It is well established that Irritable Bowel Syndrome (IBS) can develop following a gastrointestinal infection. In Bergen, Norway, in 2004, there was an outbreak of Giardia from a contaminated water source. Researchers followed 1252 laboratory confirmed cases of Giardia for 6 years and also 2500 age-matched individuals from Bergen who did not contract Giardia. Of the group who had (and cleared) Giardia, 43 % developed IBS over 6 years compared to 14% of the group who did not get Giardia. In the four subsequent years, almost no new cases of IBS arose. From Clinical Gastroenterology and Hepatology July 2018.