Norovirus is a highly contagious virus that causes acute gastroenteritis, an illness marked by sudden onset of vomiting and diarrhea. It is a widespread cause of illness globally and frequently responsible for outbreaks in various settings. Understanding how norovirus spreads is important for preventing its transmission, including considering scenarios like kissing.
How Norovirus Spreads
Norovirus primarily spreads through the fecal-oral route, where the virus is shed in the feces and vomit of infected individuals and then ingested by another person. This occurs directly through person-to-person contact, or indirectly via contaminated food, water, or surfaces. The virus is robust and can survive on surfaces for days or even weeks.
The infectious dose of norovirus is extremely low; as few as 10 to 100 viral particles can cause infection. This low dose significantly contributes to its highly contagious nature, allowing it to spread quickly. People are most contagious when symptomatic, but can shed the virus for two weeks or more after symptoms resolve. Asymptomatic individuals can also spread the virus.
Contaminated food and water are common sources of outbreaks. Food becomes contaminated if an infected person handles it without proper hand hygiene, or if produce is irrigated with contaminated water. Water sources can be contaminated by sewage leaks or if an infected person vomits or has diarrhea in recreational water. Environmental contamination also plays a role, as tiny drops of vomit or diarrhea can contain millions of viral particles, landing on surfaces and then being transferred to people’s mouths.
Risk of Transmission Through Kissing
While kissing is not a primary direct route of norovirus transmission via saliva, it can facilitate indirect transmission. This is due to close proximity and potential contact with contaminated hands or aerosolized particles. The main concern remains the fecal-oral nature of the virus, even in close contact scenarios.
Transmission can occur if an infected person has unwashed hands that have come into contact with their own feces or vomit, then touches another person’s face or mouth during kissing. The virus can also persist on surfaces; if lips or hands touch a contaminated surface and then transfer the virus during kissing, it can lead to infection.
When an infected person is actively vomiting, aerosolized norovirus particles can be generated and dispersed into the air. These tiny airborne particles, numbering in the millions from a single episode, can be inhaled or land on the mucous membranes of another person in close proximity, potentially leading to infection. While less common than direct or indirect contact, airborne transmission is a recognized pathway, particularly in enclosed spaces.
Reducing Your Risk of Norovirus
Thorough hand hygiene is important for norovirus prevention. Wash hands frequently with soap and water for at least 20 seconds, especially after using the restroom, before eating or preparing food, and after caring for someone sick. Alcohol-based hand sanitizers are generally less effective against norovirus compared to soap and water because norovirus is a non-enveloped virus, making it more resistant to alcohol.
Cleaning and disinfecting contaminated surfaces are also important preventative measures. After someone vomits or has diarrhea, the affected area should be cleaned immediately using rubber or disposable gloves. Disinfection should follow with a chlorine bleach solution, such as 5 to 25 tablespoons of household bleach per gallon of water. The surface should remain wet with the bleach solution for at least five minutes before being rinsed with soap and hot water.
To prevent further spread, individuals with norovirus symptoms should avoid close contact with others, including kissing. They should also stay home from work, school, or public gatherings. Additionally, avoid preparing food for others for at least two to three days after symptoms resolve, as viral shedding can continue.