Viral Gastroenteritis

The most common overall cause of acute gastroenteritis globally, predominantly rotavirus (historically the leading cause of severe pediatric diarrheal illness worldwide, now substantially reduced where rotavirus vaccination is implemented) and norovirus (the leading cause of gastroenteritis outbreaks across all ages, notorious for its very low infectious dose, environmental persistence, and rapid spread in closed settings such as cruise ships, hospitals, and care homes), with adenovirus and astrovirus as less common causes.

Acute onset watery diarrhea and vomiting (vomiting often prominent, particularly with norovirus, sometimes the dominant symptom), low-grade fever, and abdominal cramping, generally self-limiting over 1 to 3 days (norovirus) to 5 to 7 days (rotavirus, though can be longer in young children).

Dehydration is the primary risk, particularly in infants and young children (see Severe Dehydration entry).

Usually a clinical diagnosis not requiring specific testing in an otherwise well individual.

Stool viral antigen testing or PCR panels are used where the specific cause matters for infection control purposes (outbreak investigation, hospital/care home settings) or in more severe/atypical presentations warranting broader stool workup.

• Entirely supportive: oral rehydration solution as first line, with escalation to IV fluids for significant dehydration unable to be corrected orally
• Ondansetron (a single dose, weight-based in children) can reduce vomiting and improve the success of oral rehydration, reducing the need for IV fluids and admission in pediatric practice
• No antiviral treatment exists for routine rotavirus or norovirus gastroenteritis
• Zinc supplementation in children under 5 reduces duration and severity
• Infection control is central given high transmissibility, particularly norovirus: strict hand hygiene (note alcohol-based hand sanitizer has reduced efficacy against norovirus, soap and water is preferred), environmental decontamination, and exclusion from work/school/food handling until 48 hours symptom-free
• Prevention: rotavirus vaccine (oral, live attenuated, part of many routine infant immunization schedules) substantially reduces severe rotavirus disease burden

Referral: rarely needed beyond standard gastroenteritis admission criteria for severe dehydration; public health notification for outbreak settings (care homes, hospitals).