The Don Julio’s mexican restaurant in Corinth, Mississippi has been linked to at least 59 confirmed Salmonella illnesses, and likely many more unconfirmed illnesses.  If the existing medical literature on the subject is accurate, the Don Julio’s Salmonella outbreak will cause many of those victims–between 7 and 30%, according to some studies–to develop a condition called post-infectious irritable bowel syndrome. 

Irritable bowel syndrome (IBS) is one disorder in a spectrum of common functional gastrointestinal disorders. Symptoms of IBS can include constipation, diarrhea, alternating diarrhea and constipation, abdominal pain, urgency, bloating, straining at stools, and a sense of incomplete evacuation. The Rome III definition for IBS, which is widely accepted in the medical community, is recurrent abdominal pain or discomfort at least three days per month for at least three months, with at least two of the following symptoms also present: improvement of the pain or discomfort with defecation, a change in frequency of stools, or a change also in the form or appearance of stool.

The observation that the onset of IBS symptoms can be precipitated by gastrointestinal infection dates to the 1950s. Different studies have shown that 7-31% of individuals who have experienced an episode of infectious gastroenteritis, whether bacterial or viral, may develop symptoms of IBS.

One recent meta-analysis (a study that combines results from previously published research studies and analyzes the larger number) of 8 studies published between 1950 and 2005 found a positive association between gastrointestinal infection and the onset of IBS in 6 of the studies. In this meta-analysis alone, the average occurrence of post-infectious IBS was 9.8%, compared to 1.2% in the control group. This equates to a sevenfold increase in the odds of developing IBS after gastrointestinal infection.

There appear to be several risk factors associated with the development of post-infectious IBS, including female sex, severity and duration of the acute infectious illness, whether the person suffered from bloody stools, and psychological profile. As with non-post-infectious IBS, the precise mechanism that produces the symptoms is not specifically known. The pathogens known to precipitate post-infectious IBS symptoms include specifically, though not necessarily exclusively, Enterotoxigenic E. coli strains, Shiga toxin-producing E. coli strains (including E. coli O157:H7), Campylobacter, Shigella, and Salmonella.