What Is Norovirus? When someone talks about having “the stomach flu,” they are probably describing acute-onset gastroenteritis caused by one of the noroviruses, which are members of the “calcivirus” family (Caliciviridae).[1] Noroviruses are entirely unrelated to influenza viruses.[2] The Centers for Disease Control and Prevention (CDC) estimates that noroviruses cause nearly 21 million cases of acute…
