As norovirus cases surge across the US, understanding this highly contagious virus is crucial to prevent its spread and protect our communities.
At a Glance
- Norovirus, a leading cause of gastroenteritis, spreads easily through contaminated food, water, and surfaces.
- Symptoms include vomiting, diarrhea, and abdominal pain, appearing 12-24 hours post-exposure.
- No specific treatment exists; management focuses on rehydration and symptom relief.
- Preventive strategies emphasize good hygiene, safe food handling, and cleaning with bleach-based products.
Impact and Transmission of Norovirus
Norovirus, often called “winter vomiting bug,” is a major cause of viral gastroenteritis globally. Responsible for approximately 18% of gastroenteritis cases and around 200,000 deaths annually, it is highly contagious and spreads through contaminated surfaces, food, water, and close contact with infected individuals. Notably, in the U.S., it leads to 19-21 million illnesses yearly, positioning it as the top cause of foodborne disease outbreaks. Concerningly, the virus is rampant, particularly in confined spaces such as cruise ships and dormitories.
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A new strain, GII.17, has recently emerged, exacerbating the current surge due to lower population immunity. Outbreaks have increased from 69 to 91 as of early December. Foods like ready-to-eat cold foods and raw shellfish, especially oysters, pose a high risk for contamination. Alcohol-based hand sanitizers fall short against norovirus, but thorough handwashing with soap and water is effective.
Symptoms and Diagnosis
Norovirus symptoms manifest between 12 to 24 hours after exposure, typically causing acute vomiting, non-bloody diarrhea, abdominal cramps, nausea, and occasionally low-grade fever. Diagnosing norovirus often relies on these symptoms, but RT-qPCR remains the most reliable laboratory test. Despite the severity of these symptoms, most individuals recover within about three days, provided they maintain adequate hydration and manage symptoms appropriately.
Effective management involves rehydration through oral rehydration solutions or intravenous fluids to prevent dehydration. Over-the-counter anti-diarrheal and anti-nausea medications may be recommended. Although most norovirus cases resolve without formal medical treatment, individuals with serious medical conditions should seek medical advice immediately.
Prevention Strategies
Prevention remains our best defense against norovirus. Key strategies include rigorous hand hygiene via soap and water, safe food handling practices, and avoiding contact with infected individuals both during and after symptoms. Cleaning surfaces with bleach-containing products is also crucial to effectively controlling viral spread. Notably, norovirus outbreaks often peak in the “norovirus season,” from November to April.
“Eating raw seafood always is a risk for enteric [intestine-related] infections such as norovirus, but compared to the total number of foodborne outbreaks, oyster-related outbreaks make up a small proportion,” explained a senior scientist at the US Centers for Disease Control and Prevention.
With no vaccine currently available, informed precautionary measures are essential. Isolation of infected individuals in high-density living situations, like cruise ships and institutions, can help mitigate large outbreaks. This understanding and proactive approach play a vital role in reducing the impact of norovirus and safeguarding public health.
