Did you know that some parasitic worms can control our immune systems? You may have heard of them as tapeworms, flukes, nematodes or even as a supporting character in the game "Warframe" but these creatures may be a cure for diseases as nasty as they can cause! Let's look at...
- The Humble, Horrible Helminth: What are these worms?
- On a Biological Tightrope: How can they survive in our bodies?
- A Curious Consequence of Helminth Infection: Are there upsides to an infestation?
 |
| Helminth worms are particularly common in tropical conditions... (ralexchristy on Pixabay) |
The Humble, Horrible Helminth
Helminths are, when you get right down to it, a broad collection of parasitic worms. Their ranks contain tapeworms, nematodes and flukes - meaning that they are responsible for some incredibly nasty diseases.
These worms use a variety of methods to get into a host, but common vectors include consuming contaminated (usually by sewage) water or food, through being bitten by an infected insect or even by walking on infected soil.
Perhaps the biggest asset possessed by these worms is an ability to fool or manipulate the immune system of their host. Being able to do this allows the helminth to live inside the human body for years, when most other infections would have either been driven out... or killed us!
These worms use a variety of methods to get into a host, but common vectors include consuming contaminated (usually by sewage) water or food, through being bitten by an infected insect or even by walking on infected soil.
Perhaps the biggest asset possessed by these worms is an ability to fool or manipulate the immune system of their host. Being able to do this allows the helminth to live inside the human body for years, when most other infections would have either been driven out... or killed us!
On a Biological Tightrope
As I mentioned above, helminth worms survive inside humans by partially suppressing our immune system.
This is a risky venture for the worm - if they don't suppress the immune system enough, it will find and destroy them. Death can come in a number of ways - because helminths are usually too big to be engulfed by a white blood cell, the body sends out cells filled with a cocktail of lethal chemicals that can burst over the helminth and break it apart. The worm can also be crushed by tissue that it has inflamed!
On the flip side of the coin, the host will sicken and die to another diseases if a helminth suppresses the immune system too much - potentially leading to the death of the worm before it can reproduce. The sweet spot is somewhere in-between - suppress the immune system just enough that the worm can survive, while leaving the host mostly healthy.
There's also another factor that can help the worms survive - how costly it is for the human body to unleash a massive immune response. Producing loads of white blood cells and antibodies costs precious resources (not to mention the collateral damage these cells can do to the body.) If the worms don't become too much of a burden, they may not be worth the effort of removing them!
This is a risky venture for the worm - if they don't suppress the immune system enough, it will find and destroy them. Death can come in a number of ways - because helminths are usually too big to be engulfed by a white blood cell, the body sends out cells filled with a cocktail of lethal chemicals that can burst over the helminth and break it apart. The worm can also be crushed by tissue that it has inflamed!
On the flip side of the coin, the host will sicken and die to another diseases if a helminth suppresses the immune system too much - potentially leading to the death of the worm before it can reproduce. The sweet spot is somewhere in-between - suppress the immune system just enough that the worm can survive, while leaving the host mostly healthy.
There's also another factor that can help the worms survive - how costly it is for the human body to unleash a massive immune response. Producing loads of white blood cells and antibodies costs precious resources (not to mention the collateral damage these cells can do to the body.) If the worms don't become too much of a burden, they may not be worth the effort of removing them!
 |
| Helminth infection might actually suppress some allergies. (TomDansken on Pixabay) |
A Curious Consequence of Helminth Infection
Researchers believe that almost a third of humans are helminth hosts, with the majority of cases concentrated in tropical regions. Most infections are asymptomatic however, meaning that the sufferers may not even notice anything wrong.
Researchers have also noticed that these places have much lower rates of allergies and autoimmune diseases, both of which are caused by the immune system attacking when it shouldn't. Given that helminth parasites can gently "downgrade" the power of the human immune response, is it possible that they are providing an indirect benefit to their hosts?
The scientific community is certainly interested in that question, as several human trials have been carried out already. Researchers infected human volunteers with helminths and monitored the effect on their pre-existing conditions. While not every trial was a success, patients with multiple sclerosis showed minor improvements. More encouraging were the results for Crohn's disease and ulcerative colitis, with many patients showing a significant increase in health.
You might be wondering how willing people would be to get infected by parasitic worms as a treatment. Rather than infecting people, researchers hope to identify the chemical tricks used by the worms and reproduce them as a drug. Letting an uncontrolled helminth infestation run rampant through a patient is not a desirable outcome, since it will also weaken a patient's ability to fight bacteria, viruses and cancerous cells. It would also mean that the patient could infect other, healthy people - lawsuit, anyone?
Researchers have also noticed that these places have much lower rates of allergies and autoimmune diseases, both of which are caused by the immune system attacking when it shouldn't. Given that helminth parasites can gently "downgrade" the power of the human immune response, is it possible that they are providing an indirect benefit to their hosts?
The scientific community is certainly interested in that question, as several human trials have been carried out already. Researchers infected human volunteers with helminths and monitored the effect on their pre-existing conditions. While not every trial was a success, patients with multiple sclerosis showed minor improvements. More encouraging were the results for Crohn's disease and ulcerative colitis, with many patients showing a significant increase in health.
You might be wondering how willing people would be to get infected by parasitic worms as a treatment. Rather than infecting people, researchers hope to identify the chemical tricks used by the worms and reproduce them as a drug. Letting an uncontrolled helminth infestation run rampant through a patient is not a desirable outcome, since it will also weaken a patient's ability to fight bacteria, viruses and cancerous cells. It would also mean that the patient could infect other, healthy people - lawsuit, anyone?
Final Thoughts
While helminths may sound like they offer a solution to allergies and autoimmune disease (something a lot of people could really benefit from) we shouldn't forget that they are suppressing the immune system to do it. This can have a number of knock on effects, ranging from increased rates of malarial infection to preventing vaccines and medicines from working. To make matters even worse, the places where helminth infections are most common are the same places that need modern medicine the most.
Thanks for reading - you might also be interested in...
Thanks for reading - you might also be interested in...