Norovirus, commonly known as the “stomach flu,” is a highly contagious virus that causes acute gastroenteritis. This illness typically involves symptoms like vomiting, diarrhea, nausea, and abdominal pain. While symptoms usually resolve within one to three days, the virus’s ability to persist on surfaces significantly contributes to its widespread transmission. Understanding how long norovirus remains viable on environmental surfaces is important for controlling its spread.
Norovirus Survival on Surfaces
Norovirus can survive for extended periods outside a human host due to its resilience. The virus can persist on various inanimate surfaces for days to weeks. On hard, non-porous surfaces such as plastic, stainless steel, ceramic, and Formica, norovirus can remain infectious for more than two weeks, with some studies indicating survival for up to 42 days. This persistence on common surfaces like countertops and doorknobs highlights its potential for indirect transmission.
Soft, porous surfaces also pose a risk for norovirus persistence. Norovirus can remain viable on carpets and fabrics for a few days to a week. Some research suggests that norovirus can survive on carpet fibers for up to 60 days, depending on the material and humidity. This durability highlights the challenge in eliminating the virus from diverse environments.
Factors Affecting Norovirus Persistence
Several environmental factors influence how long norovirus can remain infectious on surfaces. Temperature plays a role, as the virus generally survives better in cooler conditions. Studies show increased persistence at lower temperatures, such as 7°C, compared to warmer room temperatures. This characteristic contributes to norovirus outbreaks often occurring in cooler months.
Humidity also affects viral survival, with norovirus able to persist across a range of humidity levels. While some studies suggest better preservation at low humidity, others indicate varying effects depending on the specific conditions. The type of surface is another factor, as porous materials like wood or fabric can sometimes protect the virus differently than smooth, non-porous surfaces like metal or plastic.
The presence of organic matter, such as vomit or fecal particles, can further extend norovirus survival. These substances provide a protective barrier for the viral particles, shielding them from environmental degradation. This protection makes thorough cleaning and disinfection particularly important in areas contaminated with bodily fluids.
Minimizing Norovirus Transmission from Surfaces
Effective cleaning and disinfection protocols are essential to prevent norovirus spread. First, clean visible soil or organic matter from surfaces, as this debris can reduce disinfectant effectiveness. After cleaning, disinfect surfaces using products effective against norovirus.
Chlorine bleach solutions are recommended for inactivating norovirus. A common dilution for non-porous surfaces is 5 to 25 tablespoons of household bleach (5% to 8%) per gallon of water, creating a solution of 1,000 to 5,000 parts per million (ppm). The solution needs to remain on the surface for a specific contact time, typically at least five minutes, for effectiveness. For porous surfaces, a higher concentration of bleach may be needed. The Environmental Protection Agency (EPA) maintains a list of registered products effective against norovirus; always follow their label directions, including contact time.
Beyond surface disinfection, frequent and thorough handwashing is important. Washing hands vigorously with soap and water for at least 20 seconds is more effective against norovirus than alcohol-based hand sanitizers. This is because scrubbing with soap and water physically removes viral particles, and norovirus is resistant to alcohol. Handwashing is important after using the bathroom, changing diapers, and before preparing or eating food.