While this column normally focuses on space topics, I’m going to take a brief detour to discuss some new science that’s been discovered on the unsettling subject of parasites.
When parasites get inside of creatures, they don’t just chill there. They have all kinds of weird and creepy ways of manipulating their hosts into doing what’s in the best interest of the parasite. The Toxoplasma gondii parasite is a single-celled organism that wants to live in the intestines of a cat. Sometimes, however, it finds itself inside the body of a rat instead. How does it solve this problem? It lives in the rat’s brain and changes it’s behavior to—among other things—make the rat attracted to the smell of cats, leading it to get eaten.
Toxoplasma, sometimes called Toxo, also affects about 1/3 of the world’s human population. It was until recently thought to be symptomless, but studies are showing that Toxo may also have some effect on the human brain as well. Read past the break to learn how to use Toxo—or an organism like it—to set up conflict in your campaign setting.
Parasites and How They Work
Toxoplasma organisms under a microscope.
Toxo is not the only parasite—or even the only disease—that can affect the behavior of an infected host. Parasites don’t just want to live in an organism. They want to create specific conditions that will allow them to reproduce. They can lie dormant until conditions are right and then strike.
One species of parasite wants to be inside of a sheep, so it infects an ant and programs it to climb to the top of a blade of grass and stay there all night. If the sheep doesn’t eat it during this time, it tells the ant to climb down so that it doesn’t get burnt by the sun. The ant goes about its business for the rest of the day, and then at night, the parasite orders it to climb to the top of the grass again.
There’s a fungus in the Amazon called Ophiocordyceps that affects a different species of ant. In this case, it orders the ant to climb to a specific height on a tree at noon and find a location facing North West. It orders the ant to clamp down on a leaf, and then destroys all of the mitochondria in the ant’s body, leaving the ant unable to move. Within six hours, the ant dies and the fungus sprouts from its head. The fungus then releases spores that infect new ants.
Even influenza has been shown to change the behavior of the infected. After receiving a flu shot, test subjects felt an increased desire to spend time with other people—thereby transmitting the disease.
So microbes. They’re crazy, right?
What about Toxoplasma?
This rat thinks it’s making new friends.
Toxoplasma wants to be in the digestive system of a cat, but sometimes it can get into other mammals by mistake, such as livestock, rats or people. It can even effect birds. Toxo can survive for about a year in soil (or sewage), so it has plenty of time to be picked up by a host. When Toxo gets into the wrong kind of host mammal, it will form cysts in that animal’s brain and around their organs and try to alter the host animal’s behavior.
Here are some things that the Toxo parasite does to Rats and/or people:
- Toxo creates something in rats called “Fatal Feline Attraction” that causes the rats to seek out cats instead of run from them.
- While the behavior of rats with Toxo is mostly the same as rats without Toxo (other than the issue of being attracted to cats), mice that are affected with Toxo have a high mortality rate and engage in bizarre behaviors such as running around in circles while tilting their head to the side.
- Toxo increases risky behavior and impairs motor skills in both rats and humans. People with a Toxo infection are more likely to get into car accidents.
- Toxo can be passed down from mother to child during pregnancy.
- Toxo increases the amount of dopamine in the brains of rats. This is what changes the fear/pleasure response and increases the risky behavior.
- Toxo increases the amount of dopamine in the brains of humans, too. Humans with Toxo are more frequently affected with mental illnesses such as anxiety or depression than the general population.
- There is a link between schizophrenia and Toxoplasma. This has something to do with Toxo’s ability to produce dopamine. It is believed that Toxo has some role in inducing schizophrenia in people with genetic risk factors or worsening schizophrenia in people who already have it. Medications that work against schizophrenia also affect Toxo. Not everyone with Toxo has schizophrenia and Toxo is not responsible for all cases of schizophrenia.
- Some scientists suspect that some cases of brain inflammation and brain cancers can be caused by Toxo but there is no evidence yet to support the claim.
Using Toxo and Other Parasites in Your Game
This is not toxo. This is a hookworm. I put it here because I didn’t think you were having enough nightmares. You’re welcome.
Let’s go straight to the most obvious scenario: A parasite like Toxo silently infects most of the world’s population, then mutates to adapt to human physiology, causing the zombie apocalypse. The mutation could be natural or caused by a man-made trigger.
Toxo could be an ancient alien weapon waiting for a signal from its creators. Once the aliens arrive to take over the planet, they trigger the true effects of the Toxo parasite to either incapacitate or weaponize 1/3 of the earth’s population. Maybe it instructs the victims to cluster together to make them easier to harvest or kill.
An opportunistic parasite could rain down on the world from a Rogue Planet sweeping through the solar system. It could be programed to try to get humans into space. Perhaps it’s initially praised as a way to enhance humans by making them smarter—causing people to go out of their way to try to get themselves and their children infected. Later, when the debilitating side effects of the parasite are discovered, a debate emerges as to whether the benefits of hosting the parasite outweigh the cost. To complicate matters, any of the “brightest minds” who search for a cure (and are also infected), find the parasite actively thwarting their attempts.
A parasite like Toxo could be responsible for humans developing psychic powers. Perhaps these powers come with dangerous side effects.
A microorganism or parasite could be responsible a sudden spike in aggressive behavior or a sudden increase of people falling into comas.
In a far future setting, colonists from a particular planet may acquire a bizarre character traits caused by exposure to the environment. Perhaps they all develop a physical tick or suddenly belong to a cult-like religion. The interstellar federation needs to prevent this parasite from spreading to the rest of the federation through the cult’s “evangelists.”
Parasites are pretty freaky creatures. The idea of strange creature lurking silently inside of you, waiting to betray its traitorous intentions can instantly ramp up the fear and menace in your game.
Have you ever used something like Toxo in a campaign setting? How about another parasite? Is it something you’d like to try in the future? Leave a comment and tell me all about it!
