What is Post-Infectious Irritable Bowel Syndrome (PI-IBS)?

What is Post-Infectious Irritable Bowel Syndrome (PI-IBS)?
Last post, we discussed how taking antibiotics for an infection or otherwise can affect the microbiome, but what about an infection triggering gut health issues? Well, that can actually happen too-- one example is post-infectious irritable bowel syndrome (PI-IBS).

PI-IBS accounts for up to 32% of cases of IBS. While the science is unclear on how this illness develops, the root cause is acute gastroenteritis (inflammation of the stomach and gut due to a bug that can cause infection) that triggers IBS symptoms. Acute gastroenteritis is fairly common, so why doesn’t everyone acquire PI-IBS following an invasion of a microbe or virus into their gut? Scientists suspect that along with how the infection affects the gastrointestinal tract and microbiome, other factors could be involved: genetic risks, how severe the case of gastroenteritis is, underlying psychological disorders, sex (females are more susceptible), and age (younger people are more susceptible). (1)

PI-IBS is linked to inflammation that is consistently there but not detectable by clinical tests, a porous intestinal tract, and changes in the balance of the gut microbiome. Abdominal pain, bloating, diarrhea, and other IBS symptoms can continue after the infection has passed because of the impact on the gastrointestinal tract and microbiome. As is the case with other types of IBS, PI-IBS cannot be diagnosed through a medical test, but rather through a process of elimination using tests that evaluate the presence of another condition, such as inflammatory bowel disease. (1) With more inflammation and pores in the intestinal wall (which is usually a strong barrier without holes), it’s thought that more immune cells such as T cells and mast cells--and possibly even hormonal cells containing serotonin--end up occupying layers of the intestinal lining. Altogether, these cell types release chemicals that can trigger a response in the enteric nervous system, which is the nervous system independently controlled by the gut (yes, the gut has a mind of its own!) (1). This can cause sensory nerves in the intestines to become overactive and thus lead to visceral hyperalgesia, which is a fancy way to say that your insides could be in more intense pain than normal (2). This might explain why people with IBS could have abdominal cramping after a meal, more amplified than the discomfort sometimes felt by normal digestion. This is caused by pressure on the walls of the intestines, which everyone experiences, but with so many nerves around that area to send info from the gut to the brain, it’s possible for the nerves to be overly stimulated and send pain signals when dealing with IBS.

While there still is no distinct cure for PI-IBS, symptoms may go down with time. One of the largest studies to date on PI-IBS showed that among Canadian patients with this condition, 31% still had symptoms of IBS after 2 years, 23% after 4 years, and 17% after 6 years. So while not everyone feels better immediately or after some time, most people in this study seem to as time progresses. However, the research must continue on this subject in order to figure out the mechanisms behind this condition and other functional gastrointestinal disorders. This will help determine better treatment approaches. (1)

Now that you’re armed with some more information, and aware of the gaps in research that remain, try to advocate for yourself if you think you may be dealing with PI-IBS! Remember, you’re not alone in this journey. Here’s some stories from others who’ve shared their experiences with PI-IBS:
If you want to take it one step further in your self-advocacy journey and learn more about your gut health on your own terms, try Injoy’s microbiome test kit and health app. This can provide informative insights into your gut microbiome health and provide clear, actionable recommendations on how to improve it.

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  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2721231/
  2. https://pubmed.ncbi.nlm.nih.gov/19300138/
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