Diarrhoeal disease in children under the age of five in Ho Chi Minh City, Vietnam

Thesis

The focus of the global diarrhoeal disease burden is in low and middle-income countries, where the disease epidemiology and aetiology is highly variable and not well characterised. The aim of this thesis was to challenge the knowledge gaps regarding diarrhoeal disease in children under the age of five in Ho Chi Minh City (HCMC), Vietnam.

Firstly, a pilot surveillance in southern Vietnam demonstrated a preponderance of enteric viruses in hospitalised diarrhoeal children and reported the first rotavirus G12 in Vietnam; despite being geographically disproportional distributed, rotavirus (RoV) predominated followed by norovirus (NoV). On the basis of these data, a prospective multi-centre hospitalbased surveillance was conducted in HCMC to study diarrhoeal disease in detail and investigate the extent and the epidemiology of the hypothesized NoV emergence. Faecal specimens from diarrhoea patients and diarrhoea-free children were screened for a panel of pathogens; RoV was again identified as the predominant agent, followed by NoV. Enteric bacteria were found at smaller proportions, and exhibited excessive antimicrobial resistance. As NoV was found to be highly endemic and a major cause of hospitalisation, a risk factor analysis for NoV infections was performed. Risk factors included young age, residential crowding and contact with symptomatic individuals. Additional analysis on the phylogenetic structure of NoV strains demonstrated diverse genotypes circulating, most commonly belonging to the GII.4 lineage. A spatiotemporal analysis of GII.4 variants, GII.4-2006b (Minerva) and the novel emergent GII.4-2010 (New Orleans), suggested a strain replacement phenomenon and detected a cluster of GII.4-2010 in the northeastern part of the city. These studies indicate prominent disease dynamics involved rapid evolution of viruses, necessitate studies on strain distribution and genomic analyses and potential source additionally contributing to genetic variations (animal reservoirs), and suggest considerable impact of RoV and NoV immunisation in Vietnam.

Authors: Phan, V; Vu Tra My Phan

• Publication date: 2013
• DOI: 10.5287/ora-bpndxxb8k
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: risk factors; genotypes; children; Ho Chi Minh City; diarrhoea; phylogenetics; Salmonella; rotavirus; Shigella; norovirus; Campylobacter; spatio-temporal; Vietnam
• Subjects: Infectious diseases; Genetics (medical sciences); Clinical microbiology; Viruses; Paediatrics; Tropical medicine; Gastroenterology; Epidemiology