Diarrhea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. Escherichia coli is an emerging agent among pathogens that cause diarrhea. The development of a highly applicable technique for the detection of different categories of diarrheagenic E. coli is important. We have used multiplex PCR by combining eight primer pairs specific for enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC), enterohemorrhagic E. coli, enteropathogenic E. coli (EPEC), and enterotoxigenic E. coli (ETEC). This facilitates the identification of five different categories of diarrheagenic E. coli from stool samples in a single reaction simultaneously. The prevalences of diarrheagenic E. coli were 22.5 and 12% in the diarrhea group and the control group, respectively. Among 587 fecal samples from Vietnamese children under 5 years of age with diarrhea, this technique identified 132 diarrheagenic E. coli strains. This included 68 samples (11.6%) with EAEC, 12 samples (2.0%) with EIEC, 39 samples (6.6%) with EPEC, and 13 samples (2.2%) with ETEC. Among the 249 age-matched controls, 30 samples were positive for diarrheagenic E. coli. The distribution was 18 samples (7.2%) with EAEC, 11 samples (4.4%) with EPEC, and 1 sample (0.4%) with ETEC.

Group A rotavirus, diarrheagenic Escherichia coli, Shigella spp, and enterotoxigenic Bacteroides fragilis play an important role in causing diarrhea in children in Hanoi, Vietnam. Epidemiological factors such as lack of fresh water supply, unhygienic septic tank, low family income, lack of health information, and low educational level of parents could contribute to the morbidity of diarrhea in children.

Group A rotaviruses are the major cause of diarrhea in young children worldwide. From March 2001 to April 2002, 836 children less than 5 years of age were investigated in Hanoi, Vietnam. This included 587 children with diarrhea and 249 age-matched controls. Group A rotavirus was identified in 46.7% of the children with diarrhea and 3.6% of the controls, which was a significant difference. Within the diarrhea group, the highest prevalence was seen in children from 13 to 24 months of age, and the prevalence was higher in males than in females. The symptoms of acute diarrhea caused by rotavirus were watery diarrhea, vomiting, fever, and dehydration. A higher prevalence of rotavirus detection was obtained for children who had all of these symptoms, followed by those who had diarrhea with vomiting-dehydration, fever-dehydration, and dehydration. The high rates occurred from September to December, although the infection was encountered all year round. In 58 patients (21.2% of the rotavirus-infected children), rotavirus infection was detected in association with either diarrheagenic Escherichia coli or Shigella spp. The most frequent combinations were rotavirus-enteroaggregative E. coli and rotavirus-enteropathogenic E. coli. At least one enteropathogen was identified from about 64% percent of the samples. The bacterial infection may not have given rise to clinical symptoms of such severity. The present study demonstrates the burden of rotavirus diarrhea in Hanoi, Vietnam. Continuous surveillance of diarrhea caused by rotavirus in young children would play an important role in diagnosis, treatment, and prophylaxis in order to improve the health of children in Vietnam.

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