Stomach Flu Transmission
Certain stomach flu viruses are more common in adults, such as Norwalk virus and noroviruses (see Norovirus). Rotavirus in adults is less common. If adult rotavirus does occur, it is most often seen in:
- Family members of affected children
- The elderly
- People with conditions (or on medications) that decrease the function of the immune system, such as people with HIV, AIDS, or cancer.
People who no longer have symptoms may still be contagious, since the virus can be found in their stool for up to 2 weeks after they recover from their illness. Also, people can become infected without having symptoms and they can still spread the infection.
Food and drinks can easily become contaminated with certain stomach flu viruses. For example, noroviruses easily contaminate food because the virus is so small and because it probably takes fewer than 100 norovirus particles to make a person sick.
Food may be contaminated by food preparers or handlers who have stomach flu, especially if they do not wash their hands regularly after using the bathroom (see Norovirus and Food Handlers). Shellfish may be contaminated by sewage, and people who eat raw or undercooked shellfish harvested from contaminated waters may get diarrhea. Drinking water can also be contaminated by sewage and be a vehicle of transmission of these viruses. Produce items, such as salads and frozen fruit, may also be contaminated at the source.