Environmental enteropathy (EE), the adverse impact of frequent and numerous enteric infections on the gut resulting in a state of persistent immune activation and altered permeability, has been proposed as a key determinant of growth failure in children in low- and middle-income populations. A theory-driven systems model to critically evaluate pathways through which enteropathogens, gut permeability, and intestinal and systemic inflammation affect child growth was conducted within the framework of the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) birth cohort study that included children from eight countries. Non-diarrheal stool samples (N=22,846) from 1253 children from multiple sites were evaluated for a panel of 40 enteropathogens and fecal concentrations of myeloperoxidase, alpha-1-antitrypsin, and neopterin. Among these same children, urinary lactulose:mannitol (L:M) (N=6363) and plasma alpha-1-acid glycoprotein (AGP) (N=2797) were also measured. The temporal sampling design was used to create a directed acyclic graph of proposed mechanistic pathways between enteropathogen detection in non-diarrheal stools, biomarkers of intestinal permeability and inflammation, systemic inflammation and change in length- and weight- for age in children 0-2years of age. Children in these populations had frequent enteric infections and high levels of both intestinal and systemic inflammation. Higher burdens of enteropathogens, especially those categorized as being enteroinvasive or causing mucosal disruption, were associated with elevated biomarker concentrations of gut and systemic inflammation and, via these associations, indirectly associated with both reduced linear and ponderal growth. Evidence for the association with reduced linear growth was stronger for systemic inflammation than for gut inflammation; the opposite was true of reduced ponderal growth. Although Giardia was associated with reduced growth, the association was not mediated by any of the biomarkers evaluated. The large quantity of empirical evidence contributing to this analysis supports the conceptual model of EE. The effects of EE on growth faltering in young children were small, but multiple mechanistic pathways underlying the attribution of growth failure to asymptomatic enteric infections had statistical support in the analysis. The strongest evidence for EE was the association between enteropathogens and linear growth mediated through systemic inflammation. Bill & Melinda Gates Foundation.

Entamoeba histolytica, Giardia intestinalis, and Cryptosporidium spp. are not only three of the most important and common diarrhea-causing parasitic protozoa, but they often have similar clinical presentations. Microscopic diagnosis of these parasites is neither sensitive nor specific. Recently, more specific and sensitive alternative molecular methods (polymerase chain reaction [PCR] and antigen detection tests) have been introduced for all three of these parasitic infections. The use of these molecular diagnostic tests in routine diagnostic laboratories is still limited. In this study, we developed a multiplex real-time PCR assay for the simultaneous detection of E. histolytica, G. intestinalis, and Cryptosporidium spp. in one reaction using species-specific probes. This assay was evaluated using clinical specimens and was found to be quite sensitive and specific. The reagents used in this multiplex PCR assay can also be used for detection of these parasites individually. The use of this real-time PCR multiplex assay in developing countries at present will have limited scope for routine diagnosis because the cost will be high for a single test, although in the developed world, the test could see immediate application.

The transmission soil transmitted helminths (STH) occurs via ingestion of or contact with infective stages present in soil contaminated with human faeces. It follows therefore that efforts to reduce faecal contamination of the environment should help to reduce risk of parasite exposure and improvements in water, sanitation and hygiene (WASH) are seen as essential for the long-term, sustainable control of STH. However, the link between WASH and STH is not always supported by the available evidence from randomised controlled trials, which report mixed effects of WASH intervention on infection risk. This review critically summarises the available trial evidence and offers an interpretation of the observed heterogeneity in findings. The review also discusses the implications of findings for control programmes and highlights three main issues which merit further consideration: intervention design, exposure assessment, and intervention fidelity assessment.

The epidemiology, clinical features, nutritional status, and causative agents of diarrhea were studied in 289 Bangladeshi children (147 boys and 142 girls) 2–5 years old. The use of improved diagnostic tests for amebiasis enabled for the first time analysis of the contribution of Entamoeba histolytica to total diarrheal illness in this community setting. The average incidence rate of diarrhea was 1.8/child-year, and the average number of diarrheal days was 3.7 days/child-year over an average observation period of 2.8 years/child. Seventy-five percent of the diarrheal episodes were ≤ 2 days in duration. Persistent diarrhea was relatively uncommon (0.2% of the children) and chronic diarrhea was observed in only one episode. Compared with malnourished and/or stunted children, better-nourished children experienced significantly fewer diarrheal episodes. The diarrheal incidence rate for children with blood group A was significantly less that that of the children with blood groups O and AB. The most frequent bacterial enteropathogens isolated from diarrheal stool specimens were enterotoxigenic Escherichia coli (9%) and Aeromonas species (9%), followed by Plesimonas shigelloides (4%) and Shigella flexneri (3.8%). Rotavirus was the most common viral agent isolated from diarrheal stool samples (5%). Giardia lamblia, Cryptosporidium parvum, and E. histolytica were identified in 11%, 8.4%, and 8%, respectively, of the diarrheal stool specimens. Dysentery was observed in 7.7% of all diarrheal episodes. The most common pathogens isolated from dysenteric stool were S. flexneri (11.6%), Aeromonas sp. (10%), E. histolytica (8.7%), Campylobacter jejunii (5.8%), P. shigelloides (4.3%), and A. caviae (4.3%). The overall incidence rate of E. histolytica-associated diarrhea was 0.08/child-year. Visible blood and hemoccult test-detected blood loss was found in 7% and 25%, respectively, of cases of E. histolytica-associated diarrhea. Children who had recovered from a diarrheal episode with E. histolytica, but not E. dispar, had half the chance of developing subsequent E. histolytica-associated diarrhea, consistent with the development of species-specific acquired immunity. In conclusion, the use of modern diagnostic tests demonstrated that E. histolytica contributed to overall morbidity from diarrheal illness. Understanding the etiology, frequency, and consequences of acute diarrhea in children from a developing country should aid in the design of interventions to improve child health.

Entamoeba histolytica infection and colitis occurred in 55% and 4%, respectively, of a cohort of Bangladeshi preschool children observed for 2 years.

Data on sociological and behavioural aspects of malaria, which is essential for an evidence-based design of prevention and control programmes, is lacking in Bangladesh. This paper attempts to fill this knowledge gap by using data from a population-based prevalence survey conducted during July to November 2007, in 13 endemic districts of Bangladesh.