A few days up to two weeks or more.
After approximately 1 to 2 days, depending on the virus, stomach flu symptoms can appear. This period between the stomach flu transmission and the start of symptoms is the stomach flu incubation period.. In some cases, the stomach flu incubation period can be as short as 4 hours. Norovirus. Norovirus is the most common cause of stomach flu. Most people are contagious from the moment that they become ill. Much of the symptoms start appearing within a day or three days of getting exposed; some people are known to be contagious up about two weeks after recovering from the illness. With a norovirus infection (including Norwalk virus), a person is not usually contagious during the stomach flu incubation period. People infected with norovirus gastroenteritis are usually contagious from the moment they begin feeling ill to at least 3 days after recovery. 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 — the time during which a sick person can give the illness to others — is slightly different for each virus. 1  Norovirus. 2  With norovirus — the most common cause of viral gastroenteritis in adults and children — you're contagious from the moment you begin to feel ill. For example, with a rotavirus infection, the person is contagious during the stomach flu incubation period. This person is also contagious while experiencing stomach flu symptoms. Once the diarrhea has ended, a person with rotavirus gastroenteritis is no longer contagious.
http://diarrhea.emedtv.com/stomach-flu/stomach-flu-incubation-period.html http://healthresearchfunding.org/stomach-flu-incubation-period/ http://diarrhea.emedtv.com/stomach-flu/stomach-flu-p2.html http://www.mayoclinic.org/diseases-conditions/viral-gastroenteritis/expert-answers/stomach-flu/faq-20057899 http://diarrhea.emedtv.com/stomach-flu/stomach-flu-incubation-period.html
contagious period for gastro