What is the primary cause of infectious diarrhea in a child under 5 years old, often characterized by vomiting and dehydration?

The primary cause of infectious diarrhea in children under 5 years old, particularly associated with symptoms like vomiting and dehydration, is indeed rotavirus. This virus is known for causing severe gastroenteritis in young children, which can lead to significant fluid loss and the potential for dehydration, a serious condition in this age group.

Rotavirus is highly contagious and spreads easily among children, especially in childcare settings. It typically presents with acute onset of vomiting and watery diarrhea, which can quickly deplete the child’s fluid and electrolyte levels. The introduction of the rotavirus vaccine has significantly decreased the incidence and severity of rotavirus infections, but it remains a leading cause of diarrhea-related hospitalizations in young children.

Other options listed, such as norovirus, salmonella, and Escherichia coli, can also cause diarrhea but are not the predominant pathogens in the specific age group mentioned. Norovirus, while common, often affects older children and adults, and the other two, salmonella and E. coli, typically result from contaminated food sources and are less frequently the primary cause of diarrhea in toddlers. Understanding the role of rotavirus in pediatric infectious diarrhea helps emphasize the importance of vaccination and preventative measures in early childhood health.