Cyclospora had quite the summer.
The parasite was linked to an outbreak involving iceberg lettuce that sickened people with a particularly miserable symptom: watery, explosive diarrhea.
For anyone who got sick, the good news is that cyclospora infections can be treated. But foodborne illnesses don’t always run dry when the diarrhea does.
The CDC estimates that 48 million people get food poisoning every year. Meanwhile, thousands of people fell ill this summer amid a steady stream of recalls and outbreaks.
Norovirus — commonly known as the stomach bug — causes more foodborne illness than any other germ. Salmonella, the deadliest foodborne germ, was linked to a slew of everyday groceries, including jalapeños, blueberries, mangoes and even granola marketed to breastfeeding moms.
For many people, the misery is temporary, with food poisoning typically resolving within in a few hours for mild cases and up to a week or longer for severe bacterial infections
But sometimes, a bout of food poisoning can trigger post-infectious irritable bowel syndrome (PI-IBS), a chronic condition that can keep people dealing with abdominal pain, diarrhea, bloating and other symptoms long after the original illness has disappeared.
A 2024 review of 28,170 people across 47 studies found that 14.5% of people develop PI-IBS after acute gastroenteritis, a type of illness that includes food poisoning.
Food poisoning can trigger inflammation in the gastrointestinal tract, affecting the way the gut moves and disrupting its lining. The infection can also alter the gut microbiome, potentially setting the stage for symptoms that persist after the infection itself has cleared.
The condition is characterized by abdominal pain or discomfort and changes in bowel habits, which can mean diarrhea, constipation or changes in stool consistency or simply needing to use the bathroom more (or less) often.
People may also experience bloating, gas, a feeling they haven’t emptied their bowels and a sudden, urgent need to find a bathroom.
And the type of infection matters, too.
Food poisoning caused by bacteria is associated with a higher risk of PI-IBS than illness caused by viruses, while waterborne parasites such as Cyclospora can also trigger the syndrome.
Researchers aren’t clear how food poisoning can lead to PI-IBS, but the immune system appears to play a major role.
Campylobacter — the second most common cause of food poisoning in the US — offers one clue as to what may be happening. The bacteria carries a protein that can resemble vinculin, another protein involved in the movement of the gut. The immune system can mistake the two for each other and produce antibodies that attack vinculin, potentially interfering with normal gut movement.
That disruption can contribute to small intestinal bacterial overgrowth, or SIBO, which can cause symptoms that closely resemble those of IBS.
Fortunately, developing PI-IBS doesn’t necessarily mean you’ll be stuck with it forever.
Several treatments can help manage symptoms, including peppermint oil, gut-specific antibiotics such as Rifaximin, antidepressants, constipation medications and other IBS-specific drugs such as Alosetron and Tegaserod.
For people who also have SIBO, additional treatment may include glutamine supplements and an elemental diet, using a nutrient-rich powder mixed with water as a meal replacement to starve the small bowel bacteria while still nourishing the body.
About 50% of patients recover from PI-IBS without specific treatment, as the condition can resolve on its own, though recovery can take several months to to several years.
Some people are more likely to develop PI-IBS than others.
Those at higher risk include women, people 60 and younger, people with mental health conditions such as depression and anxiety and those who didn’t vomit during their foodborne illness or experienced longer lasting diarrhea.
