Norovirus is a common cause of gastroenteritis, an inflammation of the stomach and intestines that leads to symptoms like nausea, vomiting, diarrhea, and abdominal pain. These symptoms appear 12 to 48 hours after exposure and last for one to three days. Understanding how long this virus can survive outside the body is important for preventing its transmission.
Norovirus Persistence
Norovirus remains infectious in various environments for extended periods. On hard, non-porous surfaces like countertops and doorknobs, the virus can persist for up to two weeks, with some studies showing survival for up to 42 days on food contact surfaces. On porous materials like fabrics and carpets, it persists for several days, up to 12 days on contaminated carpet.
The virus also survives in food and water, which contributes to its spread. In contaminated food, norovirus does not multiply but remains infectious. It is resistant to heat, surviving temperatures up to 145°F (60°C). This means quick steaming of foods like shellfish may not eliminate it. In water sources, norovirus persists for weeks to several months, potentially years in still water. It survives in chlorine concentrations up to 10 ppm, exceeding levels in municipal drinking water.
Infected individuals contribute to the virus’s prolonged presence in the environment. People are contagious from the moment symptoms begin and shed viral particles in their stool for at least several days after symptoms resolve. This shedding may last for up to two weeks after recovery, and in individuals with other medical conditions, it can extend for several weeks to months. Even those who experience no symptoms can still shed the virus and transmit it to others.
The norovirus’s ability to endure in diverse conditions is due to its outer protein shell, a capsid. This protective layer allows it to withstand temperature fluctuations, from freezing to high heat, and makes it resistant to many common disinfectants, including alcohol-based hand sanitizers. Its resilience requires effective removal from surfaces and prevention of transmission.
Stopping Norovirus Spread
Effective hand hygiene is key to preventing norovirus transmission. Washing hands thoroughly with soap and water for at least 20 seconds effectively removes viral particles. Alcohol-based hand sanitizers are less effective against norovirus compared to proper handwashing, as they do not break down the virus’s protective structure.
Disinfecting surfaces helps control norovirus spread. Any visible vomit or fecal matter should be removed carefully first, wearing gloves and a mask to prevent aerosolization. Subsequently, surfaces should be disinfected using a bleach-based solution. The Centers for Disease Control and Prevention (CDC) recommends a chlorine bleach solution with a concentration of 1,000 to 5,000 parts per million (ppm), which translates to about 5 to 25 tablespoons of 5-8% household bleach per gallon of water. This solution must remain on the affected surface for at least 5 minutes; some guidelines suggest 10 to 20 minutes before wiping. For porous surfaces like carpets and upholstery, steam cleaning at high temperatures can be an effective alternative to bleach, which may cause damage.
Food safety practices are also important in preventing norovirus outbreaks. Shellfish, a common source of infection, should be cooked thoroughly to an internal temperature of at least 145 degrees Fahrenheit, as quick steaming alone is not sufficient to inactivate the virus. All fruits and vegetables should be washed thoroughly before consumption. Individuals sick with norovirus should avoid preparing food for others for at least 48 hours after symptoms cease.
When an individual is sick, isolating them and managing contaminated items promptly helps limit spread. Soiled clothing and linens must be removed immediately, handled with gloves, and washed separately. Use detergent and hot water at the maximum cycle length, followed by machine drying at the highest heat setting. Contaminated disposable items should be placed in sealed plastic bags and discarded.