Science of Love, Sex, and Babies

Can an infection have mind-control properties?

Posted in news, pregnancy by jenapincott on September 29, 2010

I try to be calm as the obstetrician draws my blood to test for toxoplasmosis.

Officially known as T. gondii, toxoplasmosis (or toxo) is a single-celled protozoa transmitted by exposure to cat excrement and by eating raw meat. We can also get it by gardening, eating unwashed fresh veggies and fruit, walking with bare feet on feces-rich soil.

My doctor tests all pregnant women for toxo, as do many doctors in Europe. Infection rates hover around 12 percent in the United States. In Brazil about 67 percent are infected (due to warm climate), in Hungary 59 percent, and in France about 45 percent (for the latter, blame all that steak tartare and pink lamb).

We’ve known for decades that toxo does weird things to the brain because rats infected with the parasite act a bit strange. By strange I mean they’re not only afraid of cat scents, they’re strangely aroused by them. And because they seek out cats, they’re often consumed, and in being consumed they infect the cats, completing toxo’s lifecycle. This is how the parasite perpetuates — by puppeteering. It manipulates rodents to sacrifice themselves to infect other cats and other rats, and so on.

Toxo may also invade and manipulate the human brain, which shares much of the same anatomy and neurotransmitters with rats — although mind control here is different (cats don’t usually eat humans, so there’s no evolutionary pressure on the parasite to tweak its effect on people). Paristologist Jaroslav Flegr of Charles University in Prague found that people with a latent infection tend to be more apprehensive, guilt-prone, self-doubting, and insecure. They have slower reaction times, especially if they also lack a certain blood protein, and three times as likely to get into traffic accidents due to impaired attention or reflexes. Infected women tend to be warmer-hearted, dutiful, moralistic, conforming, easy-going, persistent, and more outgoing and promiscuous. Infected men tend to be more jealous, rigid, slow-tempered, rule-flaunting, emotionally unstable, and impulsive.

Correlation is not causation, as scientists say when fascinating associations like this arise. But toxo may have an impact on personality and behavior because causes slight brain inflammation and alters its host’s levels of dopamine, the neurotransmitter associated with reward and anticipation (and also movement). The parasite does this by producing an enzyme called hydroxylase, which makes dopamine.

Dramatic as this sounds, most people are completely oblivious that toxo haunts their cells. Only pregnant women are commonly tested. And I’m one of them. Because I’m a hypochondriachal life-long cat owner who once worked on a farm, travels extensively, and doesn’t always scrub her veggies vigorously, I’m convinced I’ve been infected.

The nurse doesn’t think it’s an issue. “Not much happens if you’re positive,” she says, and shrugs. Her body language suggests it’s a silly test.

“Unless it’s a recent infection it doesn’t matter. We can tell by the antibodies if you’ve been infected in the last few months. If so, we give you antiparasitic drugs.”

Simple as that.

From a medical perspective, what she says is true. The risk to a fetus depends on the timing of infection and recent infection has the most disastrous consequences. If you happen to become infected with toxoplasmosis while pregnant, or soon before, the parasite or its toxins may cross over the placenta to infect your baby’s nervous system. Babies born to mothers infected in the first half of pregnancy often have shrunken or swollen brains and mental retardation. If infected in the second half, babies may not show symptoms at birth yet central nervous system problems may emerge years later. These babies are at a higher risk of developing schizophrenia — delusions, hallucinations — later in life, likely due to altered levels of dopamine triggered by the parasite.

The nice news is that if you’ve been infected for years before pregnancy you probably won’t pass toxo to your baby, nor will you likely have any obvious signs of infection (although cysts form in the brain). According to Dr. Flegr, only an active infection in the mom suggests a causal link between infection and her baby’s temperament. This is because your immune system usually keeps the parasite in check. But don’t think it’s completely asymptomatic.

In the past decade or so, studies have found that moms with dormant toxo infections have more sons (up to two boys for every girl), and those fetuses develop slightly more slowly than other babies. Perhaps there are other side effects that are undocumented.

