What is the treatment for norovirus infection?

Treatment of Norovirus Infection

Norovirus infection has no specific antiviral treatment and management consists entirely of supportive care with oral or intravenous rehydration therapy, as the illness is self-limited in immunocompetent individuals. 1, 2

Primary Treatment Strategy

Fluid Replacement (Cornerstone of Management)

• Oral rehydration therapy is the primary treatment goal for preventing dehydration in norovirus gastroenteritis. 2
• Escalate to intravenous fluid therapy if oral intake is inadequate or signs of severe dehydration are present. 2, 3
• Approximately 10% of patients with norovirus require medical attention, including hospitalization for dehydration management. 3

Symptomatic Management

• Antimotility agents (such as loperamide) may be used in immunocompetent adults with nonbloody diarrhea as part of self-treatment. 2
• For loperamide: initial dose of 4 mg followed by 2 mg after each unformed stool, with a maximum daily dose of 16 mg. 4
• Caution: Avoid antimotility agents in immunocompromised patients or those with bloody diarrhea, as these are not appropriate candidates. 4

Expected Clinical Course

Immunocompetent Patients

• Symptoms begin 12-48 hours after exposure and typically last 12-72 hours with self-resolution. 1, 2, 5
• Longer courses of 4-6 days can occur in young children, elderly persons, and hospitalized patients. 2, 3
• Viral shedding continues for an average of 4 weeks following infection, though infectivity beyond the acute phase is unclear. 2

High-Risk Populations Requiring Heightened Vigilance

• Immunocompromised patients (especially allogeneic stem cell transplant recipients) face mortality rates up to 25% from norovirus gastroenteritis. 1, 5
• These patients are at risk for prolonged infection lasting months to years, with potential for severe malnutrition, villous atrophy, and continuous viral shedding. 5, 6
• Real-time PCR (sensitivity 94%, specificity 92%) should be obtained during the acute phase for diagnosis in immunocompromised patients. 1, 2

Critical Infection Control Measures

Hand Hygiene (Most Important Intervention)

• Handwashing with soap and running water for at least 20 seconds is the most effective method to reduce norovirus contamination. 1, 2, 5
• Alcohol-based hand sanitizers (≥70% ethanol) have limited efficacy against norovirus and should only serve as an adjunct between proper handwashings, never as a substitute. 1, 5

Isolation and Exclusion

• Isolate ill patients in institutional settings until 24-48 hours after complete symptom resolution. 1, 2, 5
• Exclude ill healthcare workers and food handlers from work until 48-72 hours after symptom resolution. 1, 2, 5
• Do not require negative stool results prior to returning to work, as this is not recommended. 1, 3

Environmental Disinfection

• Disinfect contaminated surfaces using sodium hypochlorite (chlorine bleach) solution at 1,000-5,000 ppm (5-25 tablespoons of 5.25% household bleach per gallon of water). 1, 5
• Prepare bleach solutions freshly for use within 2 hours due to evaporative dilution. 1
• Products containing phenolic compounds, triclosan, or quaternary ammonium compounds are less effective against norovirus. 1

When to Escalate Care

Indications for Hospitalization

• Severe dehydration unresponsive to oral rehydration therapy. 3
• Elderly patients or those in long-term care facilities, given the association with mortality in these settings. 3
• Immunocompromised patients with prolonged symptoms or evidence of malnutrition. 1, 5

Red Flags Requiring Immediate Evaluation

• Vomiting or diarrhea persisting for more than one week is atypical and requires immediate evaluation for alternative diagnoses. 2, 3
• Evaluate for other opportunistic pathogens in immunocompromised patients, including Cryptosporidium, Cyclospora, microsporidia, Cystoisospora belli, CMV, and MAC. 2

Common Pitfalls to Avoid

• Do not rely solely on alcohol-based hand sanitizers for infection control, as proper handwashing with soap and water is essential. 3, 5
• Do not assume all cases resolve within 1-3 days, as vulnerable populations frequently have more prolonged courses. 2
• Do not transfer ill patients to unaffected units or facilities except in cases of medical necessity. 1
• Avoid loperamide in pediatric patients less than 2 years of age due to risks of respiratory depression and cardiac adverse reactions. 4