Norovirus is a highly contagious virus that frequently causes acute gastroenteritis, commonly known as the “stomach flu.” This illness leads to symptoms such as vomiting, diarrhea, nausea, and abdominal cramps. Understanding how this widespread virus spreads is important for public health, particularly concerning transmission through saliva. This article explores how norovirus moves between people and the role saliva might play.
Primary Transmission Routes of Norovirus
Norovirus primarily spreads through the fecal-oral route, involving ingesting microscopic particles of an infected person’s stool. This can happen through contaminated food or water, or by touching contaminated surfaces and then one’s mouth. Raw or undercooked shellfish, fruits, and vegetables are particularly susceptible to contamination.
Another significant route involves aerosolized virus particles, especially from vomit. When an infected individual vomits, tiny droplets containing the virus can become airborne, contaminating nearby surfaces or being inhaled directly by others. This airborne transmission contributes to the spread of norovirus in confined or crowded settings.
The Link Between Norovirus and Saliva
Recent scientific investigations confirm norovirus presence in the saliva of infected individuals. Studies have detected norovirus RNA in saliva samples from both symptomatic patients and, to a lesser extent, from asymptomatic individuals.
Norovirus genogroup II (GII) infections show a higher detection rate in saliva samples compared to genogroup I (GI). For GII infections, norovirus was detected in about 17.9% of saliva samples from symptomatic cases and approximately 5.2% of asymptomatic individuals in some studies. The virus was detected in saliva regardless of a person’s secretor status.
Assessing the Transmission Risk from Saliva
While norovirus can be detected in saliva, its viral load is generally much lower than what is found in feces or vomit. Stool samples typically contain significantly higher viral loads, often in the billions of particles per gram.
Transmission through saliva is biologically possible, for instance through direct contact like kissing or sharing eating utensils. However, it is considered a much lower risk pathway compared to the primary routes. The lower viral concentration in saliva means it is not a major driver of norovirus outbreaks. The vast majority of infections still occur through contact with fecal matter or vomit.
Effective Prevention Strategies
Effective prevention methods focus on interrupting primary transmission routes. Frequent and thorough handwashing with soap and water for at least 20 seconds is recommended, especially after using the toilet or caring for someone sick, and before eating or preparing food. Alcohol-based hand sanitizers can be used in addition to handwashing, but are not as effective against norovirus alone.
Proper cleaning and disinfection of contaminated surfaces are also important. After someone vomits or has diarrhea, the affected area should be immediately cleaned and disinfected using a chlorine bleach solution. Soiled laundry should be handled carefully, washed with detergent and hot water at the maximum cycle length, and then machine dried at the highest heat setting. Avoiding sharing food, drinks, or kissing someone ill with norovirus can serve as a secondary precaution.