What are the signs and symptoms of viral gastroenteritis?

Signs and Symptoms of Viral Gastroenteritis

Viral gastroenteritis presents with a characteristic triad of vomiting, non-bloody diarrhea, and abdominal cramps, with the key distinguishing feature being the absence of blood in the stool. 1

Core Gastrointestinal Symptoms

The primary manifestations include:

• Nausea occurs in approximately 79% of cases and is particularly prominent in Norwalk-like virus infections 1
• Vomiting affects 69% of patients overall, occurring in 80-90% of infected children with rotavirus (though typically brief, lasting ≤24 hours), while a higher proportion of children experience vomiting compared to adults 1, 2
• Non-bloody diarrhea presents in 66% of cases and is relatively more prevalent among adults, with children typically having 10-20 bowel movements per day during acute illness 1, 2
• Abdominal cramps and pain occur in 71% of affected individuals 1, 3

Constitutional Symptoms

Beyond gastrointestinal manifestations, patients commonly experience:

• Fever develops in 37-50% of cases, usually low-grade (generally ≤38.5°C) 1, 2, 4
• Headache affects approximately 50% of patients 1
• Chills occur in 32% of cases 1
• Myalgias present in 25-50% of affected persons 1
• Sore throat is reported in 18% of cases 1

Temporal Characteristics

The clinical timeline varies by viral pathogen:

• Incubation period: 12-48 hours for norovirus; 24-36 hours for astrovirus; 1-3 days for rotavirus 1, 2
• Duration of illness: 12-72 hours for norovirus in immunocompetent hosts; 1-4 days for astrovirus; 3-8 days for rotavirus 1, 2
• Vomiting duration: Typically resolves within 24 hours or less, particularly with rotavirus 2, 5

Age-Specific Presentations

Children demonstrate distinct patterns:

• Vomiting is more prominent, occurring in up to 90% of pediatric cases 2
• Rotavirus disease is most severe in children aged 3-24 months 2
• Higher frequency of bowel movements (10-20 per day) during acute phase 2

Adults typically experience:

• Diarrhea relatively more prevalent than in children 1
• Nausea is particularly prominent 1
• Average illness duration of 12-60 hours 1, 2
• May experience persistence of constitutional symptoms for several weeks, especially in elderly patients 1

Critical Distinguishing Features

Key characteristics that identify viral etiology:

• Absence of blood in stool is present in >90% of viral gastroenteritis cases, distinguishing it from bacterial causes 1, 4
• Absence of white blood cells in stool differentiates viral from bacterial infections (except CMV) 4
• Self-limited course with most cases resolving within one week 1, 5

Warning Signs Requiring Medical Attention

Seek immediate evaluation for:

• Severe dehydration signs: inability to maintain oral hydration, decreased urine output, altered mental status 2, 6
• Bloody diarrhea suggests bacterial or other non-viral etiology requiring stool testing 6, 5
• Symptoms persisting beyond 7 days warrant consideration of bacterial, parasitic, or non-infectious causes 6, 5
• Electrolyte imbalance complications, which have caused deaths in adults during Norwalk-like virus illness 1

Special Population Considerations

Immunocompromised patients may present with:

• Prolonged courses of diarrhea lasting weeks 2, 5
• Extended viral shedding periods 2
• Mortality rates up to 25% in allogeneic stem cell transplant patients with norovirus 2

Elderly patients experience:

• More severe symptoms due to waning immunity 1, 2
• Prolonged constitutional symptoms lasting several weeks 1
• Higher risk of complications from dehydration, especially those on diuretics 2

Post-Illness Sequelae

• Mild lactose intolerance may persist for 10-14 days after infection 2, 6
• Post-infectious irritable bowel syndrome develops in approximately 9-10% of patients 6