Rise in Norovirus Infections Across the United States

Recent reports indicate a significant increase in norovirus outbreaks in various regions of the United States this winter, as documented by the U.S. Centers for Disease Control and Prevention (CDC). The CDC's latest data reveals that during the week of December 5, 2024, there were 91 recorded outbreaks, a notable rise from 69 outbreaks reported in the last week of November. This increase is particularly concerning, as it surpasses the historical average of 65 outbreaks for this time of year.

Norovirus is known to be the predominant cause of foodborne illness in the U.S., accounting for approximately 58% of annual infections. This highly contagious virus spreads rapidly, with just 10 viral particles capable of causing illness in humans. Annually, there are around 2,500 reported norovirus outbreaks, which can occur at any time; however, they are most prevalent between November and April.

The symptoms associated with norovirus infection typically manifest abruptly and include severe vomiting and diarrhea. Additional symptoms may encompass nausea, stomach cramps, body aches, headaches, and fever. The illness generally begins to present itself 12 to 48 hours after exposure to the virus, with most individuals recovering within one to three days.

Norovirus outbreaks are commonly linked to environments where individuals are in close contact, such as cruise ships, nursing homes, correctional facilities, and schools. The virus is primarily transmitted through direct contact with infected individuals, sharing food or utensils, and consuming contaminated food or water, as well as touching contaminated surfaces.

While anyone can contract norovirus, certain demographics are more vulnerable to severe illness, particularly young children, the elderly, and individuals with compromised immune systems. The CDC estimates that norovirus sickness leads to approximately 19 to 21 million infections annually, resulting in around 900 deaths and 109,000 hospitalizations, predominantly among older adults. Young children also experience a significant number of emergency department visits due to norovirus-related dehydration.

Currently, there is no specific medication available to treat norovirus infections. The primary recommendation for managing the illness is rehydration, which involves drinking fluids like water and electrolyte solutions while avoiding caffeine and alcohol. It is crucial for individuals experiencing severe dehydration to seek medical assistance. Signs of dehydration include decreased urine output, dry mouth, throat discomfort, and dizziness when standing up. In children, dehydration may present as excessive sleepiness, irritability, or crying without tears.

To mitigate the risk of norovirus infection, health experts advocate for rigorous handwashing practices. Individuals should wash their hands with soap and warm water for at least 20 seconds, especially before meals and after using the restroom. Additionally, regularly disinfecting surfaces with household cleaning agents is essential to prevent the virus from spreading.