Norovirus is a highly contagious virus that causes acute gastroenteritis, an inflammation of the stomach and intestines. This common illness, often referred to as “stomach flu,” leads to symptoms such as vomiting and diarrhea. Norovirus poses a significant public health concern, contributing to an estimated 19 to 21 million cases of illness each year in the United States. A notable characteristic of norovirus is its ability to persist in the environment, which contributes to its efficient spread. This environmental resilience allows the virus to remain a threat on various surfaces long after an infected individual has departed.
Survival Durations in Different Environments
On hard, non-porous surfaces like stainless steel, plastic, Formica, and ceramic, norovirus can remain viable for extended periods. Research indicates it can persist for up to 70 days at room temperature on materials like stainless steel and plastic, though other sources suggest a general survival of up to two weeks on surfaces like doorknobs and countertops.
Porous surfaces also present a challenge for containing norovirus spread. On fabrics, carpets, and upholstery, the virus or its surrogates can survive for several days to weeks. Studies using norovirus surrogates on carpets showed survival ranging from less than one day up to 15 days. Generally, norovirus can remain viable on soft surfaces like carpet or fabric for a few days to a week.
Norovirus exhibits prolonged persistence in food and water. It can survive in water for significant durations, ranging from 60 to 728 days depending on the water source, with infectious virus found in groundwater for at least 61 days and genetic material detectable for over three years. Contaminated food items, such as berries, vegetables, fruits, and shellfish, can harbor the virus for one to two weeks.
Norovirus can spread through airborne particles, particularly those generated during vomiting incidents. These fine viral particles can remain suspended in the air, potentially landing on nearby surfaces or being inhaled. The presence of these viral aerosols contributes to the wide dissemination of the virus in contaminated environments.
Infected individuals shed large quantities of the virus in their feces and vomit. Shedding begins with symptom onset and can continue for at least three days after recovery. It can persist for up to two weeks, or even several months, in some cases.
Factors Influencing Survival
Temperature plays a significant role in how long norovirus remains infectious on surfaces. The virus survives longer in colder conditions and can withstand freezing temperatures. While higher temperatures can inactivate the virus, it survives temperatures up to 140°F (60°C), meaning some cooking methods might not be sufficient to eliminate it.
Humidity levels also affect norovirus persistence. Lower humidity levels, around 30% relative humidity, have been observed to favor longer survival of norovirus surrogates on certain surfaces compared to higher humidity.
The type of surface is an important determinant of survival time. Norovirus persists longer on hard, non-porous materials because these surfaces offer less opportunity for the virus to be absorbed or degraded, providing a more stable environment. Conversely, porous surfaces allow for greater interaction with environmental elements, potentially leading to faster degradation, though they can still harbor the virus for days to weeks.
The presence of organic matter, such as vomit, feces, or food particles, enhances norovirus survival. These materials act as a protective barrier for the virus, shielding it from drying and making it more resistant to cleaning agents and disinfectants. This protection allows the virus to maintain its infectiousness for longer periods.
Norovirus is resistant to many common disinfectants and alcohol-based hand sanitizers, meaning not all cleaning products are effective against it. Certain disinfectants, such as bleach solutions, are necessary for proper inactivation and effective removal of the virus from contaminated environments.
Preventing Norovirus Spread
Effective hand hygiene is a primary defense against norovirus transmission. Thorough handwashing with soap and water for at least 20 seconds is recommended, particularly after using the restroom or changing diapers, and before preparing or eating food. Alcohol-based hand sanitizers are less effective against norovirus compared to proper handwashing with soap and water.
Regular surface disinfection is important in preventing spread. Contaminated surfaces should be cleaned with a bleach solution or EPA-approved disinfectants effective against norovirus. First clean visible vomit or fecal matter, then apply the disinfectant to high-touch surfaces like doorknobs, light switches, and countertops.
Food safety practices help limit the spread of norovirus through contaminated food. Individuals sick with norovirus should avoid preparing food for others for at least 72 hours after symptoms have resolved. Washing fruits and vegetables thoroughly and cooking shellfish completely reduces the risk of foodborne transmission.
Isolating sick individuals helps contain outbreaks. People experiencing norovirus symptoms should stay home from work, school, or other public gatherings to prevent further transmission. Ensuring sick individuals have separate facilities or limiting their contact with others also reduces the virus’s spread within a household or institution.
Proper laundry care for contaminated items helps eliminate the virus. Clothing, linens, and other washable materials that may have come into contact with vomit or feces should be washed using hot water and detergent. This practice helps inactivate the virus and prevent its spread through contaminated fabrics.