Toxoplasmosis: Morbid attraction to leopards in parasitized chimpanzees
> Researchers have shown that chimpanzees infected with toxoplasmosis are attracted by the urine of their natural predators, leopards, but not by urine from other large felines. The study suggests that parasite manipulation by Toxoplasma gondii is specific to each host. It fuels an ongoing debate on the origin of behavioral modifications observed in humans infected with toxoplasmosis: they probably go back to a time when our ancestors were still preyed upon by large felines.
Why do they say it's "specific to each host" and not some ultra-simple algorithm like "flip the sign on $PREDATOR_FEAR_COEFFICIENT"? One might suppose that "fear of predators" is a highly conserved, re-used mechanism across a wide variety of organisms that specialize it to different predators as an "implementation detail", and toxoplasmosis attacks some feature common to everything rather than having a huge database of different creatures and their predators. Perhaps that is what they mean, but it's an odd way to put it.
> The primary mechanisms of T. gondii–induced behavioral changes in rodents occur through epigenetic remodeling in neurons that govern the relevant behaviors (e.g. hypomethylation of arginine vasopressin-related genes in the medial amygdala, which greatly decrease predator aversion).
It's got a whole list of different things that it does. Yes, some of that could be "epigenetic tweaking a gene that looks like this" would have different effects in different species (and even different genotypes - different effects for men and women). Changing the epigenetic of the regulatory genes can do different things in different species where the regulation genes have taken on different functions.
>> the men were more likely to disregard rules and were more expedient, suspicious, jealous, and dogmatic. The personality of infected women, by contrast, showed higher warmth and higher superego strength (factors A and G on Cattell's 16PF), suggesting that they were more warm hearted, outgoing, conscientious, persistent, and moralistic. Both men and women had significantly higher apprehension (factor O) compared with the uninfected controls.
It's weird that this infection makes one more risk-embracing and "likely to disregard rules," but the subjects score higher in the apprehension factor. Doesn't that mean they are somehow becoming adventurous worrywarts? (Or did I misunderstand something here).
My ex girlfriend's family used to have their cat litters right next to the kitchen table. Any bad behavior or decisions I've made since then I'm going to blame on her and my "taxoplasmosis".
I feel that naming one specific presentation of an infection for the pathogen isn’t so tenable now that we’ve realized there are multiple presentations.
There are antibody tests to show if you've ever had it, and approximately how intense/active the infection is. Mild latent and recent past infection is hard to distinguish apart from an antibody test alone. Decreasing antibody concentration over time = fighting it off successfully, or past infection fading away (probably). Antibody tests like that aren't terribly expensive. (Well under $100 here in Canada if uninsured.)
Direct testing for the parasite's DNA in the cerebral-spinal fluid (yeah, a spinal tap sorry) is sensitive, too. Attempting to detect it elsewhere (blood, etc.) works but isn't as reliable. This is more expensive but sometimes used when unsure. Otherwise, in combination with that, it's diagnosed symptomatically. It shows up on a brain scan if the lesions get big enough, not to be alarmist.
If it is not controlled by the immune system, it causes general neurological disorder, potentially severe (Parkinson-like, dementia, brain damage), and can start to invade other organs. This is uncommon except in people with serious immune dysfunction.
When an infection is latent, it's normally described as asymptomatic. But there is some reason to think, it might subtly affect humans neurologically in a similar way to how it seems to affect other mammals, like the wolves in this article. But this is controversial.
I’ve always found the term ‘immunocompromised’ to be somewhat vague.
I use immunosuppressive medication to manage a chronic condition, so I assume my immune function is worse than someone not using such, but better than e.g. someone undergoing chemotherapy.
Does this make me immunocompromised or not? Or, where does it place me on the scale? What precautions should I take?
The question is how your medication interacts with "somatic hypermutation" which enables your dendritic cells to launch the cascade via t-cells which triggers antibody production by your b-cells.
It would be useful to understand how your medication interacts with this process.
Somatic hypermutation has a small discussion in the Kerzegast book.
I understand that somatic hypermutation, by the removal of uracil, plays two roles, first in initial recognition of a pathogen, then second in tuning the response for variants.
As I understand it, this only happens in germinal centers, the lymph nodes.
You're also immunocompromised if you slept poorly or are dehydrated or malnourished (as many are, even if they don't know it). I agree that it's a poor blanket term.
No judgement here. If I was dating, that would be my dating pool...
In all seriousness, since this topic comes around every couple years, I've always wondered if we tested different populations of people based on career if we'd see some correlation. Cats are fairly ubiquitous across populations (but knowing if there's a higher prevalence in some would be important), so there's at least a chance for most people to be exposed I think.
1) Almost everyone who has it got it from eating undercooked meat, not from cats. France has the highest rate of toxoplasmosis in the world because of their propensity for rare meats: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312802/.
