Infectious Norovirus Cases on the Rise Across the United States
Health officials in the United States are reporting a significant increase in cases of the highly contagious norovirus, coinciding with the busy holiday travel period. Recent data from the Centres for Disease Control and Prevention (CDC) reveals that the rate of positive tests for this potentially deadly viral infection has now reached 14 percent. This figure has doubled from the rate recorded just three months ago.
Regional Outbreaks and School Closures
For the week of November 15, approximately 380 cases of norovirus were diagnosed out of more than 2,700 tests conducted. Electronic health records from Epic Research indicate that the majority of infections are concentrated in the central and southern states, including Wyoming, Nebraska, Oklahoma, Texas, and Alabama.
The outbreak has prompted direct action, such as the closure of Wilson Middle School in Wyandotte, Michigan, last week. The state's health department suggested the illness affecting the school was likely norovirus. Dr. Lea Monday, an infectious disease physician at the Detroit Medical Center, explained to CBS Detroit that the decision was a safety measure, stating it's "so easy to spread" that sending everyone home was the best course of action.
Michigan's own weekly disease report confirmed 64 cases of norovirus over the past month, noting a major increase in annual cases since 2021.
Symptoms, Risks, and Winter Surge
While the current national positivity rate is concerning, it remains below the record of 25 percent set in December 2024. Last winter, dozens of outbreaks were reported in early December, primarily driven by the GII.17 strain. Some of these outbreaks were linked to the consumption of raw oysters, which can harbour the virus.
Doctors had anticipated a surge in cases as temperatures drop. Dr. Scott Roberts, a Yale Medicine infectious diseases expert, confirmed that norovirus classically increases in the winter months, largely because people congregate indoors, especially during the holidays.
Typical symptoms of this nasty viral infection include:
- Nausea and stomach pain
- Fever
- Head and body aches
- Diarrhoea and vomiting
These symptoms can lead to severe dehydration and even death. On average, norovirus is responsible for 900 deaths and between 19 and 21 million illnesses each year in the US. Although most people recover within 24 to 72 hours, they can remain contagious and spread the virus for up to two weeks after symptoms appear.
Prevention is Key
Norovirus, often mistakenly called the stomach flu, is notoriously easy to transmit. It can spread through contaminated food, surfaces, and person-to-person contact. Dr. Roberts emphasised that very few norovirus particles are needed to infect a person.
To prevent infection and curb the spread, health officials advise the public to:
- Wash hands thoroughly with soap and water for at least 20 seconds.
- Cook shellfish, like oysters, thoroughly.
- Wash fruits and vegetables before eating.
- Clean and disinfect contaminated surfaces immediately.
- Wash laundry in hot water.
While anyone can be infected, young children under five, older adults, and those with weakened immune systems are at a higher risk of developing severe complications from the virus.
