May 11, 2012
1 min read

Norovirus gastroenteritis may lead to post-infectious IBS

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Patients with viral gastroenteritis were more likely to develop post-infectious irritable bowel syndrome than controls in a recent prospective, population-based study.

Researchers administered questionnaires to residents of San Felice del Benaco, Italy, near Lake Garda, 1 month after a summer 2009 outbreak of viral gastroenteritis caused by Norovirus contamination of drinking water. Using these answers as a baseline, a follow-up questionnaire was sent to responders 3 and 6 months later, as well as to a control group 6 months after the outbreak. The questions were designed to measure gastroenteritis (GE) according to the Italian version of the Gastrointestinal Symptom Rating Scale (GSRS). After 12 months, a health assistant interviewed all participants to determine the presence of post-infectious irritable bowel syndrome (PI-IBS).

Of 348 patients who responded to the baseline questions, 69.5% of patients reported moderate to severe nausea, 59.5% vomiting and 77% diarrhea lasting two days or more. Fever was experienced by 49.5% of participants, and 19.3% reported weight loss, at an average of 3 kg.

After six months, 186 participants and 168 evaluable controls returned follow-up surveys. Investigators observed a significant difference in the frequency of GSRS scores at 4 or greater between patients and controls for symptoms including abdominal pain (OR=2.33; 95% CI, 1.12-4.89), diarrhea (OR=2.21; 95% CI, 0.83-5.9) and constipation (OR=2.55; 95% CI, 1.22-5.3), among others.

New IBS was diagnosed in 40 patients at the 12-month follow-up, compared with three patients in the control group (OR=11.40; 95% CI, 3.44-37.82), including four cases with constipation, seven with diarrhea, 16 with mixed symptoms and 13 unsubtyped cases. High GSRS score prevalence in the patient group compared with controls also was significantly greater across all dimensions at 12 months, and scores were significantly higher at all follow-up points among patients with PI-IBS compared with those without.

“Our study shows that PI-IBS frequently occurs after a viral GE as already known to occur after bacterial GE,” the researchers wrote. “In the case of Norovius infection, gastrointestinal symptoms persist over a period of at least 12 months from the acute illness in over 10% of patients. Further investigations should involve assessment of the role of genetic susceptibility to PI-IBS among our patients.”