Norovirus is a common cause of acute gastroenteritis, often referred to as “stomach flu,” though it is not related to the influenza virus. It is highly contagious and responsible for widespread outbreaks, particularly in closed environments like cruise ships, nursing homes, and schools. A common misconception surrounds how this virus spreads, specifically whether it is airborne.
Norovirus is generally not an airborne pathogen like measles or tuberculosis, which travel long distances on microscopic particles. While norovirus particles can become aerosolized, this occurs when tiny liquid droplets containing the virus are generated, often during forceful vomiting or diarrhea. These droplets typically travel only short distances, usually within a few feet of the infected individual, before settling onto surfaces.
The short-range spread of these aerosolized droplets can lead to localized contamination of surfaces and direct exposure to others in close proximity. While aerosolization can contribute to norovirus spread in specific, close-proximity scenarios, it is not considered the primary or most common mode of general transmission. The virus is also remarkably resilient, capable of surviving on surfaces for days or weeks, and only a very low number of virus particles are needed to cause infection.
Primary Modes of Norovirus Transmission
The most common way norovirus spreads is through the fecal-oral route, involving the transfer of microscopic fecal particles from an infected person to the mouth of another. This occurs directly through person-to-person contact, such as caring for a sick individual or touching an infected person’s hands before touching one’s own mouth.
Indirect contact also plays a major role in transmission, often involving contaminated surfaces, known as fomites. An infected person might touch objects such as doorknobs, light switches, or utensils, leaving virus particles behind. When another person touches these contaminated objects and then touches their mouth, nose, or eyes, infection can occur.
Contaminated food and water are frequent sources of norovirus outbreaks. Food can become contaminated if handled by an infected person who has not washed their hands, especially raw or uncooked items like salads or bakery goods. Water sources, such as wells or municipal systems, can become contaminated with sewage containing the virus, leading to widespread illness. Shellfish and produce from contaminated waters are also implicated in outbreaks.
Protecting Yourself and Others
Protecting against norovirus infection and limiting its spread relies on hygiene practices. Thorough handwashing with soap and water is important, especially after using the restroom, changing diapers, or before preparing or eating food. Alcohol-based hand sanitizers are generally less effective against norovirus compared to soap and water, as they may not fully inactivate the virus.
Cleaning and disinfecting contaminated surfaces are important steps in prevention. After an episode of vomiting or diarrhea, surfaces should be cleaned promptly and thoroughly using a bleach-based cleaner or a disinfectant labeled as effective against norovirus. Follow the product’s instructions for concentration and contact time to ensure effective disinfection.
Practicing good food safety habits can further reduce transmission risk. This includes washing fruits and vegetables thoroughly, cooking shellfish to a safe internal temperature, and avoiding preparing food for others if ill. If someone in a household has norovirus, isolating them if possible and avoiding sharing personal items like towels or eating utensils can help prevent further spread. While most norovirus infections resolve on their own, seek medical attention if signs of severe dehydration, such as decreased urination, dizziness, or excessive thirst, become apparent.