Reading up on the science of prenatal infection I get reflective. Viruses, bacteria, and other parasites have always entered us — and some, such as our mitochondrial DNA (originally a bacterium), have become part of us and we can not live without them. Ancient viruses now exist deactivated or defanged in our DNA (in fact, genes from the placenta are thought to be a legacy of ancient viruses) Some viruses may be reactivated, like half-cured villains released from prison, and are thought to be a cause of cancer. Some invaders, initially dangerous, have converted to communalism, such as the thousands of good-guy varieties of healthy gut bacterial that make digestion possible. Strange but true: there are more bacterial than human genes in our bodies.

In a way, pregnancy has made me less fixed on the notion that my self is a singular identity over which I have total control. The fetus is me but not me, and she has changed me in ways I can’t yet fathom. The line between self and other is getting fuzzier.

But as philosophical as I get about self and other, me and microbe, my heart still races when I call the nurse to read my test results.

Negative for toxoplasmosis.

I’m relieved. Truth is, the only parasite I really don’t mind carrying is the baby.

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28 Responses

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  1. The Simple Life of a Country Man's Wife said, on September 30, 2010 at 9:25 am

    Phew! That was a relief to hear the results. I have heard of toxo but just learned quite a bit more … thanks for posting!

  2. ricarpa said, on September 30, 2010 at 9:38 am

    looks great and interesting…

  3. The Gates of Lodore said, on September 30, 2010 at 10:50 am

    Wow, I don’t think I have ever heard of this. But the real strange thing is that just last night as I was falling asleep, I wondered if there was a virus that specifically targeted brain function and thoughts. And this morning I woke up, and saw this blog.

  4. CrystalSpins said, on September 30, 2010 at 11:28 am

    “the only parasite I really don’t mind carrying is the baby.”

    Ha hah ahah ha ha!

    Love it.


  5. She.Is.Just.A.Rat said, on September 30, 2010 at 11:40 am

    Appreciate the morning science lesson. I was not aware of the cycle of toxo…glad all is well…

  6. jewelofmisanthropy said, on September 30, 2010 at 11:56 am

    Great post – informative and fascinating. I have long been interested in the “mind-control” potential of infectious diseases. I think that some of the scariest stuff I’ve seen was about this fungal infection called Cordyceps that afflicts mostly insects. It controls the creatures behavior, driving it upward to achieve optimal temperature and humidity for growth, and also to ensure that once the fungus has erupted out through the insect’s body and it’s spores burst forth that it has the maximum distribution range.
    you can watch a video about it here:

    anyway, as I said, great post, and congrats on testing negative. Good luck with your pregnancy!

  7. Anna and Her Biro said, on September 30, 2010 at 11:58 am

    Yay. So good to know you have the all clear. It’s funny how when we are super aware of something we are convinced we have it. I am training to be a psychotherapist and we are learning about all sorts of behavioural/mental (etc) disorders – and I have so far diagnosed myself with a handful. haha.

    Thanks for blogging and congrats on getting being Freshly pressed!

  8. Picscribe said, on September 30, 2010 at 1:34 pm

    Congrats on being freshly pressed. Good anecdotal reading, While there has been an evolutionary explanation for the way the toxo affects rats, the problem is that there has been no replication of results with an artifical inducement of similar cerebral neurohumoral milieu.

    And as for your pregnancy, I wish you the very best.

    And just a parting thought: the way your immune system deals with the child you are carrying, which is essentially a foreign protein assemblage, is also one of the more beautiful aspects of immunology!


  9. Key said, on September 30, 2010 at 2:04 pm

    It’s like a pet you don’t have to tend and can blame all your personality flaws on. Very handy..

  10. Apes T. Sistem said, on September 30, 2010 at 7:13 pm

    Wow… Although I have read every kind of weird health diseases due to my even weirder teacher of biology on Sencondary, I’ve found your post quite interesting; especially the mind control part since I’ve always though that such thing could be possible.

    Nice explanation with no lack of details and nicer to hear the results were OK.

  11. boho fangirl said, on September 30, 2010 at 10:49 pm

    Very informative post! Reading about new or weird diseases are sometimes scary but it is important that we educate ourselves with these kinds of things. Thanks for doing that! 🙂

    View my blog too! (latest post about JLO and Ryan Seacrest’s catfight)

  12. Tee said, on October 1, 2010 at 12:59 am

    Wow. I’ve never read anything like this–makes me want to get tested right now. I think I’ve got most of the symptoms. I’m intrigued. I’ll have to read more about this.

