The CATalyst: Getting Facts Straight About Toxoplasmosis; Your Cat Won't Make You Crazy

Steve Dale, CAT FANCY writer and syndicated newspaper pet columnist, provides a weekly cat news roundup.

By Steve Dale, CABC | Posted: March 15, 2012, 3 p.m. EDT

Steve Dale
Author Steve Dale

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Maybe your cat won't make you crazy, but stories like the one appearing in The Atlantic from March 2012 called “How Your Cat Is Making You Crazy” is more than a bit annoying. In places, this piece is anti-cat and anti-fact.

“The parasite, which is excreted by cats in their feces, is called Toxoplasma gondii (T. gondii or Toxo for short) and is the microbe that causes toxoplasmosis — the reason pregnant women are told to avoid cats' litterboxes. Since the 1920s, doctors have recognized that a woman who becomes infected during pregnancy can transmit the disease to the fetus, in some cases resulting in severe brain damage or death. T. gondii is also a major threat to people with weakened immunity”

I don't know why I need to repeat the facts about toxoplasmosis – yet again – but here I go.

Toxoplasmosis Defined
The Toxoplasma parasite is out there, occurring commonly in the environment. Infected prey or undercooked meat, both of which cats could eat, cause an intra-intestinal infection cycle unique to cats. Some cats with toxoplasmosis become ill, but most don't. This keeps owners in the dark about infected cats.

The organism multiplies inside the cat and is expelled in its feces. Cats are the only animal to pass T. gondii in its infectious stage via the stool.

Toxoplasmosis can indeed cause severe birth defects or even death in newborn human babies; however, a series of unlikely events must occur simultaneously for a person to get toxoplasmosis from a cat.
  • The cat, obviously, has to be infected. Most cats (especially indoor cats) are not infected, so they never have it to pass on.
  • Infected cats only eliminate the parasite the first seven to 10 days after initial infection. Even then, the parasite must be in the environment for at least 24 hours to become infectious. By scooping the litterbox once a day, that can't happen.

  • Keep in mind: The pregnant woman need not scoop the cat's litterbox. Family or friends can help out in this situation. If she does scoop, she can wear gloves and wash her hands to prevent infection.
  • The infection period must coincide with the first trimester of pregnancy for it to endanger the unborn child.
Aside from all of the above, women already exposed toxo have protective antibodies and are no longer at risk. Many, many women have those antibodies, according to the CDC, and most likely from uncooked meats or even gardening (where stray cats may have left their mark).  

Do Pregnant Women Need to Take Precautions?
Now, you tell me if pregnant women need to give up their cat(s). No relevant organization I know – the American Veterinary Medical Association, American Medical Association or Centers for Disease Control and Prevention — endorses the notion that pregnant women should even consider giving up their cat.

Many people with toxo only have mild symptoms or no symptoms – so they never know they have it. One exception are people with suppressed immune systems. Most doctors, though, agree cats provide far more benefits compared to any risks. Besides, toxo (as mentioned) is far more likely to come from other sources than from household cats.

Does Everybody Need to Take Precautions?
The primary assertion in the article is that the tiny toxoplasma organisms carried by cats may creep into our brains, causing everything from car wrecks to schizophrenia. What? Indeed, this is what Czech evolutionary biologist Jaroslav Flegr believes.

“The ‘latent' parasite may be quietly tweaking the connections between our neurons, changing our response to frightening situations, our trust in others, how outgoing we are, and even our preference for certain scents. And that's not all. He also believes that the organism contributes to car crashes, suicides and mental disorders such as schizophrenia. When you add up all the different ways it can harm us, says Flegr, “Toxoplasma might even kill as many people as malaria, or at least a million people a year.”

Kill more people than malaria? He's not kidding. But also he has no data.

The article does offer examples in nature of a parasite infecting and affecting the brains of various species. While they are all based on fact, there is no proof of a relationship in people infected by toxo, though several scientists have attempted to confirm Flegr's work.

True, some people infected with toxoplasmosis (you can tell because they carry the antibodies) have struggled with schizophrenia and other mental disorders. Some people with toxoplasmosis infections have ultimately committed suicide, scientists are unsure, however, what this proves – even if there is a general association (which remains unclear).  

According to the story, “[Flegr learned] the parasite is typically picked up from the soil by scavenging or grazing animals — notably rodents, pigs and cattle — all of which then harbor it in their brain and other body tissues."

I suppose science will ultimately prove Flegr right or wrong. We do know we've lived side by side with cats for a very long time, and so far, we're still here.    
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The CATalyst: Getting Facts Straight About Toxoplasmosis; Your Cat Won't Make You Crazy

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Reader Comments

CatChannelEditor    Irvine, CA

7/9/2012 8:07:23 AM

Thank you for your comment, Michael. Our author has researched this topic for several years, and confers with vets, the CATalyst council and many other cat health groups. The CDC website confirms his points on toxoplasmosis: LINK

Michael    Minneapolis, MN

7/6/2012 2:10:40 PM

I see a lot of information, but no sources. I would prefer that information is backed up with citations before using them for judgement on safety.

misty    amelia, VA

4/10/2012 9:03:03 PM

i dont even have a cat n 4 some reason have been sick 4 3 mths. drs thought i had lymphoma did a biopsy of my neck lymphnodes n it turns out to be toxoplasmosis! go figure! n no im not pregnant nor have i messed with cat feces. cant figure out how ive gotten it. its nothn to joke about n has been spreadn thru my body quicky. and can be very deadly soits nothing to play with! take a special antibioitic n a series of them 2 get rid of it. n the healn process takes a long time dependn on how long you have had it. toxoplasimosis is no joke and serious! i have never heard of it till now!

CatChannelEditor    Irvine, CA

3/30/2012 7:15:32 AM

Thank you for your comment. We refer to Toxo as a parasite throughout the article and included the phrase you mention in error. We have corrected it.

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