Norovirus is one of the most common causes of viral gastroenteritis, often called the stomach flu. Despite the name, it’s unrelated to influenza. This highly contagious virus spreads easily through contaminated foods, surfaces, or direct contact with an infected person, and it can quickly lead to outbreaks in schools, workplaces, and healthcare settings. Adults infected with norovirus usually experience sudden vomiting, diarrhea, and stomach cramps, which can come on quickly and feel severe. While ...