An infection is thought to be the underlying cause of a lot of irritable bowel syndrome nowadays. Think of it like this: a person gets an infection – whether it’s food poisoning or a virus that they caught from a friend or a loved one. They get sick – nausea, vomiting, abdominal pain, diarrhea. That bug does something to the digestive tract and after that, the bowels are never the same. People can have symptoms of IBS (bloating, cramping, diarrhea, constipation) and it’s as a result of that original insult, an original infection that they had. The infection’s gone but the effects on the digestive tract can last months or years.