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Risk of diarrhea during the first year of life associated with initial and subsequent colonization by specific
A Cravioto1, R E Reyes, F Trujillo
1Research Department, Instituto Nacional de Ciencias y Tecnología-DIF, Mexico City, Mexico.
Insights
Infant diarrhea in rural Mexico was linked to specific gut pathogens like E. coli and Salmonella. Initial colonization by these enteropathogens offered protection against reinfection during the first year of life.
Area of Science:
- Pediatric Infectious Diseases
- Microbiology
- Epidemiology
Background:
- Diarrheal diseases are a major cause of infant morbidity and mortality globally, particularly in resource-limited settings.
- Understanding the specific enteropathogens causing diarrhea and their impact on colonization resistance is crucial for public health interventions.
Purpose of the Study:
- To investigate the relationship between intestinal colonization by specific enteropathogens and the incidence of diarrhea in rural infants.
- To determine if initial colonization by enteropathogens confers protection against subsequent infections by the same organisms.
Main Methods:
- Longitudinal cohort study of 75 rural infants during their first year of life.
- Fecal cultures collected fortnightly and during diarrheal episodes.
- Identification of enteropathogenic, enterotoxigenic, enteroinvasive, and enterohemorrhagic Escherichia coli, Salmonella sp., Shigella sp., Campylobacter jejuni, and rotavirus using DNA hybridization and culture methods.
- Pathogens isolated within 48 hours prior to diarrhea onset were considered disease-associated.
Main Results:
- High incidence of diarrhea associated with initial isolation of enterohemorrhagic E. coli (82%) and enteropathogenic E. coli or Shigella sp. (64%).
- Lower risk of diarrhea associated with rotavirus (41%) and enterotoxigenic E. coli, Salmonella sp., and C. jejuni (approx. 25%).
- Initial colonization by enteropathogens, regardless of diarrhea association, provided protection against subsequent infections by the same organism.
Conclusions:
- Specific enteropathogens, including E. coli variants and Shigella, are significant causes of diarrhea in this infant population.
- Colonization resistance develops following initial infection, offering protection against reinfection with the same enteropathogen during the first year of life.
- Virulence factors such as Shiga-like toxins and enterotoxins play a role in pathogenicity and the development of protective immunity.
Abstract:
The incidence of colonization by enteropathogenic, enterotoxigenic, enteroinvasive, and enterohemorrhagic Escherichia coli (detected by DNA hybridization with specific radiolabeled probes), Salmonella sp., Shigella sp., Campylobacter jejuni, and rotavirus was related to the presence of diarrhea in a cohort of 75 rural infants followed longitudinally during the first year of life. The study was carried out between August 1985 and February 1987 in the village of Lugar Sobre la Tierra Blanca, in the state of Morelos, 180 km southwest of Mexico City. Intestinal colonization by specific enteropathogens was followed with fecal cultures taken every fortnight and every time a child had diarrhea. Pathogens isolated from cultures taken in the 48 hours prior to the initiation of the diarrheal episode were considered to be associated with the disease. Diarrhea was detected in 82% of the children with initial isolation of enterohemorrhagic E. coli and in 64% of the children with enteropathogenic E. coli or Shigella sp. The risk of diarrhea associated with the initial isolation of other pathogens was lower, at 41% for rotavirus and approximately 25% for enterotoxigenic E. coli, Salmonella sp., and C. jejuni. Initial colonization by the enteropathogens studied, whether or not they were associated with diarrhea, prevented disease, but not colonization by the same organism, when the children were reinfected during the first year of life. Enteropathogenic E. coli adherence factor, human or porcine heat-stable enterotoxins, fimbrial colonization factor antigens, and Shiga-like toxins I and II were important pathogenic characteristics related to the presence of diarrhea and to protection against subsequent infection by the same organisms.