Enteropathogen infection and household factors associated with linear child growth in Bangladesh

Abstract

BACKGROUND: The dual burden of enteropathogen infection and childhood malnutrition continues to be a global health concern and a leading cause of morbidity and death among children. Despite improvements in recent decades, Bangladesh continues to be one of the countries with the highest burden of growth impairment. In addition, enteropathogen infection continues to be highly prevalent in the country. An understanding of factors associated with infection and growth could contribute to public health efforts to reduce this burden through targeted community interventions. This PhD thesis aimed to examine the association between household factors and enteropathogen infection and linear child growth in Bangladesh using both national surveys and study-specific data. METHODS: The association of household-level factors with childhood growth, as measured by length-for-age z-score (LAZ), were first analysed using data of children 1-24 months of age from two cross-sectional national surveys in Bangladesh: the 2014 Demographic and Health Survey (DHS), and the 2012-2013 Multiple Indicator Cluster Survey (MICS). Both analyses were age-stratified (1-12 months and 13-24 months), and then further stratified into rural vs urban households to identify heterogeneity in associations of factors with LAZ by age and location. An analysis of longitudinal data was then carried out of children participating in the Etiology, Risk Factors, and Interaction of Enteric Infections and Malnutrition and Consequences for Child Health (MAL-ED) Study in Mirpur, Bangladesh. Latent growth curve modelling (LGCM), a form of longitudinal modelling technique, was applied to this data to evaluate the trajectories of change in LAZ and explore the effect of enteropathogen infection and household-level factors on this growth trajectory.RESULTS: In all three analyses, an inverse association was found between increasing age and LAZ, consistent with previous research. In the DHS and MICS survey data, older children (13-24 months) had more household factors associated with LAZ. Maternal education was positively associated with linear growth in both national-level datasets, as were improved toilet facilities. In the MICS analysis, rural households had more factors associated with LAZ. Male sex, dirt flooring material, and unimproved toilet facility, and animal ownership were negatively associated with LAZ, while refrigerator ownership and increased maternal education were positively associated. In rural households in the DHS analysis, an episode of diarrhea in the preceding two weeks, a shared toilet facility and no maternal education were negatively associated with LAZ. In the LGCM analysis of children from the MAL-ED Bangladesh site, Campylobacter infection was highly prevalent and had an effect on growth at specific age intervals. Infection in the preceding 3-month interval was negatively associated with LAZ between 12 and 18 months of age; similarly, infection in the preceding 6-month interval was negatively associated with LAZ at between 15 and 21 months of age. Maternal height and birth order were positively associated with LAZ at birth but were not associated with infection. Duration of antibiotic use and treated drinking water were negatively associated with Campylobacter infection, with the strength of the latter effect increasing with children’s age.CONCLUSION: The results indicate that growth impairment continues to be a public health concern in Bangladesh, and that child growth is associated with enteropathogen infection and household-level factors that may serve as pathogen household reservoirs. Different household factors are associated with growth in children according to different age groups and their geographical location (urban versus rural), with older rural children having the most factors associated with growth. Enteropathogen infection, particularly Campylobacter, was found to have a negative effect on linear growth, with this effect being greatest at specific age intervals in the second year of life. The results of these analyses taken together highlight the need for public health interventions to target household factors involved in enteric pathogen transmission at specific ages of children and specific geographic locations.