Does exposure to Mebendazole (Vermox) in childhood increase the risk of development of inflammatory bowel diseases?

What is Inflammatory Bowel Disease (IBD)?

Inflammatory bowel disease is the name given to a group of chronic inflammatory diseases involving the gastrointestinal system. The two main diseases are Ulcerative Colitis (UC), where there is involvement of the mucosal wall of the large intestine and Crohn’s Diseases (CD) which can involve all the different parts of the gastrointestinal tract as well as the different layers of the bowel wall.
These diseases have a variety of clinical manifestations, all the way from manifestations that are related to the gastrointestinal tract, including abdominal pain and bloody diarrhea as well as those that involve different body systems. In fact, they can involve any of the body’s systems.

What causes Inflammatory Bowel Disease?

The specific causes behind development of the disease are unknown but there are several risk factors that may attribute to their development.

What is the association between antibiotics to inflammatory bowel diseases and what is “The Hygiene Hypothesis”?

Wait a second, you are right. How are antibiotics related to this? Afterall, Mebendazole is not an antibiotic.
Well, the term ‘antibiotic’ is commonly used to refer to all the products that are used to treat different bacterial infections, but the correct term is ‘antimicrobials’, which means medications used to treat different pathogens.
Mebendazole (Vermox), for example, a medication used to treat worms, is an antimicrobial. And the concept behind antimicrobials is similar to the one behind antibiotics. Continue reading for a few more minutes. I am going to briefly discuss antibiotics that are more commonly used than Vermox and then we’ll get back to the worm talk.
Among the different theories behind the causes of IBD, there was an attempt to study the association between antibiotics and the development of these diseases, but the results were not clear-cut. Different studies found results that could be interpreted both ways, so it is difficult to draw any clear conclusions about the association. But at the basis behind this hypothesis sits “the hygiene hypothesis”. According to this hypothesis, decreasing exposure to infectious pathogens leads to an increase in the incidence of immune-mediated diseases. The idea is that exposure to these infections teaches the immune system which pathogens it should learn to protect itself from. Antibiotics, however, decrease the body’s exposure to such infectious pathogens and by doing so decrease the prevalence of different infectious diseases which also leads to a negative effect on the microbiome (the microbiome is the population of ‘good’ bacteria that inhabits our bodies and is found mainly in our intestines but also on other sites). The less exposure to and the less development of infections, the higher the chances that our immune system will get confused, lose its balance, and mistakenly attack the different systems in our body, and by doing so, aid in the development of different diseases.

What are worms and what are parasites?

When we talk about infectious pathogens, we are all familiar with viruses and bacteria, but the truth is that there are more members that belong to this big family, and these include parasites. Within the parasites group we also have worms. Their name – parasites – depicts their characteristic behaviour. They live inside their host (in our case it is our body), where they obtain optimal conditions for thriving.

How are parasites and worms related to “The Hygiene Hypothesis”?

Parasites are able to live inside our bodies, among other places, by using different mechanisms that create a certain balance against our immune system, which tends to respond to them but does not attack and kill them. This is where “the hygiene hypothesis” stems from and it is based on the idea that parasites are able to “calm” our immune system down and to prevent it from developing extreme responses to different stimulants. In turn, medications against parasites can bring about a decrease in the prevalence of such infections and hence a decrease in their protective effect over the immune system which is required when our system is exposed to other chemicals. And this theory actually serves as the basis behind the aim of the article, as you will see below.

How is age related to “the hygiene hypothesis”?

Another important factor that one must remember is age of exposure. We know that when it comes to food allergies, for example, the age of exposure to different foods plays a role in the development of a balanced immune system, that is able to deal with different allergens (I’d like to invite you all to read more about exposure to solid foods in babies in the link here). When it comes to exposure to infections and proper development of the immune system, we tend to believe that the first 5 years of life are the most important and play the most significant role.

So, what was the aim of this article?

The aim was to study the effect of treating children with mebendazole (or Vermox), and the risk of developing inflammatory bowel diseases in life.

Methods – the study was based on data extrapolated from population registries from Denmark. The researchers collected data from children born between 1995-2018 and checked to see who received Mebendazole prescriptions, the age for first exposure and whether or not members of the same household received it due to suspected cross-infection. This data was compared with Inflammatory Bowel Disease registries and the lists were divided based on age of diagnosis (prior to and after 16 years).
Results – this was a huge study, with very impressive long-term findings. About 1,520,290 (!) people were included, of which 615,794 participants had been previously exposed to mebendazole before the age of 18 and 348,934 had been exposed before the age of 5.
1,555 participants were eventually diagnosed with inflammatory bowel disease in childhood and 1,499 were diagnosed in adulthood. Following analysis, the results revealed that exposure to Mebendazole prior to the age of 5 (but after the age of 1.5 years) was associated with a 17% increased risk of developing IBD, specifically Ulcerative Colitis, in adulthood. No association was found between exposure and the development of disease in childhood. Also, there was no association between exposure after the age of 5 and the development of disease.
Discussion – this is the first study revealing such impressive results. Of note, Mebendazole is also used as treatment against other parasites, and not just the pinworm we’re all familiar with. Other medications from the same group were not studied in this research and we must also remind ourselves that when conducting such large studies, where data is gathered from registries, there tends to be an inherent bias related to the technique behind this type of data collection.
Why was there an association found for ulcerative colitis in adulthood, but not in childhood? Is it maybe because these are two different diseases with different risk factors? Or is it because of the longer exposure time that lapsed before the development of disease?
Another interesting question would be – and this is kind of similar to asking which came first: the chicken or the egg – whether the increase in prevalence of the disease today is related to the decrease in parasitic infections due to improved hygiene and cleanliness in our developed world, (similarly to “the hygiene hypothesis” idea”) or does the actual medication have a detrimental effect on the gastrointestinal tract?

So, what are our conclusions? Simply put, exposure to Mebendazole between the ages 1.5 and 5 years can be associated with an increased risk of development of ulcerative colitis in adulthood.

What is my take home message?

Exposure to different foods and chemicals at a young age, at different time-points, can play a significant role and have long-term effects on our lives.
And as I’ve already mentioned in the article that discusses exposure to antibiotics, when it is not necessary, then it really is unnecessary. And if your child does not need the antibiotic or antimicrobial, do not give it to them.
But then again, if your child has worms and you’ve seen them with your own eyes, or your suspicion is very high, give your kid Mebendazole – do not leave them to suffer.
And the fact that this article found an association between a medication and colitis certainly does not mean that anyone who has ever received Mebendazole will develop colitis. Keep things in proportion.
However, and I wrote this already in my post about worms too, many times parents like to give their children medication ‘just to be safe’ or because of a very slight suspicion, sometimes because their child itched their bum, once, the other day. In cases like these, think about this article before handing Vermox over to your kids.

All the best my friends.