Norovirus infections are spiking across the country, with preliminary data from the Centers for Disease Control and Prevention (CDC) indicating this season could see unprecedented levels of illness. The highly contagious virus, known for causing rapid-onset vomiting and diarrhea, is already spreading at a faster rate than in previous years.
Early Data Shows Alarming Increase
As of mid-November, roughly 14% of norovirus tests came back positive – a significant jump from the 10% seen during the same period last year. Experts warn that this early surge suggests a particularly severe season, potentially rivaling or exceeding last year’s already high infection rates.
“We’re on track to have a similar or worse year,” says Donald Schaffner, PhD, chair of food science at Rutgers University, highlighting the potential for widespread disruption.
Why Norovirus Peaks in Winter
Norovirus circulation isn’t limited to colder months, but infections typically peak between December and March. This seasonal pattern is linked to increased indoor crowding, which facilitates transmission. Last year, the virus reached a record high positive test rate of nearly 25% in December, illustrating the scale of potential outbreaks.
Frank Yiannas, former deputy commissioner for food policy at the FDA, notes that while November increases are not unusual, the current positive rates are higher than previously observed. Vigilance is particularly important in settings where the virus spreads easily, such as food service and healthcare facilities.
A New Strain Drives Infections
The rise in cases is partly attributed to a new, dominant strain of norovirus, GII.17. For years, GII.4 was the most common variant. However, GII.17 now accounts for approximately 75% of outbreaks, up from just 10% in the previous season.
This shift is concerning because populations lack immunity to the new strain, making them more susceptible to infection. The virus evolves rapidly, meaning new strains emerge frequently, bypassing existing protection.
Symptoms and Spread: What You Need to Know
Norovirus symptoms usually appear 12-48 hours after exposure and include:
- Nausea
- Vomiting
- Stomach cramps
- Diarrhea
- Low-grade fever
- Muscle aches
The virus is incredibly contagious, spreading through contact with infected individuals or contaminated surfaces. Transmission occurs when microscopic fecal or vomit particles enter the mouth, often via contaminated food, water, or surfaces.
Preventing Infection: Key Steps
There is no cure for norovirus; the infection must run its course. However, symptoms can be managed with fluids, rest, and bland foods.
The most effective prevention measures include:
- Frequent handwashing for at least 20 seconds with soap and water, especially after restroom use and before eating.
- Avoiding food preparation or caring for others while sick (remain symptom-free for at least 48 hours).
- Properly disinfecting surfaces that may be contaminated.
Conclusion
The current surge in norovirus cases, driven by a new strain and early high infection rates, poses a significant public health concern. Enhanced vigilance, particularly in communal settings, coupled with strict hygiene practices, is crucial to mitigating spread. While the infection is unpleasant but typically short-lived, the potential for widespread outbreaks warrants proactive prevention.
