What are the symptoms and management of norovirus infection?

Norovirus Symptoms and Management

Norovirus infection presents with acute onset of vomiting, nonbloody diarrhea, nausea, and abdominal cramps after a 12-48 hour incubation period, with symptoms typically resolving in 1-3 days in healthy individuals through supportive care alone. 1

Clinical Presentation

Primary Symptoms

• Vomiting and diarrhea are the hallmark features, though some patients may experience only one or the other 1
• Nausea and abdominal cramps accompany the gastrointestinal symptoms 1
• Low-grade fever and body aches may occur, leading to the colloquial term "stomach flu" (though unrelated to influenza) 1
• Rapid onset characterizes the illness, with abundant vomiting or diarrhea developing suddenly 2

Incubation and Duration

• Incubation period: 12-48 hours after exposure 1
• Symptom duration: 12-72 hours in immunocompetent hosts 1
• Typical resolution: 1-3 days in otherwise healthy persons without treatment 1
• Prolonged illness (4-6 days) can occur in young children, elderly persons, and hospitalized patients 1

High-Risk Populations Requiring Vigilance

Vulnerable Groups

• Elderly patients in long-term care facilities face increased mortality risk, with deaths reported in outbreak settings 1
• Immunocompromised patients (particularly allogeneic stem cell transplant recipients) can experience mortality rates up to 25% 1
• Cancer patients with impaired cellular immunity may develop prolonged courses lasting years with chronic diarrhea and continuous viral shedding 1, 3

Management Approach

Supportive Care (Primary Treatment)

• Oral rehydration therapy is the mainstay of treatment for most patients 1
• Intravenous fluid therapy for patients requiring hospitalization (approximately 10% seek medical attention) 1
• No specific antiviral treatment is currently available for norovirus 1

Special Considerations for Immunocompromised Patients

While no definitive treatment exists, several strategies have been attempted in case reports for prolonged infection in immunocompromised patients, though with varying results: nitazoxanide, ribavirin, and enterally administered immunoglobulin 3. However, these remain investigational and lack robust evidence.

Infection Control Principles

Transmission Characteristics

• Highly contagious: only 10-100 viral particles required for infection 1
• Multiple transmission routes: person-to-person contact, contaminated food/water, aerosols from vomitus 1, 4
• Prolonged viral shedding: average 4 weeks in stool, with peak shedding 2-5 days after infection 1
• Asymptomatic transmission: up to 30% of infections are asymptomatic, yet these individuals can still shed virus 1

Critical Infection Control Measures

• Hand hygiene with soap and water (alcohol-based sanitizers are insufficient) 5
• Environmental decontamination with EPA-registered disinfectants effective against norovirus 1
• Isolation of infected patients: separate bathroom facilities and no new admissions to affected rooms 2
• Contact precautions for healthcare workers and exposed individuals 4

Key Clinical Pitfalls

Avoid alcohol-based hand sanitizers alone—norovirus is resistant to alcohol, requiring soap and water for effective hand hygiene 5.

Do not dismiss prolonged symptoms in immunocompromised patients—what appears as typical norovirus in healthy individuals can become chronic infection with severe malnutrition, dehydration, and electrolyte imbalance in those with impaired immunity 1, 3.

Remember the diarrhea is nonbloody—bloody diarrhea should prompt consideration of alternative diagnoses 1.