What is the management of norovirus infections?

Management of Norovirus Infections

The primary treatment for norovirus gastroenteritis is aggressive oral rehydration therapy to prevent dehydration, with escalation to intravenous fluids when oral intake is inadequate, as there is no specific antiviral therapy available. 1, 2

Immediate Clinical Management

Hydration is the cornerstone of treatment:

• Oral rehydration therapy should be initiated immediately for all patients with norovirus gastroenteritis 1, 2
• Escalate to intravenous fluid therapy if oral intake is inadequate or signs of severe dehydration develop 1
• Approximately 10% of norovirus patients require medical attention, including hospitalization for dehydration management 3, 1

Symptomatic management options:

• Antimotility agents (such as loperamide) may be used in immunocompetent adults with nonbloody diarrhea 1, 2
• Antiemetics are commonly used, with 33% of norovirus-positive episodes receiving antiemetic therapy 4

Expected Clinical Course

Typical timeline in immunocompetent patients:

• Symptoms begin 12-48 hours after exposure with acute onset 1, 2
• Illness typically lasts 12-72 hours with self-resolution 1, 2
• Peak viral shedding occurs 2-5 days after infection, with viral shedding continuing for an average of 4 weeks 3, 2

Important caveat: Young children, elderly patients, and hospitalized individuals frequently have more prolonged courses lasting 4-6 days 2. Vomiting or diarrhea persisting beyond one week is atypical and requires immediate evaluation for alternative diagnoses 1, 2.

Critical Infection Control Measures

Hand hygiene is paramount:

• Handwashing with soap and running water for at least 20 seconds is the most effective method to reduce norovirus contamination 3, 1, 2, 5
• Alcohol-based hand sanitizers (≥70% ethanol) can be used as an adjunct between proper handwashings but should NOT be considered a substitute for soap and water 3, 5
• This is critical because norovirus is a non-enveloped virus with limited susceptibility to alcohol-based sanitizers 3, 5

Isolation and exclusion protocols:

• Isolate ill patients in institutional settings (hospitals, long-term care facilities, cruise ships) until 24-48 hours after complete symptom resolution 3, 1, 2, 5
• Exclude ill healthcare workers, food handlers, and childcare workers from work until 48-72 hours after symptom resolution 3, 1, 2, 5
• Do NOT require negative stool results prior to returning to work 3, 5
• In licensed food establishments, regulatory authority approval may be necessary before reinstating excluded food employees 3

Environmental disinfection:

• After initial cleaning to remove soiling, disinfect contaminated surfaces using chlorine bleach solution at 1,000-5,000 ppm (1:50 to 1:10 dilution of household bleach) or EPA-approved disinfectants 3, 5
• Pay particular attention to bathrooms and high-touch surfaces such as door knobs and hand rails 5
• In healthcare settings, use EPA-registered products with label claims for healthcare use, following manufacturer's instructions for dilution, application, and contact time 3

Special Population Considerations

Immunocompromised patients require heightened vigilance:

• Immunocompromised patients, especially allogeneic stem cell transplant recipients, face mortality rates up to 25% from norovirus gastroenteritis 1
• Obtain stool specimens during the acute phase for RT-qPCR diagnosis, as this is the most reliable diagnostic method 2
• Evaluate for other opportunistic pathogens including Cryptosporidium, Cyclospora, microsporidia, Cystoisospora belli, CMV, and MAC, particularly in HIV-infected patients 2

Elderly and long-term care facility residents:

• These populations are at higher risk for severe outcomes and norovirus-associated deaths 3
• During outbreaks in long-term care facilities, consider isolating both exposed and unexposed well persons to break the cycle of transmission 3, 5

When to Escalate Care

Hospitalization is indicated for:

• Severe dehydration unresponsive to oral rehydration therapy 1
• Elderly patients or those in long-term care facilities with significant symptoms 1
• Immunocompromised patients with prolonged symptoms or evidence of malnutrition 1
• Symptoms persisting beyond one week, which warrants immediate evaluation for alternative diagnoses 1, 2

Outbreak Management

Prompt investigation and reporting:

• Initiate investigations immediately, collecting clinical and epidemiologic information to identify the predominant transmission mode and possible source 3, 2, 5
• Collect whole stool specimens from at least five persons during the acute phase of illness (≤72 hours from onset) for RT-qPCR diagnosis 3, 2, 5
• Perform genotyping on norovirus-positive specimens and report results to CDC via CaliciNet 3, 2
• Report all outbreaks to state and local health departments and to CDC via the National Outbreak Reporting System 3, 5

Additional outbreak control measures:

• Eliminate bare-hand contact with ready-to-eat foods 3, 5
• Cohort ill patients together with dedicated nursing staff in healthcare facilities 3, 5
• Do not transfer ill patients to unaffected units except for medical necessity and after consultation with infection control 3
• Minimize risk of spread by not transferring or allowing incubating/asymptomatically infected patients and staff to work in unaffected areas, typically for 48 hours after exposure 3, 5

Common Pitfalls to Avoid

• Do not rely on alcohol-based hand sanitizers alone – they have limited efficacy against norovirus and must not replace soap and water handwashing 3, 5
• Do not use empiric antibiotics – only 7% of norovirus-positive episodes appropriately received antibiotics (likely for suspected bacterial co-infection), compared to inappropriate use in 14% of norovirus-negative episodes 4
• Do not assume all cases resolve in 1-3 days – vulnerable populations frequently have prolonged courses 2
• Do not require negative stool testing before return to work – this is not recommended and impractical given prolonged viral shedding 3, 5