Cats: Toxoplasmosis And You!

Cats!  Does the internet talk about cats enough?  Are you sure? Were that a headline, Betteridge’s Law dictates that the answer to that question would be “no,” so I’m going to fix that deficit by discussing a certain cat issue with you here.  Pull up a chair, grab a cat and enjoy purr-rusing this whilst petting your four-footed furry friend!

Today’s Topic:  Toxoplasmosis And You!

Start talking about cats and some wag will simply have to jump into the conversation like a muddy dog to make a feline-disparaging joke about toxoplasmosis.  So hey, let me tell you about toxoplasmosis, which yes is a disease that cats and you can get, but that I bet you know little about beyond its infamous street reputation which you’ve no doubt picked up like an STD from news organizations that really should know better.1

So, what is it?

Toxoplasmosis is a disease caused by a wee single-celled parasite that lives out part of its life in cats.  Named Toxoplasma gondii (“T. gondii” if you’re nasty), this little bug’s definition of a good life goes something like this: a cat eats something already infected with T. gondii.  The little guys survive the trip through the stomach and sexually mature, then mate inside a cell in the cat’s small intestine,2 to create a confetti of millions of oocysts, which are sort of like tough-shelled T. gondii seed pods.  These oocysts then pass out of the cat via kitty poop and can hang around in soil and water for as long as a year, hoping to get accidentally eaten elsewhere by something a cat would eat, like a mouse or a rat, which then in turn gets eaten by a new cat, thus completing the great circle of poop life.

It’s a weird life, but I guess no more weird than viruses, which also break into and hijack a cell’s machinery to turn out an endless clone army whose swelling ranks ultimately make the cell pop like a water balloon full of baby spiders, and then each one of those baby-spider-clones go looking to do the same thing in another cell to infect.  OK, yeah, maybe that is pretty weird come to think of it.  But that could also be said of life itself.3

What’s even weirder though is how T. gondii has apparently evolved to game that circle of poop life by making some subtle changes in the non-cat host’s behavior in its favor.  Briefly and non technically, T. gondii manages this crafty subterfuge through “epigenetic remodeling,” meaning that it affects how small sections of the mouse or rat DNA are used in the rodental organism, mainly changing the way the creature reacts to fearful circumstances.  The way a rodent’s “fear” and its physiological effects are “expressed” (via release of adrenaline to trigger its flight or fight response) are encoded within its DNA, so if T. gondii suppresses that bit of DNA function in a rodent, it gets a rodents with less fear – or to be more precise, the cat gets a rodent with less fear.4  Which is what it seems that a rodent with toxoplasmosis is more prone to – infected rodents have been shown (more or less anyway; see below) to also have worse motor function, a sort of ADHD-like resistance to sitting still, a desire to explore, and to move around faster,5 all traits that lead to rodents that are less good at running away and more likely to get noticed and caught – meal time for Mittens, sexy times for T. gondii!

But what’s the scandal?

T. gondii oocysts can infect a number of creatures, anything warm-blooded will do, even birds.  Once inside these non-cat hosts (like a rodent), the oocysts crack open and release a bunch of little guys like they would inside a cat6 who manage to asexually reproduce in the intestines and spread throughout the body, and then hide from the native immune system in little cysts, mainly in the brain and muscle tissues.  And then the little T. gondii cysts hope for a cat to come along and eat this non-cat host, so that their cycle of kitty-intestine-centric sex life can continue.

Remember how I said anything warm-blooded could catch a T. gondii infection?  That includes the animals we eat, and, yes, us.  Worse yet, studies appear to show that T. gondii may be affecting our behavior like it does in rodents – not leading to us being eaten by cats, but still.  A T. gondii infection never goes away, you have it for life, there’s no cure.  It’s a pretty frightening idea in the abstract, especially if you’ve seen Upstream Color.  And hoo boy, here it comes.

Little wiggly microscopic bugs are living in people’s brains and changing their personalities, like Star Trek II!  People only like cats because of a freaking brain disease! GET RID OF YOUR CAAAAATS!

Goddamnit, stop overreacting, calm down.  You better now? OK, now lemme explain to you why that perception of toxoplasmosis is some bullshit.

