Research published today in the journal Cell suggests that viruses known to target the central nervous system may also affect neurons of the digestive tract, causing intestinal blockages and abdominal pain.
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Abdominal pain is one of the most common ailments for which patients seek relief and is notoriously difficult to diagnose.
The nature and location of the pain can vary but is most commonly a consequence of a build-up of gas or food that is more difficult to digest.
In some patients, however, the abdominal pain is particularly severe and arises suddenly with no apparent cause. Furthermore, it can recur without warning, causing regular suffering and distress.
Researchers at Washington University School of Medicine think they may have uncovered a possible explanation.
During their study of West Nile virus in mice, they noticed that some of the infected mice showed evidence of intestinal blockage. The virus caused the intestines to expand and slow transit through the gut.
It was subsequently discovered that the virus infects neurons in the intestinal wall that are responsible for coordinating muscle contractions to move waste smoothly through the gut.
Immune cells then congregated at the site of the infection and killed the infected neurons to remove the virus. The loss of these neurons disrupted bowel movement causing intestinal blockages.
Similar findings were reported for other related viruses, such as Zika, Powassan and Kunjin viruses, that target the nervous system.
In theory, any virus with a propensity for infecting neurons could cause this kind of damage. This includes the relatively widespread enteroviruses and herpesviruses.
In contrast, the chikungunya virus, an unrelated virus that does not target neurons, did not cause bowel dysfunction in infected mice.
There are a number of people who are otherwise healthy who suddenly develop bowel motility problems, and we don't understand why.
But now we believe that one explanation could be that you can get a viral infection that results in your immune cells killing infected neurons in your gut. That might be why all of a sudden you can't move things along anymore."
Dr. Thaddeus S. Stappenbeck, Co-author
Although the digestive tracts of infected mice did recover after a couple of months, the symptoms flared when the mice were exposed to an unrelated virus or an immune stimulant.
This pattern reflects that observed in humans, where patients cycle through bouts of gastrointestinal distress and recovery.
These findings could potentially explain why some people experience recurrent, unpredictable bouts of abdominal pain and constipation.
Further investigation may lead to the development of new treatment strategies to prevent the recurrence of such symptoms.
It is even feasible that a vaccine could prevent chronic gut motility problems. Previously vaccination against enteroviruses had not been considered as it was thought that infections were self-limiting.