how contagious is a stomach flu
You can be contagious from a few days up to two weeks or more, depending on which virus is causing your stomach flu (gastroenteritis).A number of viruses can cause gastroenteritis, including noroviruses and rotaviruses.The contagious period â the time during which a sick person can give the illness to others â is slightly different for each virus. 1  Norovirus.2  With norovirus â the most common cause of viral gastroenteritis in adults and children â you're contagious from the moment you begin to feel ill. number of viruses can cause gastroenteritis, including noroviruses and rotaviruses. The contagious period â the time during which a sick person can give the illness to others â is slightly different for each virus.