In December of 2010, a fire broke out in an apartment building in Belgium. As firefighters struggled to contain the blaze, they used sewer water to fight the fire. In the process, they accidentally connected that water source to the main community water supply. Sewer water, containing among other things infectious organisms like norovirus, Giardia and Campylobacter, was pumped into the drinking water pipes and spread quickly throughout the water supply of this town of about 18.000 people. Within 24 hours, a lot of people were seeking help for acute gastrointestinal illness, and it was clear that a major outbreak of GI infection had occurred.
It is now well known from many studies that a subset of people who become sick from food poisoning or contaminated water develop chronic functional gastrointestinal disorders as a result – irritable bowel syndrome (IBS) and functional dyspepsia (FD). Researchers are always looking for natural experiments or accidents like this water contamination to study how infections turn into chronic gastrointestinal disorders and who develops such problems and who does not. In this case Belgian gastroenterology researchers in Leuven, which happens to be a mere half-hour drive from where this outbreak occurred, were quick to descend upon the unfortunate town in order to get baseline data from the local residents and start following their health over time.
Today at Digestive Disease Week 2013 in Orlando, those researchers presented their findings of their study of the long-term effects of this massive but brief exposure to contaminated drinking water.
In the study, they asked all the residents of the affected town to complete questionnaires on gastrointestinal symptoms they had before, during and after outbreak, and also about their psychological symptoms and other characteristics. These questionnaires were completed 0-3 months after the outbreak. They also asked the subjects to complete such questionnaires again a year after the outbreak to evaluate the long-term effects on GI symptoms. A total of 1377 people completed the questionnaires, but data from children younger than eighteen and from all people who reported that they had GI symptoms consistent with IBS or functional dyspepsia before the outbreak were eliminated from analysis. This left 1028 questionnaire sets to be analyzed. It turned out that 30% of the subjects had become sick with infectious gastroenteritis within 2 weeks of the contamination. When those individuals were surveyed a year later, 15.6% of them were found to have IBS and 19% had functional dyspepsia, according to Rome III diagnostic criteria (remember, none of these people had these disorders before the gastroenteritis outbreak). Interestingly, a fairly significant number of individuals in the other 70% of the survey sample — the ones who were exposed to the contaminated water as well but did not have immediate GI problems — were also found to have IBS (6.5%) and FD (12%) after a year (much higher rates of new incidence of these disorders than one would typically expect in the general population). The investigators found that of all the individual characteristics that they assessed in the study, being of younger age and having higher somatization score at the time of the outbreak (that is, already having a lot of non-gastrointestinal body symptoms) were factors that predicted greater likelihood of developing long-term IBS or functional dyspepsia symptoms after exposure to the contamination. Having diarrhea symptoms for several days after exposure was also a risk factor for meeting diagnostic criteria for IBS a year later.
This study is a very nice addition to the research knowledge base on post-infectious IBS and post-infectious functional dyspepsia. I particularly liked that the researchers studied functional dyspepsia and IBS in parallel, for this allows direct comparison of the relative risk of developing each of those disorders long-term from infection. Another valuable aspect of the study is that the contamination here was a broad cocktail of common infectious organisms that can cause GI problems. This makes the findings more generalizable, for it shows us the substantial long-term health risk associated with drinking unclean water for even a relatively short period of time. The risk factors identified as causing people to be more likely to develop long-term post-infectious gastrointestinal diseases in this research are the same as have been found in multiple previous studies1 so this work confirms once again that younger adults are more vulnerable, and that not recovering quickly from the initial gastroenteritis bowel distress and being prone to having a lot of body symptoms are all factors make people more likely to develop chronic functonal GI disorders from infection.
I found two additional aspects of the findings from this study particularly interesting: The first was to see that people can develop long-term functional GI disorders as a result of drinking contaminated water without having any acute GI symptoms soon after the exposure to clue you in that they have even been infected at all. And the second noteworthy observation was that exposure to water contamination mostly resulted in either IBS or functional dyspepsia a year later, but few people developed both disorders: There was only 17% overlap according to my conversation with the principal author, Sander van Wanrooij, at DDW today.
Su2031. Postinfectious Irritable Bowel Syndrome and Functional Dyspepsia Following an Outbreak of Tap Water Contamination. Sander van Wanrooij, Mira M. Wouters, Stephanie Mondelaers, Laura van Gerven, Annick de Vries, Pedro J. Gomez-Pinilla, Guy E. Boeckxstaen. University Hospital and University of Leuven, Belgium
1. Ghoshal UC, Ranjan P. Post-infectious irritable bowel syndrome: the past, the
present and the future. J Gastroenterol Hepatol. 2011 Apr;26 Suppl 3:94-101. doi:
10.1111/j.1440-1746.2011.06643.x. Review. PubMed PMID: 21443719.