2) Unless your cat lived a long part of it's life as an outdoor cat, it is very unlikely to have the parasite (like any parasite).
I read your linked piece. It’s about pregnant women and toxoplasmosis and variations in treatments and outcomes in France and the US. I didn’t see anything about rare meats, and I only saw comparisons in infection rates among pregnant woman, women of child-bearing age, and infants in France vs US and a mention of South America when comparing type diversity. What am I missing?
Overall, eating raw or undercooked beef, lamb, or other meats; contact with soil; and travel outside the country were major sources of infection.
Contact with soil is from cats shedding oocysts, as covered earlier in the same extract, and while that doesn't necessitate owning a cat, I would classify it as exposure to cats (your neighbors outdoor cat shitting in your yard is still cat exposure to my sensibilities).
The association of cats and human toxoplasmosis is difficult to assess by epidemiological surveys because soil, not the cats, is the main culprit. Oocysts are not found on cat fur and are often buried in soil along with cat faeces. Therefore, direct contact with cats is irrelevant with respect to T gondii transmission, and soil contact is universal and difficult to avoid.
Which doesn't say cats don't matter, just that direct exposure doesn't matter. Soil exposure is exposure to cats through an intermediary, just not direct. It will still likely be affected by prevalence of cats in a population, even if not necessarily at a household level.
So, I think the article answers my original question to a degree, but I also think your claim that almost everyone that has it got it through eating meat with it in it is too strong given the sources you quoted (thanks a lot for posting them though, it's always nice to have data for a discussion!). If you think my reading of it is incorrect or I'm missing something, please let me know though.
Yes, that's more what I meant - there's almost no cases just from owning cats, it's from dealing with contaminated soil from stray cats. But the internet zeitgeist is "cat litter boxes give you toxo!" which is just not true the vast majority of the time.
> Could a brain parasite found in cats help soccer teams win at the World Cup?
> ...
> If we set aside the qualifying rounds (in which teams can play to a draw) and focus on matches with a clear winner, the results are very compelling. In the knockout round of this year’s tournament, eight out of eight winners so far have been the teams whose countries had higher rates of Toxo infection. If we go back to the 2006 World Cup, seven out of eight knockout-round winners could be predicted by higher Toxo rates. The one exception to the rule was Brazil’s defeat of Ghana, a match between two nations that each have very high rates. (Aside from having the winningest team in World Cup history, Brazil has quite a few cases of Toxo: Two out of three Brazilians are infected.)
> It gets better. Rank the top 25 FIFA team countries by Toxo rate and you get, in order from the top: Brazil (67 percent), Argentina (52 percent), France (45 percent), Spain (44 percent), and Germany (43 percent). Collectively, these are the teams responsible for eight of the last 10 World Cup overall winners. Spain, the only one of the group never to have won a cup, is no subpar outlier—the Spaniards have the most World Cup victories of any perpetual runner-up.
... and yes, that that's not a science paper. Slate is far from being a paper hosted at NIH. ... so...
> Potential linkage between Toxoplasma gondii infection and physical education scores of college students
> ...
> The overall seroprevalence of T. gondii was 11.5%. The main risk factors related to T. gondii infection in college students were cat in the household and gardening or agriculture activity. Furthermore, in the basketball group and the soccer group, scores of T. gondii seropositive students were significantly higher than those of seronegative students, while in other sports there was no difference between scores of T. gondii-infected students and T. gondii uninfected students.
Yes. I don't know exactly how cheap, but it's a big risk for pregnant women (not to have it, but to get infected while pregnant), so they have tests available, and it was affordable enough that my fiancee did it as part of her a prenatal screening.
Something like a third of the world population is estimated to be infected. More like 1 in 10 in the US.
Two questions, why do you care and what is anybody going to do about it? (The answer to the second question is “almost certainly nothing”)
There was a now discontinued (US) blood pressure medicine called guanabenz which studies were showing some effectiveness against the latent stage, but it’s no longer available.
Reading about the treatments, good luck getting ahold of the medicine required to maybe kill a latent infection unless you’ve got some serious risk factors (like AIDS). And I didn’t check but I wouldn’t be surprised if they’re the kind of thing you don’t want to take unless you have to.
This is legitimately super interesting, but I can't help imagining a wave of "alpha male bootcamps" where you pay thousands of dollars to handle cat feces for a weekend in the hopes of being infected.
You can sell supplements with “TP neuro extract”, with action identical to natural toxoplasmosis without infection. Avoids legal issues and makes them more alpha on a subscription basis.
Looks like enough people are coming sufficiently fresh to this topic to benefit:
Professor Robert Sapolsky at Stanford had Toxoplasma and it's manipulation behaviors as a research interest for a period.
He's a successful popular science writer and I think many people appreciate his informal lecture style as entertaining.
