The science behind “Crazy Cat Ladies,” and why kitties are taking over YouTube
Are you a cat or dog person?
This question is more than just a conversational icebreaker, as the answer may determine in part whether or not you’re more likely to have mental illness, get in a car accident, hoard things, and/or succeed in business.
These seemingly unrelated phenomena have something in common: a very clever cat-dependent parasite by the name of Toxoplasma gondii (T. gondii) that might just have the powers of mind control.
The life cycle of T. gondii and mouse mind control
Although the parasite can multiply in many hosts – humans included – it can only reproduce sexually in the intestines of cats. The oocytes, or offspring, of the parasite are then shed in cat feces. In fact, a single cat can shed up to 100 million oocytes!
Toxoplasmosis has been most thoroughly studied in rodents, species that for obvious reasons have a deep-seated, innate fear of cats. When rodents are infected with toxo, however, a strange thing happens: they stop fearing felines. In fact, they appear to be attracted to them, displaying more reckless behavior and slower reaction times in the face of danger.
This is wonderful news for cats, who now have dinner delivered to them, with minimal sleuthing, hunting, or pouncing required. When a cat consumes a toxo-infected mouse, more toxo cysts make their way to the cat’s intestines, where they can once again sexually reproduce, completing the cycle. (Cue music: Circle of Life, from the Lion King)
Toxo can affect such primal emotions as fear, anxiety and sexual arousal by increasing dopamine levels.
How does toxo make a timid little mouse prance into the jaws of its primary predator? It’s been suggested that the parasites invade the animal’s white blood cells and from there travel to the brain, where they override the mouse’s innate fear of predators and amplify aggression and novelty-seeking behavior by enhancing the neurotransmitter dopamine. Toxo can thus affect such primal emotions as fear, anxiety, and sexual arousal by increasing dopamine levels.
Toxoplasmosis-related diseases in humans
As in rodents, toxo can alter the behavior of humans. It’s been shown to slow reaction times and decrease concentration, which may explain why those involved in traffic accidents have been shown to be three times more likely to be infected with toxoplasmosis than others.
Those involved in traffic accidents have been shown to be three times more likely to be infected with toxoplasmosis than others.
Through its influence on personality and risk-taking behavior, toxo may also be associated with some serious mental health conditions, such as schizophrenia, bipolar, obsessive-compulsive disorder (OCD), and death by suicide.,
Toxoplasmosis and entrepreneurship
Increased aggression and risk-taking behavior has it upsides, however: toxo may play a surprisingly positive role in new business ventures.
The hormonal and neurological changes associated with toxo infection have the potential to enhance impulsive, reward seeking, and risk-taking behaviors. Toxo infection may thus amplify one’s ambition, their pursuit of material possessions, and their connection to self-achievement. Characteristics, in other words, associated with entrepreneurial activity.
Toxo infection may thus amplify one’s ambition, their pursuit of material possessions, and their connection to self-achievement. Characteristics, in other words, associated with entrepreneurial activity.
A recent paper in the Royal Society Journal explores the association between infection and entrepreneurial activity, finding that of the 1,495 students surveyed, those who tested positive for T. gondii exposure were more likely to major in business. The researchers also found that T. gondii-positive professionals attending entrepreneurship events were more likely to have started their own business than the other attendees.
But I don’t eat kitty litter!
Even though most (hopefully all!) of us aren’t eating cat waste, we can still contract toxo by playing in sandboxes and cleaning out kitty litter boxes. We can also unknowingly ingest toxo oocytes from contaminated water, unwashed produce, or the under-cooked meat of animals prone to toxo infection (such as pigs). For this reason, it’s very important to drink clean, filtered water, to wash produce, and to thoroughly cook all pork products prior to consumption.
Toxo sometimes causes vague flu-like symptoms, but more commonly has no observable symptoms and thus usually goes undiagnosed. One noteworthy exception to this, however, is in the case of pregnant women, in whom toxo can sometimes cause miscarriage or stillbirth. The infection may also damage the unborn fetus’ brain or eyes. In addition to following the other precautions explained above, pregnant women are also advised to avoid contact with kitty litter entirely.,
Why we still love cats
Despite the risks associated with toxo, many people still adore cats. Like the toxo-infected rats that find themselves attracted to felines, are those of us serving as hosts to the parasite more likely to love cats and keep them as pets? The question is being researched.
There’s also some thought that toxo infection may be linked to hoarding behavior (such as hoarding nine cats?), though that theory too is still under investigation.
What is clear, however, is that whether you’re a budding entrepreneur, somebody living with bipolar disorder, or a friendly cat lady, you may very well have a protozoan parasite by the name of Toxoplasmosis gondii pulling your strings. And you are not alone: it’s estimated that over 2 billion people worldwide are affected with toxo.
Could that be why cat videos have taken over YouTube? Quite possibly.
Click here to see References
 de Roode J. Is there a disease that makes us love cats? [Internet] TEDEd. [cited 3 December 2018]. Available from: https://ed.ted.com/lessons/is-there-a-disease-that-makes-us-love-cats-jaap-de-roode
 Zimmer C. EVOLUTION: Parasites make scaredy-rats foolhardy. Science. 2000 Jul 28;289(5479):525b-7b.
 Flegr J. How and why Toxoplasma makes us crazy. Trends Parasitol. 2013 Apr;29(4):156-63.
 de Barros JLVM, et al. Is there any association between Toxoplasma gondii infection and bipolar disorder? A systematic review and meta-analysis. J Affect Disord. 2017 Feb;209:59-65.
 Johnson SK, et al. Risky business: linking Toxoplasma gondii infection and entrepreneurship behaviours across individuals and countries. Proc. Biol. Soc. 2018 July 25;285(1883):20180822.
 Maldonado YA, Read JS. Diagnosis, treatment, and prevention of congenital toxoplasmosis in the United States. Pediatrics. 2017 Feb;139(2).pii:e20163860.
 Hampton MM. Congenital toxoplasmosis: a review. Neonatal Netw. 2015;34(5):274-8.
 Royall DR. Toxoplamosis and hoarding [Internet]. Grantome;2007 [cited 3 December 2018]. Available from: http://grantome.com/grant/NIH/M01-RR001346-26-6962