PhD Exit Seminar: Infection, malnutrition and household environments: Investigating child malnutrition risk in Timor-Leste through a One Health lens

Abstract

Childhood diarrhoea and severe acute malnutrition (SAM) remain major causes of morbidity and mortality among children under five years in low- and middle-income countries (LMICs), yet it remains unclear why only some children exposed to similar environmental and infectious risks progress to severe illness requiring hospitalisation.

This thesis investigated why some children progress to hospitalisation for SAM while others do not use a One Health approach integrating biological, environmental, and social dimensions of risk. Study 1 used a systematic review and meta-analysis to quantify the contribution of major bacterial enteropathogens to childhood diarrhoea in LMICs. Study 2 employed a matched case–control design in Timor-Leste to identify socio-economic, environmental, feeding, and microbial factors associated with hospitalisation for SAM using Directed Acyclic Graph-guided conditional logistic regression. Study 3 used qualitative in-depth interviews with caregivers to examine how household food practices, caregiving responsibilities, food allocation, and economic constraints shape child nutrition and food security. Study 4 used qualitative in-depth interviews to explore household food and water safety practices, contamination pathways, and adaptive responses to environmental and infrastructural constraints.

Study 1 found that diarrhoeagenic E. coli (23.0%), Shigella spp. (8.8%), andCampylobacter spp. (8.6%) were the most frequently detected bacterial enteropathogens associated with childhood diarrhoea in LMICs. Study 2 identified maternal non-completion of formal education, short birth spacing, unimproved drinking water, absence of breastfeeding, missed vaccination, rotavirus infection, and household food insecurity as key factors associated with hospitalisation for SAM, while pathogen exposure was similarly common among cases and controls. Study 3 showed that household food practices were shaped by women’s caregiving authority, adaptive food allocation, food sharing obligations, economic precarity, and intergenerational knowledge transfer. Study 4 demonstrated that households actively adapted food preparation, storage, water management, and hygiene practices in response to environmental contamination, seasonal variability, and infrastructural limitations, but these adaptations were constrained by broader structural conditions.

Together, these findings indicate that hospitalisation for SAM is best understood as the result of cumulative vulnerability arising from the interaction of microbial exposure, environmental conditions, food insecurity, caregiving systems, and structural disadvantage rather than any single risk factor. This thesis advances a One Health cumulative exposure–vulnerability perspective and supports integrated approaches to nutrition, infection prevention, environmental health, and household resilience in resource-constrained settings.

Speaker

Md Abu Sayeed is a Veterinarian and Epidemiologist and a PhD candidate at the National Centre for Epidemiology and Population Health (NCEPH), the Australian National University. His doctoral research focuses on understanding why some children progress from common pathogen exposure to severe outcomes such as hospitalisation with severe acute malnutrition (SAM) by integrating biological, environmental, and household determinants. Prior to commencing his doctoral studies, he worked as a Research Officer (Epidemiology) at the Institute of Epidemiology, Disease Control and Research (IEDCR), Bangladesh, where he contributed to national disease surveillance and zoonotic research programmes. His research applies a One Health approach to examine how infections, environments, and household systems interact to shape child health and inform evidence-based public health policy and practice.