Norovirus is a highly contagious virus that causes gastroenteritis, an inflammation of the stomach and intestines often mistakenly called the “stomach flu.” This illness is the leading cause of acute viral gastroenteritis in the United States. Infants can get norovirus, and they are particularly vulnerable to its complications. This is due to their immature immune systems and small body mass, which makes them highly susceptible to rapid dehydration.
Infant Vulnerability and Distinct Symptoms
Infants are vulnerable to norovirus because their bodies have a small reserve of fluids and electrolytes. This means they can become dangerously dehydrated much faster than older children or adults. Non-verbal infants present symptoms through specific physical changes that parents must recognize, as they cannot communicate thirst or nausea. Symptoms often appear suddenly, typically 12 to 48 hours after exposure, and include forceful vomiting and watery diarrhea.
The most concerning signs indicate rapid fluid loss, which can become a medical emergency. Parents should monitor for fewer wet diapers, meaning no wetness for six to eight hours. Other signs of dehydration include:
- A dry mouth and tongue.
- A sunken soft spot (fontanelle) on the head.
- Crying without producing tears.
- Unusual sleepiness, excessive fussiness, or a complete lack of energy.
How Norovirus Spreads
Norovirus is extremely contagious, requiring only a very small number of virus particles to cause an infection. The virus is primarily spread through the fecal-oral route, meaning tiny traces of stool or vomit from an infected person are ingested by another person. Infected individuals shed billions of virus particles in their stool and vomit, often before symptoms appear and for up to two weeks after they feel better.
Infant environments like daycare centers are common settings for explosive outbreaks due to frequent diaper changes and shared toys, which become contaminated surfaces (fomites). Norovirus is a hardy virus that can survive on surfaces for days or weeks, making environmental contamination a major transmission pathway. The virus can also spread through microscopic droplets in the air following a vomiting episode, contaminating nearby surfaces and objects.
Essential Care and When to Seek Medical Help
There is no specific medication to treat norovirus; care focuses entirely on managing symptoms and preventing dehydration. The most important intervention is the frequent, small administration of an oral rehydration solution (ORS), such as Pedialyte. These solutions contain the precise balance of water, salts, and sugar needed to replace lost electrolytes and fluids.
Infants should continue to be fed breast milk or formula. Caregivers must avoid giving plain water, fruit juice, or soda, as these can worsen diarrhea and electrolyte imbalance. Fluids should be offered in very small amounts—about one to two ounces every one to two hours—to ensure absorption and prevent the vomiting reflex from being triggered.
Immediate medical attention is necessary if an infant shows signs of severe dehydration or other complications. Seek emergency care if the infant:
- Has a high fever or bloody diarrhea.
- Is vomiting green or bloody stomach contents.
- Is unable to keep any liquids down.
- Appears floppy or unresponsive, or has not produced a wet diaper in eight hours or more.
Preventing the Spread
Meticulous hygiene is required because the virus is resistant to many common disinfectants. Hand washing with soap and water is the single most effective action, particularly after changing a diaper or cleaning up after a sick child. Alcohol-based hand sanitizers are generally not effective against norovirus and should not be relied upon as the sole method of cleaning.
Contaminated surfaces must be disinfected with a bleach-based cleaner or an EPA-registered product specifically labeled as effective against norovirus. A common household bleach solution of five to 25 tablespoons per gallon of water is effective, but it must remain on the surface for at least five minutes before wiping. Soiled clothing and bedding should be immediately removed and washed using detergent and the highest heat setting available, followed by machine drying at the highest heat.