Norovirus Symptoms and Management
Primary Symptoms
Norovirus causes acute gastroenteritis with sudden onset of nonbloody diarrhea, vomiting, nausea, and abdominal cramps after a 12-48 hour incubation period. 1, 2
Core Gastrointestinal Manifestations
- Vomiting and diarrhea are the hallmark symptoms, though some patients experience only one or the other 1, 2
- Nausea and abdominal cramps consistently accompany the gastrointestinal symptoms 1, 2
- Diarrhea is characteristically nonbloody and watery 1
Associated Systemic Symptoms
- Low-grade fever and body aches frequently occur, leading to the colloquial term "stomach flu" (though there is no biologic association with influenza) 1, 2
- Additional symptoms may include headache, anorexia, and malaise 3
Clinical Course and Duration
Typical Timeline in Healthy Adults
- Incubation period: 12-48 hours after exposure 1, 2
- Symptom duration: 12-72 hours (1-3 days) with self-resolution in immunocompetent individuals 1, 2, 4
- Symptoms begin with acute, rapid onset once they start 1, 2
High-Risk Populations with Prolonged Course
- Young children, elderly persons, and hospitalized patients can experience prolonged illness lasting 4-6 days 1, 2, 4
- Immunocompromised patients may have chronic diarrhea lasting months to years 2
- Mortality rates up to 25% have been reported in allogeneic stem cell transplant recipients 2, 5
Clinical pitfall: Vomiting or diarrhea persisting beyond one week is atypical and requires immediate evaluation for alternative diagnoses 4, 5
Management Approach
Primary Treatment Strategy
Oral rehydration therapy is the cornerstone of management, with aggressive fluid replacement being the primary treatment goal, as norovirus gastroenteritis is self-limited and requires no specific antiviral therapy. 4, 5
Rehydration Protocol
- Oral rehydration therapy should be initiated immediately to prevent dehydration 4, 5
- Escalate to intravenous fluid therapy if oral intake is inadequate or signs of severe dehydration are present 5
- Approximately 10% of patients require medical attention, including hospitalization for dehydration management 1, 5
Symptomatic Management
- Antimotility agents (e.g., loperamide) may be used in immunocompetent adults with nonbloody diarrhea as part of self-treatment 4, 5
- Treatment is otherwise supportive with fluid and electrolyte substitution 3
Critical Infection Control Measures
Personal Hygiene
- Handwashing with soap and running water for at least 20 seconds is the most effective method to reduce norovirus contamination 4, 5
- Alcohol-based hand sanitizers are NOT effective against norovirus 6
Isolation Requirements
- Isolate ill patients until 24-48 hours after complete symptom resolution in institutional settings (hospitals, long-term care facilities, cruise ships) 4, 5
- Exclude ill healthcare workers, food handlers, and childcare workers from work until 48-72 hours after symptom resolution 4, 5
Critical pitfall: Norovirus requires only 10-100 viral particles to cause infection, making it highly contagious 2. Peak viral shedding occurs 2-5 days after infection with approximately 100 billion viral copies per gram of feces 1, 2, 4. Viral shedding can continue for an average of 4 weeks following infection, though infectivity beyond the acute phase is unclear 1, 2, 4. Up to 30% of infections are asymptomatic, yet these individuals can still shed virus at lower titers 1, 2.
When to Escalate Care
Indications for Hospitalization
- Severe dehydration unresponsive to oral rehydration therapy 5
- Elderly patients or those in long-term care facilities (higher risk of mortality) 1, 5
- Immunocompromised patients with prolonged symptoms or evidence of malnutrition 5
- Symptoms persisting beyond one week warrant evaluation for alternative diagnoses 4, 5