The epidemiology and aetiology of diarrhoeal disease in infancy in southern Vietnam: a birth cohort study

Abstract

Objectives: Previous studies indicate a high burden of diarrhoeal disease in Vietnamese children, however longitudinal community-based data on burden and aetiology are limited. The findings from a large, prospective cohort study of diarrhoeal disease in infants in southern Vietnam are presented herein.

Methods: Infants were enrolled at birth in urban Ho Chi Minh City and a semi-rural district in southern Vietnam, and followed for 12 months (n=6706). Diarrhoeal illness episodes were identified through clinic-based passive surveillance, hospital admissions, and self-reports.

Results: The minimum incidence of diarrhoeal illness in the first year of life was 271/1000 infant-years of observation for the whole cohort. Rotavirus was the most commonly detected pathogen (50% of positive samples), followed by norovirus (24%), Campylobacter (20%), Salmonella (18%), and Shigella (16%). Repeat infections were identified in 9% of infants infected with rotavirus, norovirus, Shigella, or Campylobacter, and 13% of those with Salmonella infections.

Conclusions: The minimum incidence of diarrhoeal disease in infants in both urban and semi-rural settings in southern Vietnam was quantified prospectively. A large proportion of laboratory-diagnosed disease was caused by rotavirus and norovirus. These data highlight the unmet need for a rotavirus vaccine in Vietnam and provide evidence of the previously unrecognized burden of norovirus in infants.

Keywords: Cohort study; Diarrhoeal disease; Epidemiology; Infants; Infectious diarrhoea; Rotavirus.

Figure 1

Aetiology of diarrhoeal disease. The proportion of diarrhoeal episodes (among those with a positive stool sample) that were positive for each single pathogen or combination of pathogens, (A) by study site, and (B) by hospitalization status.

Figure 2

Time interval between repeated infections with enteric pathogens. Each box-and-whiskers plot shows the distribution of time intervals (in days) between repeated infections with the same enteric pathogen. Boxes indicate the median and interquartile range, and the whiskers indicate the 5^th and 95^th percentiles. RoV, rotavirus; NoV, norovirus; Shig, Shigella; Campy, Campylobacter; Salm, Salmonella. The numbers below each pathogen label indicate the total number of secondary or tertiary infections for that pathogen.

Figure 3

Spatial clustering of diarrhoeal cases in Dong Thap Province. (A) Vietnam is shown in grey, with Ho Chi Minh City (HCMC) indicated with the black cross and Dong Thap indicated with the red cross. (B) Location of Dong Thap Province, with the hospital indicated by the red cross. (C) Locations of households with diarrhoea shown with coloured points, as follows: blue, rotavirus; green, norovirus; red, Shigella; orange, Salmonella; purple, Campylobacter. Grey points show the locations of the households of children in the cohort for whom diarrhoea was not reported during the period of follow-up. Shaded circles indicate the location of the significant clusters, with colours corresponding to the individual pathogens listed above. The red cross shows the location of Dong Thap Provincial Hospital. Grey borders show the borders of Cao Lanh district (large border) and Cao Lanh town (small, embedded border). Actual household locations have been jittered for display on the map.