Are parasitic worms our friends or our foes?

When asked to think about parasitic worms, most people will cringe and screw up their faces in disgust.

When asked to think about parasitic worms, most people will cringe and screw up their faces in disgust. Squeamish or not, it is a challenge to imagine a worm-like creature that dwells in your insides as something positive. Believe it or not, growing up with parasitic worms could actually benefit you in later life, as long as the worm burden is small and doesn’t cause disease in itself. 

 

It has been known for a while that the presence of parasites in the body can have a positive effect on the host’s immune system. Often, when the body is not subject to pressures that it is evolutionarily used to, it can begin to attack its own tissues and sometimes whole organs to cause conditions like eczema, asthma and Type 1 diabetes.

 

These are autoimmune diseases, which are causes by an abnormal response to the person’s own cells. There are over eighty different conditions identified. 

 

 

Of course, parasitic worms can be incredibly dangerous. I’m not saying they’re the magical cure to all autoimmune diseases, because many cause some pretty nasty things themselves, even death. Onchocerciasis, more commonly known as river blindness, is a disease caused by infection with the parasitic worm Onchocerca volvulus. It is most common in sub-Saharan Africa and spread through the bites of black flies. 

 

The adult worm stays in the skin and forms nodules, while the microfilariae (minute larvae of the worm) can spread around the body and cause dangerous inflammatory responses. A debilitating skin condition can form which causes extremely severe itching so bad that sufferers are often unable to work, or the microfilariae can move to the eyes and cause blindness. 

 

Another rather nasty worm is the nematode parasite Baylisascaris procyonis which causes Baylisascariasis in humans and is carried by racoons. It is an important emerging disease in the USA, where racoons often live and scavenge around human habitation.

 

To cause human infection, infective eggs of the worm must be accidentally ingested, where they enter the bloodstream and are carried around the body and migrate within the major organs.

 

It may appear inconceivable for such a thing to happen, but consider a young child’s sandpit and the habit they have of putting things into their mouths. Suddenly it doesn’t seem so ridiculous. 

 

In the worst of cases, B. procyonis can enter the brain and cause damage that is irreversible, and sometimes even fatal. Diagnosis is also very difficult as the association with nematodes is hardly ever made in time, and symptoms are similar to those of epilepsy or meningitis. 

 

 

So, worms are obviously not always our friends. But what if we could use them to our advantage? And no, I’m not talking about the so-called ‘tapeworm diet pills’ that crop up every now and then on the internet, where the swallowed worm supposedly helps one lose weight by sucking up all the food that they eat. It doesn’t work like that I’m afraid.

 

Not only is a single tapeworm too ineffectual to make the slightest bit of difference in a person’s weight, but often these miracle worm pills contain the parasites of pigs or cows, rather than humans. 

 

More disturbingly, if they aren’t a natural parasite of humans, then your wormy weight-loss friend can end up in ectopic sites in the body, i.e.: the wrong place. Remember what happened with the raccoon worm? It’s a similar thing, and cysts can develop in the liver and other organs, even the brain.

 

These can be tricky to remove too and cause no end of problems. 

 

 

Back to their potential advantages (there are some, I promise!) It has been shown that those growing up with parasites, particularly helminth worms, can be at an advantage when it comes to the development of autoimmune diseases. In African countries, parasitic diseases are incredibly common, but the prevalence of autoimmune disease is very low.

 

The opposite is true for the UK and the US which have ridiculously high numbers of cases of inflammatory bowel diseases, multiple sclerosis and other autoimmune diseases but parasites are rare. 

 

Researchers in Australia may be on the right road to getting to the bottom of why this is. Scientists at Monash University have successfully identified the peptides from parasitic worms that suppress the body’s immune response. This could potentially pave the way for a new drug to relieve sufferers from the symptoms of autoimmune diseases, or perhaps even prevent them from occurring in the first place. 

 

This particular peptide discovery is important because of course nobody wants to swallow an entire worm. We don’t trust them that much yet. It also means that researchers are getting to the bottom of what exactly can stop the body attacking itself and the lives of many people may be about to change for the better.

 

Parasitic worms might not be our best friends just yet, but they might just be helping us out enough to change our minds in the near future.