Stomach Flu Symptoms 2024 Adults. Gastroenteritis can be caused by viruses, most commonly norovirus, bacteria and parasites. It's caused by viruses that cause inflammation of the stomach and intestines.
Your doctor will likely diagnose viral gastroenteritis (stomach flu) based on symptoms, a physical exam and sometimes on the presence of similar cases in your community. Fortunately, it usually resolves within a few days, but.