The way the data was collected looks like junk in the first place:
> The subject also had to answer a question “Are you infected with Toxoplasma, the cat parasite that is dangerous especially to pregnant women?” by ticking one of the three suggested answers: “I do not know or am not sure, I was not laboratory tested,” “No (I was tested by a medical doctor and the blood test gave a negative result,” and “Yes (I was tested by a medical doctor and the blood test gave a positive result.” Implicitly, the first answer (“I do not know …”) was ticked.
Ideally you would medically test the patients and make sure they are unaware for what they are tested. Asking them to answer such a question is going to massively decrease whatever you can say about what's claimed.
Read further; the subjects of this study were also examined and had labs drawn which included a toxo test, and were issued unique codes which they provided with their study responses:
> At the end of the questionnaire, the participants could provide their unique “guinea pig code.” Because of the rather sensitive sex- and health-related contents of this questionnaire, it was “signed” only by 8% of the responders. However, other questionnaires distributed in this community were signed by most of responders (Flegr & Hodny, 2016). These results showed that most of participants who were aware of their toxoplasmosis status (and nearly all male responders) had been tested for toxoplasmosis in our lab.
Unless I'm badly misreading the paper, they were therefore able to correlate study responses with confirmed presence or absence of latent toxo, with a high degree of specificity. It's odd that they would also include a question on the same subject, and I'm not competent to evaluate their methods of statistical analysis, but even the attempt to correlate study responses with laboratory data puts them head and shoulders above pretty much anyone else I've seen publish on this topic.
> These results showed that most of participants who were aware of their toxoplasmosis status (and nearly all male responders) had been tested for toxoplasmosis in our lab.
So they only had a confirmation for the positive/negative cases, but they have no way to confirm that the ones who say "not sure" were accurately reporting their answers. That's a pretty big gap they use to draw conclusions.
I'm not sure you've correctly interpreted that quote.
most of participants who were aware [...]
had been tested [...] in our lab.
This does not preclude any blood draws, in which the subject is tested, but not informed of results and infection status.
They can test samples drawn expressly for the experiment, and not inform the individual, and then still use the lab-verified determination of infection status in the results. They can take blood, find out, and not tell the people if they are infected, even if they didn't know, and let them stay infected without knowing.
Fair. But also this, the first sentence of the "Limitations" section:
> The major limitation of the present study is that it is based on self-reported information on subjects’ sexual life and self-reported Toxoplasma infection status.
They go on to caution against overgeneralization based on these extremely specific and inherently uncertain results, which is entirely reasonable, but I think it's rather hasty to write off the study as "junk". At the very least, it's better and more careful science even despite its limitations than one ordinarily sees performed in this realm.
In addition, unclear as to how this is causative rather than correlative. Perhaps people who keep pets, or cats in particular, are more likely to have the described personality traits.
Quick PSA: The number one method of infection for toxoplasmosis is foodborne from undercooked meat (which is why France has a 90%+ infection rate). Most people focus on cats.
While cats are a vector, this really only applies to cats allowed outdoors. Indoor cats bear no risk of infection.
The infection rate among adults in France is 50%. It is impossible for the whole population to have a 90% infection rate then.
Western Europe, excluding the UK, has a mean infection rate of 70%. The climate seems to be important for the transmission, and not simply the food regimen.
"No risk" seems a bit strong here. (Or maybe I'm just paranoid. But I was definitely in charge of the litter box when my wife was pregnant).
Could an indoor cat who has at some point shared a litter box with an outdoor cat have picked up spores (in the same way that a human might), for instance? Or, my cats were rescued as young kittens after their (stray) mother died: were they in the wild long enough to be exposed? (And how many cats adopted in the US have similar histories that their owners might not even have heard about?)
Cats exposed to toxo have finished shedding it after two weeks. If your cat has not been exposed to the outdoors or an indoor/outdoor cat in over two weeks, they are pretty darn safe. Maybe give it a month or two if you want to be extra sure.
I would never want to risk it because I've seen the damage it can do. My family fosters kitten litters with a nearby animal shelter. It's normally fun and rewarding work, but we once lost an entire litter to toxoplasmosis. It;s generally harmless to people and cats, but in young kittens who don't have very strong immune systems it becomes a degenerative neurological disease. The vets initially thought it was rabies from the symptoms: lethargy progressing to a loss of motor control. We had to clean the room we kept them in with bleach, wash all the cushions and blankets thoroughly, throw out all the cat toys...
I don't know what Toxo does to fetuses and infants, but based on what it does to kittens I'm not keen on finding out.
That's interesting. I used to eat meat well done. But then learned that it unless it is rare or at least medium I doing things "wrong". And indeed it does taste better when it is not cooked all the way through. Now reading this makes me rethink it.
I'm glad this made the front page, but I'm not really sure how. I know why I voted for it; it's rare to see any research worth taking seriously that has to do with latent toxoplasmosis in humans. I'm curious why anyone else did.
I haven't voted, but I am rather fascinated by the idea that cat parasites might be influencing human behaviour. Unfortunately I'm not really scientifically literate enough to evaluate the reliability of this and other research into the topic, but I'd like to know more.
