Wednesday, February 5, 2014

Parasite Manipulation of the Host

Mind Control Everywhere!

Being able to have mind control seem like a sophisticated power that many would like to have. In Vampire Diaries, the evil vampire, Damon, is known to use this type of techniques on others such as Jeremy. You can also find this type of behavior in cartoons such as SpongeBob Squarepants when Plankton takes over SpongeBob’s mind to try to get the secret formula for the crabby patty. Unfortunately, being able to control something or someone’s mind is very unrealistic – but not for certain parasites. This unique characteristic has given the parasites the upper hand when it comes to the evolution of parasites vs. host. Getting a host to do whatever, or go wherever is a necessity in order to get to their next life cycle. (1)

How and Why Does This Happen?

When the parasite has finally encounter the intermediate host and is able to survive the host immune system, the next step for the parasite is to somehow manage its way to get to its definitive host. It has been report by Poulin that usually the intermediate host is not the average meal that the definitive host would eat which is why this could become tricky for the parasite (2). Thanks to the product of natural selection, genetic manipulations, which is manipulation of an organism’s genome that has influenced another organism’s phenotype, is the reason of how parasites has the advantage over their host. Being capable of changing its phenotype is also one of the main reasons why parasites modify the host behavior. There are actually more other reasons to answer why specifically the parasite changes the host behavior. Another reason, probably the most obviously, is because it helps the parasite fulfill its life cycle. The last reason for why the parasite changes the host’s behavior is because it inherited this specific trait from an ancestor and it is now just embedded in the way it functions. (3)

Zombie Snails

Snails are one of the many organisms that are the victim of a parasite that is able to have mind control over them once infected. This specific parasite that is responsible is the Leucochloridium worm. This worm is able to get inside the snails eye stocks and also a result makes the eyes look more like yummy caterpillars to worms. Most importantly, the Leucochloridium worm takes over the snail’s brain. The way they are sufficient in doing so is by having the snail work its way up in plane view site so that predators, in this case birds, are quickly able to spot the infected snail. This process in the end makes for a happy parasite family that is now it able to achieve its finally life cycle in the birds stomach. The way that the cycle is able to start over again is that the snails eat the infected birds feces. Already you can quickly observe and apply the reasons to why this particular parasite wanted to have the snail behave differently. It was capable of changing the snails phenotype which in return helped it successfully complete its life cycle by being able to enter into the birds digestive tract and lastly the mind – control is inherited so it can again go through the same life cycle each time using this trait so that it can strongly complete the life cycle with little to no problem. (4)


(1) The Art of Being A Parasite by Claude Combes





  1. Here's another interesting case of mind control in nature! It's about parasitic fungi of the genus Cordyceps and their unsuspecting ant victims.

  2. The references you made work really well with your topic. This post was easy to follow and understand which also made it interesting. The idea of mind control by parasites sounds crazy but that is what it is, the parasite is modifying the behavior of its host to get to its destination. This is just another way some parasites control their hosts in order to be successful and reproduce. Mind control sounds like an efficient way for a parasite to get to its definitive host and continue surviving and reproducing.

  3. I found your post to be very informative and you had some really good examples. I am still surprised how horrible it must be for a parasite to control an organism against its will. For example, Toxoplasmosis infected mice are more attracted to cat urine, making them more prone to get eaten by cats. Normally this is the last thing a mice would want to do, but under the influence of this parasite everything changes.