What is the treatment for norovirus-induced diarrhea?

Treatment of Norovirus-Induced Diarrhea

Norovirus gastroenteritis is self-limited and requires no specific antiviral therapy—treatment focuses exclusively on aggressive oral rehydration to prevent dehydration, which is the primary treatment goal. 1

Immediate Rehydration Strategy

Oral rehydration solution (ORS) is the cornerstone of treatment and should be started immediately. 2 The most effective formulation contains 65-70 mEq/L sodium and 75-90 mmol/L glucose for mild to moderate dehydration. 2

• Target 2200-4000 mL/day total fluid intake, with administration rate exceeding ongoing losses 2
• Continue ORS until clinical dehydration is corrected and diarrhea resolves 2
• For mild illness, diluted fruit juices, flavored soft drinks with saltine crackers, and broths can supplement, though commercial ORS is superior 2
• Oral rehydration therapy is as effective as intravenous fluid therapy for children with mild-to-moderate dehydration 3

Common pitfall: Gatorade may cause persistent hypokalemia and should not be the primary rehydration solution, though it can supplement ORS. 4

Symptomatic Management

Loperamide may be used cautiously in immunocompetent adults with nonbloody diarrhea. 1, 2

• Dosing: 4 mg initially, then 2 mg every 2-4 hours or after each unformed stool, maximum 16 mg daily 2
• Absolute contraindication: Do not use if fever or bloody stools are present due to risk of toxic megacolon 2
• In children, ondansetron can increase success rate of oral rehydration therapy and minimize need for IV therapy 3

Expected Clinical Course

Understanding the natural history helps avoid unnecessary interventions:

• Incubation period: 12-48 hours after exposure 2
• Symptom duration in healthy individuals: typically 12-72 hours with self-resolution 1
• Prolonged courses of 4-6 days can occur in young children, elderly persons, and hospitalized patients 1
• Peak viral shedding occurs 2-5 days after infection, with shedding continuing for average of 4 weeks 1, 2

Red flag: Vomiting or diarrhea persisting beyond 7 days is atypical and requires evaluation for alternative diagnoses. 1, 2

Isolation and Infection Control

These measures are critical to prevent transmission:

• Isolate ill patients until 24-48 hours after complete symptom resolution in institutional settings (hospitals, long-term care facilities, cruise ships) 1, 2, 5
• Exclude ill healthcare workers, food handlers, and childcare workers until 48-72 hours after symptom resolution 1, 2, 5
• Handwashing with soap and running water for minimum 20 seconds is the most effective method to reduce norovirus contamination 6, 1, 2, 5
• Alcohol-based hand sanitizers (≥70% ethanol) can be used as an adjunct between proper handwashings but should NOT substitute for soap and water 6, 5
• Disinfect environmental surfaces with chlorine bleach solution (1,000-5,000 ppm) or EPA-approved disinfectants, focusing on bathrooms and high-touch surfaces 6, 5

Critical caveat: Alcohol-based sanitizers have limited efficacy against norovirus—soap and water handwashing is non-negotiable. 5, 7

Special Population Considerations

Immunocompromised patients require additional evaluation:

• Obtain stool specimens during acute phase for RT-qPCR diagnosis 1, 2
• Evaluate for other opportunistic pathogens including Cryptosporidium, Cyclospora, microsporidia, Cystoisospora belli, CMV, and MAC, particularly in HIV-infected patients 1

Elderly patients (especially over 90 years in long-term care facilities) warrant close monitoring due to increased risk of death and hospitalization during outbreaks. 2

Children may benefit from ondansetron to facilitate oral rehydration and prevent hospitalization. 3

When to Pursue Diagnostic Testing

• In outbreak settings: collect whole stool specimens from at least five persons during acute illness (≤72 hours from onset) for RT-qPCR diagnosis and genotyping 6, 1, 2
• For immunocompromised patients with suspected norovirus 2
• When symptoms persist beyond 7 days to evaluate for alternative diagnoses 2

Do not require negative stool results prior to returning to work—this is unnecessary and delays appropriate return. 5