  • Much of this fear mongering comes from appallingly rubbish science reporting in the mainstream press, something which may sadly be found as reliably as YouTube trolls.  Even otherwise realistic articles about toxoplasmosis get hobbled right out of the gate with clickbait alarmist headlines like “How Your Cat May Be Driving You Crazy.”  One less-realistic article I found literally opened with “A mind-controlling parasite…” and kept rolling along with all the scientific restraint of an anti-vaxxer Facebook post, while another described toxoplasmosis as “crazy cat lady syndrome,” which is even stupider because animal hoarding isn’t restricted to just cats and is a completely unrelated mental health problem, which still doesn’t mean you’re 1005 “crazy.”  JFC it’s irritating that that people get paid to write this stuff – like “Donald Trump is tweeting again” irritating. Don’t believe their lies.
  • This is not settled science.  Not a lot of studies have been done, those that have been done often suffer from small sampling sizes of people, and some findings contradict each other.  There’s also that whole annoying “correlation does not imply causation” thing to consider too.7  No one’s yet sussed out if perhaps a T. gondii infection actually or seriously affects people’s actions in some way or if they already had such traits and habits that might have lead to an infection, for example.
  • Having toxoplasmosis normally has zero noticeable effect on your daily life, unless you’re an unborn infant or have a weak immune system.  So you may already be a winner!
  • That “personality-changing” aspect, if it does exist, has been wildly exaggerated.  Most studies that do find some correlation only show about a “ten percent swing in variability” (even in rodents), meaning that if toxoplasmosis is, I dunno, making you8 not mind the scent of cat pee (something believed to happen in rats, more or less – again, “iffy”), then you’re only going to not-mind it about ten percent less.  This can still be cause for some concern though, as a ten percent drop in your reaction times may cause a road accident – or video game death goddamn it – and no one wants a higher chance to get schizophrenia.9  Toxoplasmosis is not that fungus that hijacks an ant and makes it climb a tree and then release spores out of its head, or demonic rock & roll hypnotizing you into killing your parents.
  • Your cat isn’t forever some filthy little Typhoid Kitty to be shunned.  Cats can only get infected with T. gondii once, usually when they’re just learning to hunt.  An infected cat sheds the oocysts for a couple or three weeks, and then their immune systems clear the bugs out completely, and, like any good immune system should do, remembers what that invader looked like so it can keep it out the next time it shows up.  Indoor cats obviously can’t get infected via the usual routes, and you should already be keeping your little hunting horror indoors anyways. Yes, cats are the ultimate source of these oocysts, but as scientists can’t even find a positive correlation between cat ownership and having toxoplasmosis,10
  • A large percentage of the human population already tests positive for T. gondii, so it’s already too late!  Toxoplasmosis is found all over the planet, and it’s been guesstimated that one third to one half of all humans have it, depending on where you live and your cultural habits and standard of living: up to 84% of the French are suspected to have it, maybe 90% of people in poor areas with bad water sanitation, but only about a quarter of Americans, for example.  Say what you will about the French, but I doubt 84% of them have been handling cat poop and obviously 90% of poor people aren’t crazy cat ladies.
  • So where are most people catching toxoplasmosis from if not their not-so-contagious kitties?  Undercooked food and contaminated water. Most farm-raised pigs have it (up to 92% of them), and sheep and goats are also commonly infected (about 78% and 53% in the US).11  Chickens are usually free of it though as they rarely get a chance to go outside; those that do may have an infection rate as high as one hundred percent. Cows too can get infected, but like cats, manage to rout T gondii for good, so the average cow is probably not too much of a risk.12  So yeah, you’re much more likely to catch it from eating poorly cooked meat, especially if your cultural traditions favor undercooked meat. But wait, we’re not done here. Have you ever been gardening or played in a sandbox but didn’t wash your hands later?13  Speaking of gardens, how much uncooked and perhaps improperly washed fruit or vegetables have you eaten in your life?14  After cutting up that meat and garden produce, did you thoroughly wash your cutting board and utensils?  Have you been foolish enough to drink unpasteurized milk? Maybe you haven’t always had clean water? The little T. gondii oocysts can end up in run-off thanks to cats and farming being everywhere, so have you had any raw seafood like sushi or oysters on the half shell?
  • Scientists covered by legitimate publishers/reporters that say they know themselves to be infected also say they aren’t worried about it.  If they’re not, why should you be?  Scientists are easily worth any three of you lot!
  • The average human being already has ten times as many unicellular bugs on and in them as they do human cells.  You’re not so much a discreet organism as you are a coral reef-like web of life.
  • Toxoplasmosis is nothing new for humanity.  I couldnt find any mention of how long people have been catching it, but it has been found in two thousand year-old mummies (makes sense, the Egyptians loved their cats).  With that in mind, my semi-educated guess would say it probably goes back before we even started commonly living around cats at the dawn of farming,15 because people were filthy animals before we invented soap in, when was that, like 1923?
  • And here’s a bit of good news: it’s been noted that T. gondii infection has been dropping in the US.  Hooray for soap and agricultural water runoff regulations!  (Wait, who’s in the White House right now?)

