Norovirus Cases Surge: Essential Tips for Protection and Understanding the Outbreak
Norovirus is rapidly spreading across the United States as the holiday season approaches. This highly contagious virus has seen a significant increase in cases since mid-October, particularly in states such as Louisiana, Michigan, and Indiana. Data from the WastewaterSCAN program, a collaboration between Stanford University and Emory University, reveals that norovirus concentrations in wastewater have risen by 69% nationwide since last month.
Current Norovirus Outbreak Trends
As of November 21, the Northeast and Midwest regions show particularly high norovirus activity. Amanda Bidwell, the scientific program manager for WastewaterSCAN, states that the current levels are concerning but not as severe as last year’s spike. In 2024, the GII.17 variant was responsible for a substantial number of outbreaks, which may have mutated to increase its transmissibility.
- 235 reported norovirus outbreaks from August to November 2024.
- 153 outbreaks reported during the same timeframe this year.
The Centers for Disease Control and Prevention (CDC) is actively monitoring the situation, especially since norovirus outbreaks typically peak between November and April. However, there is a discrepancy between the CDC’s reports and the data from WastewaterSCAN, with the latter providing a more comprehensive overview of the virus’s spread.
Understanding Norovirus Variants
Norovirus has been primarily associated with the GII.4 strain for over three decades. Recently, variant GII.17 has emerged as a dominant strain, constituting about 75% of outbreaks last year. Experts believe the early onset of this year’s outbreaks in October may be attributed to the rise of GII.17.
Dr. Robert Atmar from Baylor College of Medicine suggests that both enhanced transmissibility of the virus and a lower immunity in the population could be contributing factors to the current surge. Meanwhile, Dr. Craig Wilen from Yale University notes that the lower immunity among the population may explain the variant’s effectiveness, rather than increased transmissibility alone.
Symptoms and Prevention of Norovirus
Norovirus, often dubbed the “winter vomiting disease,” leads to around 20 million infections annually in the U.S. It is responsible for more than half of foodborne illnesses in the country. The virus spreads through contaminated food, water, surfaces, and direct contact with an infected person.
- Main symptoms include:
- Diarrhea
- Vomiting
- Fever
- Stomach pain
- Body aches
Symptoms generally manifest 12 to 48 hours after exposure, lasting for several days. Individuals can remain contagious for more than two weeks, even post-recovery.
Effective Protection Against Norovirus
Norovirus is notoriously resilient and can survive temperatures up to 145°F, thus earning the title of the “perfect pathogen.” Hand sanitizers that are effective against other viruses may not work well on norovirus. To effectively eliminate the virus, the CDC recommends:
- Thorough handwashing with soap.
- Using diluted bleach to clean contaminated surfaces.
- Washing contaminated clothing with hot water and detergent.
Additionally, it is vital to properly clean fruits and vegetables and ensure that shellfish is cooked correctly. While there is no specific antiviral treatment for norovirus, maintaining hydration is crucial for recovery. A Phase 3 Moderna trial is currently underway to develop a vaccine against norovirus, providing hope for future prevention.
