If you’ve ever had a bout of food poisoning, traveler’s diarrhea, or “stomach flu,” only to have some of the symptoms linger for a long time — or show up a few months after you thought you were better — you may have been confused, frustrated, and anxious. What may not have crossed your mind is that you suddenly developed irritable bowel syndrome (IBS). Specifically, post-infectious IBS.
Irritable bowel syndrome (IBS) is a disorder of the gut-brain interaction that is exacerbated by stress, dietary factors, and changes in the gut microbiome. While your bowels (intestines) are not working normally, Their structure remains normal. IBS causes abdominal pain with diarrhea, constipation, or both and affects about 1 in 10 people in the U.S.
While most people with IBS can’t pinpoint when their symptoms started, some people know exactly when they started—right after they’ve been out of action for a while with bowel problems.
Postinfectious IBS occurs after an episode of what is technically called gastroenteritisan inflammation of the intestinal lining caused by bacteria, virus or other pathogen. Research shows that up to 30 to 40 percent of people who suffer from a sudden episode of gastroenteritis develop post-infectious IBS.
What causes postinfectious IBS?
Many pathogens responsible for gastroenteritis can also cause postinfectious IBSincluding norovirus and Giardia, a protozoan often found in contaminated food or water. It may also follow a case of “traveler’s diarrhea” where the exact culprit is not clear.
Postinfectious IBS may persist for several months or even several years after the initial illness, although IBS caused by norovirus generally resolves much sooner. There can also be a time lag between the initial infection and the onset of IBS symptoms—research suggests that the likelihood of developing post-infectious IBS is high even three years after the initial illness—making it difficult to connect the dots.
How does something as common (albeit unpleasant) as food poisoning lead to IBS? The pathogen responsible for your illness can disrupt both your gut microbiota and your gut lining, activating the immune system and causing low-grade inflammation. It also increases intestinal motility – which basically means that everything you eat and drink passes through you faster. All of these can cause diarrhea and other symptoms to linger long after the pathogen is gone.
The risk of developing postinfectious IBS appears to be higher with severe cases of gastroenteritis, especially if symptoms include prolonged or bloody diarrhoea, fever or weight loss or if antibiotic treatment has been necessary. Having depression, anxiety, or stressful life events in the three months before the initial infection can prolong IBS.
Diagnosis and treatment of postinfectious IBS
Because there is no test for IBS, diagnosis begins with an assessment of current symptoms and making sure there are no symptoms that suggest more serious gastrointestinal conditions, such as inflammatory bowel disease (Crohn’s disease and ulcerative colitis) and celiac disease.
The main symptoms of IBS are abdominal pain for at least one day a week, on average, for the past three months, with symptoms starting at least six months agoalong with at least two of these criteria:
- Change in stool frequency,
- Change in the appearance of stool,
- Pain associated with defecation
Most people with IBS also experience bloating that worsens with meals, fluctuates in intensity, and worsens at the end of the day before settling down at night. However, bloating is a common occurrence for countless reasons, so bloating alone is not considered a symptom of IBS. Bloating is also not necessary to diagnose IBS.
Postinfectious IBS will resolve gradually and spontaneously in most people without treatment, but since IBS can significantly affect quality of life, treatment is a good idea. IBS can be treated with prescription drugs or diet. The main dietary treatment is temporary restriction of fermentable carbohydrates through a FODMAP (fermentable oligo- and monosaccharides and polyols) elimination diet followed by a reintroduction phase to see which FODMAPs are causing symptoms.
Carrie Dennett, MPH, RDN, is a registered dietitian nutritionist based in the Pacific Northwest, journalistintuitive nutrition consultant, authorand speaker. Her superpowers include; debunking nutritional myths and empowerment of women and men feel better about their bodies and make food choices that support pleasure, nutrition and health. This post is for informational purposes only and does not constitute personalized nutrition or medical advice.
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