Most Common Cause of Diarrhea in Children Under 18 Years
Rotavirus is the most common cause of acute diarrhea in children under 18 years of age, accounting for approximately 25% of all diarrheal episodes and responsible for 30-50% of hospitalizations for diarrhea in children under 5 years. 1
Epidemiologic Evidence
The evidence consistently demonstrates rotavirus as the leading pathogen across multiple guidelines and surveillance systems:
Rotavirus causes the highest burden of severe diarrheal disease, with virtually all children becoming infected in the first 3-5 years of life, though severe diarrhea and dehydration occur primarily in children aged 3-35 months 1
In the United States, rotavirus is responsible for one-fourth (25%) of all acute diarrhea cases in children, but accounts for a disproportionately higher percentage of severe cases requiring medical intervention 1
Before rotavirus vaccine introduction, rotavirus caused approximately 3 million annual episodes of acute gastroenteritis, over 500,000 physician visits, and 50,000 hospitalizations among children under 5 years in the United States 1
The cumulative lifetime risk is substantial: 4 out of 5 children (80%) will develop rotavirus diarrhea in the first 5 years of life, with 1 in 7 requiring a clinic or emergency room visit and 1 in 78 requiring hospitalization 1
Age-Specific Patterns
The disease burden varies significantly by age:
Peak incidence occurs between 6 months and 2 years of age, with 72% of rotavirus hospitalizations occurring in the first 2 years of life and 90% by age 3 years 1
Neonates are relatively protected by transplacental maternal antibodies, though preterm infants remain at higher risk due to lack of these protective antibodies 1
First infections are most severe, with subsequent infections typically being milder or asymptomatic due to development of protective immunity 1
Other Important Pathogens
While rotavirus predominates, other pathogens contribute to the overall burden:
Norovirus has become increasingly important, particularly after widespread rotavirus vaccination, and is now the leading cause among vaccinated populations 1
Bacterial pathogens include Salmonella (most common bacterial cause), Campylobacter, Shigella, Yersinia, and certain E. coli strains, collectively accounting for a smaller proportion of cases but important for severe or bloody diarrhea 1
Parasitic causes such as Giardia, Cryptosporidium, and Entamoeba histolytica are less common but clinically significant 1
Clinical Implications
Understanding rotavirus as the predominant cause has important management implications:
Most acute diarrhea in previously healthy children is viral and self-limited, making routine laboratory testing unnecessary in typical cases 1
The seasonal pattern (November to May in the United States, spreading from Southwest to Northeast) can aid clinical suspicion 1
Oral rehydration therapy remains the cornerstone of treatment regardless of etiology, as the mainstay of management is appropriate fluid and electrolyte therapy rather than pathogen-specific treatment 1