Feel better now, less tense and worried?  Good, so now I’m going to fan those flames by telling you about some of the effects that some scientists think toxoplasmosis may have on people.  These are just correlations,16, not solid evidence of our impending doom from the hypnotic eyes of our purring little hellbeast.  Remember, most people don’t have any symptoms or any severe ones at all, but those who do may show:

  • Slowed reactions times, which may be leading to
  • Higher rates of traffic accidents
  • Higher chances of being bipolar, schizophrenic (again, most people with schizophrenia do not test positive for toxoplasmosis), developing Parkinson’s disease, and Alzheimer’s disease.  So that’s not fun, but it’s also not a foregone conclusion, you can suffer any of those without T. gondii’s helping things along.  It’s also not the only infectious agent that’s been connected to such mental disorders.
  • Men who test positive for T. gondii may be a bit more devil-may-care about rules, be more OCD, suspicious, jealous, and dogmatic, while having a touch more fear (huh, that’s not like the rodents is it?)
  • Women may show more emotional warmth, be more outgoing, conscientious, persistent, and moralistic, and also be a bit more apprehensive like the men; they’re also more likely to give birth to a boy (72% compared to the usual 51% chance for a son17) and are a bit more prone to suicide if they’re over 60
  • People inadvertently hosting a T. gondii party have higher entrepreneurial activity and are more likely to declare pre-business as college major.  (Shudder) OK, maybe it is time we do something about this!

Oh god, toxoplasmosis is going to be the end of us!

Ha ha, got you all wound up again!  No it won’t be the end of times for us, but if you’re still all super fearful of toxoplasmosis, here’s some steps you can you can feverishly follow to keep this clawing nightmare at bay, as you can’t just rid the planet of cats themselves:

  • Properly prepare and cook your food.  Freezing it down to to 10.4°F/–12°C or cooking it up to an internal temperature of 152°F/67°C will kill any T. gondii cysts.  Scrub your veggies well and wash your utensils and cutting boards.18
  • Pregnant women shouldn’t clean cat litter boxes,19 not handle raw meat, drink raw milk (especially goat milk), eat raw or undercooked meat, or do gardening – at least wear gloves if you do garden.  And hey, you know what? Everybody should follow most of these guidelines anyways, although I suppose someone will have to do the cat box sooner or later.  Sigh, it’s going to be me again, isn’t it?
  • Remember that indoor cats are no threat (unless you try to rub their bellies too much).  You can help keep them T. gondii-free by feeding them dry, canned, or cooked food and by “discouraging their hunting and scavenging”, but good luck with that if they’re outside.
  • Keep litter boxes clean as the oocysts actually aren’t infectious until after they’ve been outside kitty for 24 hours.
  • It doesn’t apply to most of us in the first world (unless Trump’s EPA gets to work), but avoid drinking water that hasn’t been properly purified.
  • Doing some gardening or other outdoor activities that put you in contact with the soil?  Again, pregnant or not, wash your hands afterwards you filthy barbarian, or maybe wear gloves.  It’s not like this really needed being said right? This is why you wash up before dinner. Look, I’m not your mom here.

That’s exactly the sort of article I’d expect someone infected with toxoplasmosis to write.

I’ve not been tested, but… Iä! Iä!  The Black Cyst of the Woods with a Thousand Young!  One of us, one of us! Pet my kitty, one of us! Kibble kobble, one of us!  Faster, pussycat, infect! Infect!


Megara Justice Machine has repeatedly been accused of being a cat online and he would have gotten away with it too if it wasn’t for you meddling kids.  He irregularly contributes irregular articles about cats and science stuffs (including pumpkin spice!) to The Avocado, so you could do worse than to enter his name into the The Avocado search feature to find these curiosities.  Or, I dunno, read a book or watch a Werner Herzog film; maybe bake a cake. Anyways, cats!