Self-Motivation
David Goggins
Former Navy Seal
Career Development
Bryan Cranston
Actor
Critical Thinking
Liv Boeree
International Poker Champion
Emotional Intelligence
Amaryllis Fox
Former CIA Clandestine Operative
Management
Chris Hadfield
Retired Canadian Astronaut & Author
Learn
from the world's big
thinkers
Start Learning

One Third of Humanity May Host a Mind-Altering Parasite

Humans can contract the parasite by ingesting anything contaminated with cat feces. 

This article originally appeared in the Newton blog at RealClearScience. You can read the original here


In the opening scenes of Star Trek II: The Wrath of Khan, two Starfleet officers find themselves in quite a perilous situation. Captured by a group of renegades bent on revenge against Captain James T. Kirk, the duo is forced to host slimy, grotesque parasitic worms that crawl into their ears and roost in their brains. There, the parasites exert control over the two officers, bending their minds to the will of the renegades. 

To the best of our knowledge, insidious parasites like these only exist in science fiction. However, there is an organism on Earth -- a single-celled protozoan to be specific -- that bears a striking resemblance. And alarmingly, it may infest as much as a third of humanity (including 45% of the French)!


That parasite is Toxoplasma gondii. Commonly found in domestic cats, it sexually reproduces only within feline intestines. Humans can contract the parasite by ingesting anything contaminated with cat feces. Once infected, individuals may succumb to mild, flu-like symptoms for a couple weeks, but little more. Often no symptoms manifest at all. The parasite's apparent harmless nature cloaks its presence. Soon after finding its way into a human host, it weasels its way into the brain. There, "sheltered from the full fury of the immune system," it can remain in what's called a tissue cyst for decades, not reproducing, just persisting. But in this form, researchers are finding that it can produce some subtle and startling changes in the host's behavior.

Biologist Jaroslav Flegr, one of the leading researchers on T. gondii has discerned some very peculiar findings when comparing people with the infection to those without it. Kathleen Mcauliffe reported on this last year in The Atlantic:

...males who had the parasite were more introverted, suspicious, oblivious to other people's opinions of them, and inclined to disregard rules. Infected women, on the other hand, presented in exactly the opposite way: they were more outgoing, trusting, image-conscious, and rule-abiding than uninfected women.

Additionally, people infected with T. gondii display slightly impaired motor skills, undertake more risks, and get into more automotive accidents. Furthermore, 38 studies have linked the parasite with schizophrenia, a fact which fascinates neurologist and Yale assistant professor Steven Novella.

"Some drugs which are typically used to treat schizophrenia actually have anti-toxo effects," Novella said on a recent episode of The Skeptic's Guide to the Universe. "So they may work because they're actually counteracting toxoplasma, itself." 

How T. gondii subtly reprograms the brain is still not well understood. Studying the parasite outside of the body, researchers have found that it profoundly affects gene expression in host cells, as well as molecules involved in signal transduction pathways. If neurons in the brain are influenced in the same manner, that could possibly give rise to the behavior-altering effects.

Worldwide, as many as 1 in 3 people have T. gondii in their brains. Scary, I know. But hold off on any urges to cull the cat population. Indoor cats pose little to no threat to their owners, and the prevalence of infection is only about 1 in 10 in the United States (and currently declining). However, that's still a significant amount, a preponderance that makes you wonder how much of an effect these microscopic, mind-altering parasites really have on human interactions and everyday life as we know it.

 

(Image: Toxoplasmosis via Shutterstock)

Live on Tuesday | Personal finance in the COVID-19 era

Sallie Krawcheck and Bob Kulhan will be talking money, jobs, and how the pandemic will disproportionally affect women's finances.

NASA to add 'space hotel' to ISS, in privatization push

Got $55 million lying around? If so, you might be able to score a spot aboard the International Space Station starting 2024.

Image: Axiom Space
Politics & Current Affairs
  • NASA awarded a contract to startup Axiom Space to attach a "habitable commercial module" to the International Space Station.
  • The project will also include a research and manufacturing module.
  • The move is a major step in NASA's years-long push to privatize.
Keep reading Show less

Why is everyone so selfish? Science explains

The coronavirus pandemic has brought out the perception of selfishness among many.

Credit: Adobe Stock, Olivier Le Moal.
Personal Growth
  • Selfish behavior has been analyzed by philosophers and psychologists for centuries.
  • New research shows people may be wired for altruistic behavior and get more benefits from it.
  • Crisis times tend to increase self-centered acts.
Keep reading Show less

How Hemingway felt about fatherhood

Parenting could be a distraction from what mattered most to him: his writing.

Ernest Hemingway Holding His Son 1927 (Wikimedia Commons)
Culture & Religion

Ernest Hemingway was affectionately called “Papa," but what kind of dad was he?

Keep reading Show less
Videos

The biology of aliens: How much do we know?

Hollywood has created an idea of aliens that doesn't match the science.

Scroll down to load more…
Quantcast