What is norovirus and how is it managed?

From the Guidelines

Norovirus is a highly contagious virus that causes gastroenteritis, and management focuses on supportive care, with the primary goal of reducing morbidity, mortality, and improving quality of life by preventing dehydration and promoting recovery. The virus is characterized by sudden onset of vomiting, watery diarrhea, abdominal cramps, and sometimes low-grade fever. Since there is no specific antiviral treatment, supportive care includes staying hydrated by drinking plenty of fluids like water, clear broths, or oral rehydration solutions such as Pedialyte to replace lost fluids and electrolytes 1. Adults can take over-the-counter medications like loperamide (Imodium) for diarrhea and antiemetics for nausea, though these should be avoided in children without medical advice. Rest is essential, and following the BRAT diet (bananas, rice, applesauce, toast) temporarily while avoiding dairy, fatty, spicy, or sugary foods until recovery can help manage symptoms.

Prevention Strategies

Prevention is crucial as norovirus spreads easily through contaminated food, surfaces, or direct contact with infected individuals. Key prevention strategies include:

• Washing hands thoroughly with soap and water for at least 20 seconds, especially after using the bathroom and before handling food 1.
• Disinfecting contaminated surfaces with a bleach-based cleaner.
• Washing soiled clothing and linens thoroughly.
• Avoiding preparing food for others and staying home from work or school for at least 48 hours after symptoms resolve, as the virus can still be contagious during this period 1.

Outbreak Management

In settings like long-term care facilities, hospitals, and cruise ships, strict control measures including isolation or cohorting of symptomatic patients, exclusion of affected staff, and restricting new admissions into affected units might be required to curtail outbreaks 1. Genotyping of outbreak strains can help identify the source and mode of transmission, guiding effective control measures.

Hand Hygiene

Proper hand washing with soap and running water for at least 20 seconds is the most effective way to reduce norovirus contamination on the hands 1. Hand sanitizers can serve as an adjunct in between proper handwashings but should not be considered a substitute for soap and water handwashing. Additionally, no bare-hand contact with ready-to-eat foods is recommended to prevent transmission.

By prioritizing supportive care, prevention strategies, and proper hand hygiene, individuals can significantly reduce the risk of norovirus transmission and alleviate the symptoms of gastroenteritis, ultimately improving morbidity, mortality, and quality of life outcomes.

From the Research

What is Norovirus

• Norovirus (NoV) is an enteric non-enveloped virus that is the leading cause of gastroenteritis across all age groups 2.
• It is responsible for around 200,000 deaths annually and outbreaks are common in small communities such as educational and care facilities 2.
• Norovirus is transmitted via the faecal-oral route and infection with it results in asymptomatic cases or gastrointestinal disease 2.

Classification and Genotypes

• The classification system available divides NoV into 10 genogroups and 49 genotypes based on whole amino acid sequencing of VP1 capsid protein and partial sequencing of RdRp, respectively 2.
• The most predominant genotypes which cause gastroenteritis in humans include GI.1 and GII.4, where GII.4 is responsible for more extreme clinical implications such as hospitalisation 2.
• GII.4 has been responsible for 6 pandemic strains, the last of which is the GII.4 Sydney (2012) variant 2.

Management and Control

• There are no specific control measures against NoV, therefore common practices are used against it such as hand washing 2.
• No vaccine is available, but the HIL-214 candidate passed clinical phase 2b and shows promise 2.
• Prompt implementation of infection control measures remains the mainstay of norovirus outbreak management 3.
• Infection control strategies and global reporting efforts aimed at controlling this worldwide cause of acute gastroenteritis are crucial 3.

Economic and Social Impact

• It is estimated to cost global economies around £48 billion a year, making it a global issue 2.
• Norovirus outbreaks are common in long-term and acute-care facilities, forming the majority of outbreaks, and nosocomial settings set ideal environments for ease of transmission, especially due to the presence of immunocompromised groups 2.