What is Post-Infectious IBS?
The observation that the onset of IBS symptoms can be precipitated by gastrointestinal infection dates back to the 1950s. Mechanisms are not known but include changes in the microbiome, use of antibiotics to treat the infection, and an increase in enteroendocrine cells.
Several meta-analyses (studies that combine results from previously published research studies and analyze the larger number) have demonstrated an increased risk of IBS in patients after acute gastroenteritis. The most recent meta-analysis of 18 studies reported an incidence of IBS of 10% after acute gastroenteritis.
One important, large prospective study was done in a community in Canada, where the town folks of Walkerton were exposed to contaminated drinking water after a heavy rainfall. Pathogens identified in the water included Shiga-toxin-associated E. coli (STEC) and Campylobacter jejuni. Over seven thousand individuals were exposed, and there were 904 cases of self-reported gastrointestinal symptoms. When the affected individuals were followed for up to two years, 28% developed symptoms of IBS, compared with 10% of controls who did not have diarrhea.
Risk factors associated with the development of post-infectious IBS include female gender, younger age, prolonged fever, longer duration of the acute infectious illness, and preexisting anxiety and depression. As with non-post-infectious IBS, the precise mechanism that produces the symptoms is not specifically known.