for Shigella was non-dysenteric. A prediction score for shigellosis was more accurate (sensitivity 50·4% [95% CI 46·7–54·1], specificity 84·0% [83·0–84·9]) than current guidelines, which recommend treatment only of bloody diarrhoea to cover Shigella (sensitivity 14·5% [95% CI 12·1–17·3], specificity 96·5% [96·0–97·0]).InterpretationQuantitative molecular diagnostics improved estimates of pathogen-specific burdens of childhood diarrhoea in the community setting. Viral causes predominated, including a substantial burden of sapovirus; however, Shigella had the highest overall burden with a high incidence in the second year of life. These data could improve the management of diarrhoea in these low-resource settings.FundingBill & Melinda Gates Foundation.

HighlightsChildren living in these settings had a high prevalence of enteropathogens, high levels of intestinal inflammation, abnormal intestinal permeability, high markers of systemic inflammation, and postnatal acquired linear growth deficits when compared to children living in the US or EuropeThis study contributes empiric evidence to demonstrate that enteric infection alters both fecal markers of inflammation and permeabilityCurrent markers of enteropathy fail to account for a large portion of the observed shortfalls in linear growth in these populations, and markers of systemic inflammation appear as the most promising predictive biomarkers for identifying linear growth failure in childrenEnvironmental enteropathy (EE) is hypothesized as a mediator of growth faltering, but few prospective studies have evaluated pathways linking enteropathogen exposure, intestinal inflammation and permeability, and growth. The MAL-ED study represents a novel analytical framework and explicitly evaluates multiple putative EE pathways in combination and using an unprecedented quantity of data. Despite evidence that gut inflammation and altered gut permeability are frequently present and that associations between enteropathogen exposure and gut dysfunction exist, the observed attributable effects of EE on growth faltering in young children were small.

Individuals in the developing world live in conditions of intense exposure to enteric pathogens due to suboptimal water and sanitation. These environmental conditions lead to alterations in intestinal structure, function, and local and systemic immune activation that are collectively referred to as environmental enteropathy (EE). This condition, although poorly defined, is likely to be exacerbated by undernutrition as well as being responsible for permanent growth deficits acquired in early childhood, vaccine failure, and loss of human potential. This article addresses the underlying theoretical and analytical frameworks informing the methodology proposed by the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) cohort study to define and quantify the burden of disease caused by EE within a multisite cohort. Additionally, we will discuss efforts to improve, standardize, and harmonize laboratory practices within the MAL-ED Network. These efforts will address current limitations in the understanding of EE and its burden on children in the developing world.

BackgroundAlthough diarrheal illnesses are recognized as both a cause and effect of undernutrition, evidence for the effect of specific enteropathogens on early childhood growth remains limited. We estimated the effects of undernutrition as a risk factor for campylobacteriosis, as well as associations between symptomatic and asymptomatic Campylobacter infections and growth.Methodology/Principal FindingsUsing data from a prospective cohort of 442 children aged 0–72 months, the effect of nutritional status on the incidence of Campylobacter infection was estimated using uni- and multivariate Poisson models. Multivariate regression models were developed to evaluate the effect of Campylobacter infection on weight gain and linear growth. Overall, 8.3% of diarrheal episodes were associated with Campylobacter (crude incidence rate = 0.37 episodes/year) and 4.9% of quarterly asymptomatic samples were Campylobacter positive. In univariate models, the incidence of Campylobacter infection was marginally higher in stunted than non-stunted children (IRR 1.270, 95% CI (0.960, 1.681)(p = 0.095). When recent diarrheal burdens were included in the analysis, there was no difference in risk between stunted and unstunted children. Asymptomatic and symptomatic Campylobacter infections were associated with reduced weight gain over a three-month period (65.5 g (95% CI: −128.0, −3.0)(p = 0.040) and 43.9 g (95% CI:−87.6, −1.0)(p = 0.049) less weight gain, respectively). Symptomatic Campylobacter infections were only marginally associated with reduced linear growth over a nine month period (−0.059 cm per episode, 95% CI: −0.118, 0.001)(p = 0.054), however relatively severe episodes were associated with reduced linear growth (−0.169 cm/episode, 95% CI −0.310, −0.028)(p = 0.019).Conclusions/SignificanceOur findings suggest that Campylobacter is not as benign as commonly assumed, and that there is evidence to support expanding the indications for antibiotic therapy in campylobacteriosis in children.

Our findings suggest that associations between enteropathogen-specific diarrheal episodes and growth, particularly Shigella, are comparable across geographic and epidemiological contexts.

The Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) cohort study communities in Peru are located in Loreto province, in a rural area 15 km from the city of Iquitos. This riverine population of approximately 5000 individuals is fairly representative of Loreto. The province lags behind the rest of the country in access to water and sanitation, per capita income, and key health indicators including infant mortality (43.0 vs 16.0 per 1000 nationwide) and under-5 mortality (60.6 vs 21.0 per 1000). Total fertility rates are higher than elsewhere in the country (4.3 vs 2.6). Nationwide, the prevalence of human immunodeficiency virus is estimated at 0.45%, the prevalence of tuberculosis is 117 per 100 000, and the incidence of malaria is 258 per 100 000. Stunting in this community is high, whereas acute undernutrition is relatively uncommon. The population suffers from high rates of diarrheal disease. Prevalent enteric pathogens include Ascaris, Giardia, enterotoxigenic Escherichia coli, Shigella, and Campylobacter.