What is Norovirus?

From the Guidelines

Norovirus infection should be managed primarily through supportive care, focusing on preventing dehydration, and prevention measures such as thorough handwashing with soap and water for at least 20 seconds, as emphasized in the updated guidelines 1. The virus causes gastroenteritis, characterized by sudden onset of vomiting, watery diarrhea, abdominal cramps, and sometimes low-grade fever.

• Treatment is primarily supportive, focusing on preventing dehydration through oral rehydration solutions like Pedialyte or homemade solutions (1 teaspoon salt, 8 teaspoons sugar in 1 liter of water) 1.
• Adults should drink at least 2-3 liters of fluids daily while ill, and children should take small, frequent sips.
• Over-the-counter medications like loperamide (Imodium) can help control diarrhea in adults but should be avoided in children.
• Anti-nausea medications such as ondansetron may be prescribed in severe cases. Most people recover within 1-3 days without specific treatment. Prevention is crucial as norovirus spreads easily through contaminated food, surfaces, or direct contact with infected individuals.
• Thorough handwashing with soap and water for at least 20 seconds is essential, as alcohol-based sanitizers are less effective against norovirus 1.
• Infected individuals should avoid preparing food for others for at least 48 hours after symptoms resolve and should stay home from work or school until symptom-free for 24-48 hours to prevent spreading the infection 1. Norovirus is a major cause of foodborne illness, responsible for at least 50% of all gastroenteritis outbreaks worldwide, with approximately 21 million illnesses attributable to norovirus estimated to occur annually in the United States 1.

From the Research

Norovirus Transmission and Prevention

• Norovirus can spread through multiple transmission routes, including person-to-person and foodborne, with the faecal-oral route being the primary mode of transmission 2.
• The virus has a low infectious dose, high shedding titre, and environmental stability, making it difficult to prevent and control 3.
• Prevention and control guidelines focus on principles of disinfection and decontamination, including hand hygiene, limiting exposure to infectious individuals, and thorough environmental decontamination 3, 4.

Norovirus Treatment and Management

• There are no specific antiviral treatments available for norovirus infections, but clinical trials are underway to evaluate the efficacy of vaccines 5, 6.
• Treatment for norovirus infections is primarily focused on managing symptoms, such as dehydration and electrolyte imbalance, through oral rehydration therapy or intravenous fluid therapy 6.
• Judicious use of ondansetron can increase the success rate of oral rehydration therapy and minimize the need for intravenous therapy and hospitalization 6.

Norovirus Epidemiology and Virology

• Norovirus is the leading cause of gastroenteritis across all age groups, responsible for around 200,000 deaths annually and outbreaks are common in small communities such as educational and care facilities 2.
• The virus has high mutational rates, allowing for new variants to emerge and be more resistant, with the most predominant genotypes including GI.1 and GII.4 2.
• The classification system divides norovirus into 10 genogroups and 49 genotypes based on whole amino acid sequencing of VP1 capsid protein and partial sequencing of RdRp, respectively 2.