causes of infectious diarrhoea
Diarrhoea is usually a symptom of gastroenteritis (a bowel infection), which can be caused by: 1  a virus â such as norovirus or rotavirus. 2  bacteria â such as campylobacter, Clostridium difficile (C. 3  parasites â such as the Giardia intestinalis parasite that causes giardiasis.