I don't remember which are the best presentations he's given on T. gondii but here's one that appears to be high-ranking on search at least
Was there not research in the past few years that took a look at motorcycle deaths and there was some correlation between the individuals that did not wear helmets and those that were also infected with toxoplasmosis?
I want to believe it because it makes a great science story and it makes good reading but who knows? This meta analysis only shows there is some correlation with behavior changes (only schizophrenia seems to consistently have some correlation) and discusses the difficulties in doing studies in pretty easy to understand way IMHO, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8548174/ The very high 30 percent infection rate among the world population is kind of like like herpes, which at first thought would seem to confound things, though at a glance at a few, the studies were careful to separate infected versus non-infected.
Hmm, it seems there are two different Toxoplasmosis/Accident narratives floating around out there: (1) That infection causes risky behavior and (2) that infection harms reaction-times so that accidents are more-likely or more-severe.
I suppose both could be true, but isolating the effect(s) means different kinds of studies.
I love stuff like this, but I can't help but wonder much of this is simply editorialization on top of natural selection.
Do infected wolves really take more risks? Or are we just connecting two dots with a thin bro science understanding of evolution? It seems impossible to know when you're looking for a broad narrative that fits how genes are spread
No doubt it could be over-interpreted, but seeing toxo correlate with risk-taking behavior in enough different species, does seem to increase the plausibility, otherwise we need special pleading that we have several different spurious correlations all pointing in the same direction.
However, and maybe this is what you're getting at, it could be that risk-taking individuals are more likely to get infected with toxo? Telling the difference between those two ideas would be harder, although in lab rat experiments you could control for it.
"This asymptomatic state of infection is referred to as a latent infection, and it has been associated with numerous subtle behavioral, psychiatric, and personality alterations in humans.
"Behavioral changes observed between infected and non-infected humans include a decreased aversion to cat urine (but with divergent trajectories by gender) and an increased risk of schizophrenia. Preliminary evidence has suggested that T. gondii infection may induce some of the same alterations in the human brain as those observed in rodents. Many of these associations have been strongly debated and newer studies have found them to be weak, concluding:
"On the whole, there was little evidence that T. gondii was related to increased risk of psychiatric disorder, poor impulse control, personality aberrations, or neurocognitive impairment."
There is a lot of evidence out there for diseases and specifically parasites modifying host behavior, toxo does indeed settle in the brain, and there is quite a lot of evidence for toxo specifically modifying behavior in different host species.
Doubt is always healthy but this one is not at all hard to believe.
You're far more likely to become infected with T.gondii from eating rare meat than you are from having a pet cat. Infection is more highly correlated with diet than cat ownership, with populations from countries which eat more rare meats having much higher rates.
I remember an article in the Economist between 2000-2010 claiming this was the cause of French drivers acting more reckless and aggressive in traffic compared to other countries. Not a subscriber anymore so sadly can't find the link in their archive.
Internet is full of cat pics. People love them. Now, in the world of cryptocurrencies, although meme coins started with dogs (doge), cat meme coins are now catching up to if not equal to dog meme coins in popularity and marketcap. Examples here: https://coinmarketcap.com/view/cat-themed/
.
Loud thought: Far fetched idea, but do you think there is a REMOTE possibility that Toxoplasma Gondii could be the cause of that? The cause of humans elevating imaginary cat tokens to god-like status by putting enormous amounts of money on them?
There's so much BS around toxoplasmosis online. Here's corrections for two common misconceptions:
1) Almost everyone who has it got it from eating undercooked meat, not from cats. France has the highest rate of toxoplasmosis in the world because of their propensity for rare meats: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312802/.
2) Unless your cat lived a significant part of it's life as an outdoor cat, it is very unlikely to have the parasite (like any parasite).
There were quite a few studies researching the effectiveness of a blood pressure medicine called guanabenz against the latent stage of toxo with a significant decrease in brain lesions. It was discontinued and no longer manufactured for sale in the US.
In contrast, foxes who are infected become 'dopey' and almost domesticated. Lack of fear, increased affection, and showing some signs of obliviousness like food left hanging out of their mouths. Also sadly some other effects like it being potentially lethal. Even treated foxes still show signs of frankly, brain damage and are considered unreleasable.
It is interesting that an animal close to cats (in strategy and prey), and their larger relatives are affected so differently.
Toxoplasmosis: Morbid attraction to leopards in parasitized chimpanzees
> Researchers have shown that chimpanzees infected with toxoplasmosis are attracted by the urine of their natural predators, leopards, but not by urine from other large felines. The study suggests that parasite manipulation by Toxoplasma gondii is specific to each host. It fuels an ongoing debate on the origin of behavioral modifications observed in humans infected with toxoplasmosis: they probably go back to a time when our ancestors were still preyed upon by large felines.