  13. zonmatron said, on October 1, 2010 at 5:38 am

    Found this post at random, and I take a passing interest in science (as a languages student, it’s not like I study it in detail) First time ive heard of something like this. Very interesting stuff! Distracted me from going and finding food.

    Cool! Now if I get prone to any particular personality trait I can blame it on a parasite.
    Glad to hear you and the more usual type of parasite are unharmed.

  14. Storm said, on October 1, 2010 at 6:31 am

    “women tend to be warmer-hearted, dutiful, moralistic, conforming, easy-going, persistent, and more outgoing and promiscuous.” AH! I’m all these things! I’ve been infected for years!!!!!!

    I like the fact you referred to your fetus as a parasite.

    Interesting article. I like!

  15. teapotchronicles said, on October 1, 2010 at 7:22 am

    Hmmmm… Glad I’m a dog person… 😉

  16. ConspiracyTheory said, on October 1, 2010 at 8:48 am

    This sounds like something out of a conspiracy thriller – like one of those Dan Brown books with Illuminati plots:
    Very interesting to know it could be real!

  17. Katie Taylor said, on October 1, 2010 at 10:30 am

    I’ve been curious about this for the last few years (after I first saw a news article about it on Yahoo…not the best source of information). Interestingly enough, your blog has the most information on it that I’ve ever seen. Maybe you just presented it in a better way than those doctors…they tend to make everything sound deadly.

    Congrats all around (on the negative test and the baby).

  18. michaela said, on October 1, 2010 at 12:40 pm

    Very interesting indeed.
    I know of parasites that cause their hosts (in this case: dogs) to lose all their fur, so they can more easily be bit by mosquitos. For some reason similar to the rat’s one. Keeping the circle going…
    Kind of scary, though, isn’t it?!

  19. youhaveunicorncancer said, on October 1, 2010 at 2:18 pm

    This was a joy to read about! I don’t have a kid but I am sooooo interested in hearing a person who knows how to describe something to me, and me understand it enough to be able to see a picture of it in my head. The thing you said at the end about the line between getting fuzzy, thats something I never thought of. I am not a female so I don’t think about that kidna stuff lol, but its awesome to hear, that the mother must feel forever attached to the child…like in a weird kinda creepy way….like no wonder the mom knows what your doing when she shouldn’t have a clue…I bet there is some psychicness happening.

  20. Dan Patrick said, on October 2, 2010 at 5:16 pm

    Infected men tend to be more jealous but slow-tempered? Women tend to be more moralistic but promiscuous, conforming but persistent?

    I don’t see how these characteristics could co-exist in the same person. Persistence and confirming seem somewhat opposite to me… same with morralistic & promiscuous, and especially slow-tempered & jealous?

  21. Dan Patrick said, on October 2, 2010 at 5:17 pm


    I’m on my laptop and gotten used to a bigger keyboard. 🙂

  22. ownedbyrats said, on October 3, 2010 at 12:16 pm

    A very interesting post – which I was attracted to because of the rat photo 😉

  23. kelemta said, on October 4, 2010 at 11:21 am

    What a fascinating post, I’ll definitely be researching this further! And after it all, a good ending too.

  24. Tim Shepard said, on October 5, 2010 at 3:41 am

    insightful thoughts. I never really considered the point of view from a mother before. I’ll be checking back and thanks!


  25. prematureejaculationcauses said, on October 11, 2010 at 3:48 pm

    very nice post its great site i have to say…
    very good pic dud…

  26. health,health,health said, on October 24, 2010 at 6:57 am

    Wow! Really terrible. I think this is very imagination of Toxoplasma gondii is felt afraid. Pregnant women are also likely to be leaving because of the invasion of the bacteria and their brain is not clear, as they are being used magic, controlled himself as

  27. samuel said, on December 27, 2010 at 2:43 pm

    he only parasite I really don’t mind carrying is the baby

  28. Amaobi said, on August 25, 2011 at 8:01 am

    Wao.. this is very educative!

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