Norovirus, a highly contagious stomach bug that causes diarrhea and vomiting, is spreading across many states in the U.S., particularly in the Northeast, the Centers for Disease Control and Prevention (CDC) said in a report.

Norovirus outbreaks are expected to occur during late fall, winter, and early spring in the United States. Every year, it causes around 19 to 21 million cases of vomiting and diarrhea, resulting in 109,000 hospitalizations and around 900 deaths.

As per the CDC surveillance data, in the past few weeks, northeastern states have been particularly affected by a surge in norovirus cases, with a three-week average of 13.7%. Meanwhile, the positive test rate in southern states is about 9.4%, 10% in the Midwest, and 12.6% in the western states.

Signs of norovirus:

The signs of infection usually begin within a day or two after exposure to norovirus, and typically last for around one to three days. The most common symptoms include nausea, vomiting, diarrhea, and stomach pain. Norovirus can cause acute gastroenteritis or inflammation of the stomach or intestines, low-grade fever, headache, and muscular pain. Frequent vomiting and diarrhea can lead to dehydration, signs of which include decreased urination, dry mouth and throat, and dizziness.

How contagious is Norovirus?

Norovirus transmission occurs through direct contact with an infected person, ingestion of contaminated food or liquids, touching objects with norovirus and subsequently putting fingers in the mouth, and sharing utensils or cups with infected individuals.

Exposure to even a minimal amount of norovirus particles can lead to illness in an individual. The contagious nature of the infection extends from the time symptoms appear to a few days after recovery. A patient can release billions of norovirus particles through their stool and vomit.

The rapid spread of the virus is particularly notable in enclosed environments such as daycare centers, nursing homes, schools, and cruise ships. Moreover, the virus can stay alive on objects and surfaces for several days or weeks and can survive certain disinfectants.

Who is at risk?

Individuals of all age groups face the risk of contracting the illness. However, young children, the elderly, and people with weakened immune systems are particularly more vulnerable to the infection.

After a bout of norovirus infection, individuals may develop immunity to that specific strain. However, since there are numerous types of norovirus, they continue to be at risk of contracting the infection multiple times throughout their lives.

How to prevent norovirus infection:

  • Maintain proper hand hygiene
  • Clean and disinfect contaminated surfaces
  • Wash contaminated laundry thoroughly
  • Wash fruits and vegetables before cooking
  • Thoroughly cook oysters, shellfish, and other seafood before eating
  • Avoid cooking food or caring for others while infected with the virus


There is no vaccine to prevent infection and no specific treatment for norovirus. Drinking plenty of fluids to prevent dehydration and taking ample rest is the recommended care.