It is fascinating subject, because it is zoonosis the pathology of the human brain might not be the same as in other animals. I'm not so sure that this study was done properly.
I've owned cats for awhile, and the idea of a cat parasite controlling or influencing my behavior (and the behavior of others) is both fascinating and frightening.
Plus, parasites are generally a bad thing, and there is not enough awareness about Toxoplasmosis.
There's some evidence to suggest parasitic infection can prevent or reduce some diseases, such as asthma or Crohn's disease.
One study published in an ATS journal concluded: "Parasite infections do not in general protect against asthma, but infection with hookworm may reduce the risk of this disease" [1]
I mean great, but you still have hookworm. It may well be worthwhile to identify and isolate what about having hookworm might be preventative for asthma and develop it into a therapy, but that's not quite the same thing.
Well, one commonly accepted effect of toxoplasmosis is an increased fondness for cats, and it's not hard to construct an argument that, at least in relation to modern humans, most cats pretty much are parasites.
So maybe you want to think about getting serotyped, is what I'm saying here.
What's especially interesting is that the described behavior in infected mice sounds like a fetish humans have called vorarephilia, and after reading this paper I wonder if the folks with that sort of fantasy are infected with Toxoplasma?
"However, they expressed higher attraction to bondage, violence, zoophilia, fetishism, and, in men, also to masochism, and raping and being raped. Generally, infected subjects expressed higher attraction to nonconventional sexual practices, especially the BDSM-related practices, but they also reported to perform such activities less often than the Toxoplasma-free subjects."
So uh, no actual experiment here. Even with the methods they're using we're not really getting causality. Seems like they're just saying cat people (or raw meat eaters) are more into BDSM.
That's not exactly what the study is saying, which seems rather to be that it makes people more kinky, but less likely to try to seek out partners interested in the same things they are.
That, along with the fact that the authors don't merely infer or assume latent toxo in their subjects but have actually observed it, is one of the reasons I find this study interesting. That it should make people less likely to seek out outré sexual adventure seems strongly counter-intuitive in light of the increased risk-taking behavior generally supposed to correlate with the infection, and that is at the very least curious.
Yes! I was confused by this, too. Everything else I've read about toxoplasma has stated that in humans, it increases risky (or risky-feeling) behaviour like motorcycling or sky diving.
But an infection that makes people more sexually submissive - that reads like the plot of a really silly piece of sci-fi porn.
> In agreement with our a priori hypothesis, infected subjects are more often aroused by their own fear, danger, and sexual submission although they practice more conventional sexual activities than Toxoplasma-free subjects. We suggest that the later changes can be related to a decrease in the personality trait of novelty seeking in infected subjects, which is potentially a side effect of increased concentration of dopamine in their brain.
This seems to be saying that they're more conventional in what they actually get up to (which I'm interpreting as being less kinky), even though they're more turned on by being in a threatened/submissive position.
Maybe they do seek out sexual adventures but are just more vanilla when they get down to it?
I don't know; that sounds sort of like a distinction without a difference. If someone who fantasizes all over the place but has vanilla sex isn't kinky, what's someone who fantasizes about sleeping with guys but stays faithful to the woman he married? Is the thought of a unicorn a real thought?
>infected subjects are more often aroused by their own fear, danger, and sexual submission although they practice more conventional sexual activities than Toxoplasma-free subjects
It is not making people "kinky" or adventurous. It is making them more reserved than the non-infected. Maybe because sexual desire caused by a brain infection feels uncomfortable and troubling? We can only speculate.
Why wouldn't it? A shallow compulsion might be good enough for mice, but troubling for humans who are used to experiencing more depth. It could be something more like OCD. There are people with "homosexual OCD" who aren't gay but who are obsessed with and troubled by the idea that they might be:
I don't know if that's a concrete enough distinction. The experience of desire is a very abstract theory-theory concept. What they report is distress that they may be experiencing the desire in question, which they are usually observed not acting on, but express fear that they might.
It sounds like a pretty concrete distinction. It's made clear multiple times that these aren't guys who want to sleep with guys; they're just hung up on second-guessing whether or not they want to sleep with guys, even though they know they don't want to sleep with guys. Hence "obsession", likewise "compulsion".
Speaking as a guy who does sleep with guys, and who has had considerable familiarity with other guys who do sleep with guys, I'm really having a hard time seeing a meaningful commonality here in terms of desire. I can't speculate on the question of psychological theory, and I haven't had an opportunity to discuss the matter with someone who suffers the condition described in the article, but I do know a little bit about what it's like to be uncomfortable with wanting to sleep with guys, and what we're talking about here really doesn't sound like that at all.
> The subject also had to answer a question “Are you infected with Toxoplasma, the cat parasite that is dangerous especially to pregnant women?” by ticking one of the three suggested answers: “I do not know or am not sure, I was not laboratory tested,” “No (I was tested by a medical doctor and the blood test gave a negative result,” and “Yes (I was tested by a medical doctor and the blood test gave a positive result.” Implicitly, the first answer (“I do not know …”) was ticked.
Ideally you would medically test the patients and make sure they are unaware for what they are tested. Asking them to answer such a question is going to massively decrease whatever you can say about what's claimed.