The autonomic nervous system (ANS) regulates the functions of our internal organs (the viscera) such as the heart, stomach and intestines.
The flu is contagious a day before and five days to a week after its onset. Young children, people over 65, those with compromised immune systems, and people with a terminal illness are at risk of death from the 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. Some people may be contagious for up to two weeks after recovery. 2  Rotavirus. 3  Symptoms of rotavirus â the leading cause of viral gastroenteritis in infants and young children â usually appear one to three days after exposure.