Toxoplasmosis is an extremely interesting parasite. I wouldn't be surprised if it is recognized as an important public health issue in the coming decade.
Is has been linked to all sorts of disorders, including schizophrenia and bipolar disorder. Prof. Jaroslav Flegr contributed many important studies, especially in the early stages of toxoplasmosis research [1]. He was also featured by an Atlantic article, which was one of the first to bring public attention to the field of research [2].
One particularly interesting finding is how it interacts with the RH factor. It might explain the relative stability of the distribution of the two types in the population even though one of them should have a serious disadvantage (birth complications) [3].
The hard question is how to prevent it. Due to how many different infection vectors there are, the only sound pieces of advice are "eat your meat well done" and "avoid getting in contact with garden soil". Development of a vaccine for cats is a promising solution since the parasite can only be transmitted by cats.
After learning about the perverse incentives for publishing scientific papers, I find it extremely difficult to trust new research. Any tips for reversing this mindset? I know it's not too great to be feeling this way.
Scientists have immense incentives for publishing new results. As someone quipped, "there is no cost in getting something wrong; the cost is not being published."
Toxoplasmosis in particular seems intuitively like the perfect combination of new research plus massive prestige for whoever publishes papers on the topic. And we can't trust articles written on the topic either; they do little more than parrot whatever the scientists say, and don't really cast a critical eye on the methodology or findings.
Which makes sense. I mean, how could they? None of us are experts the way a scientist is an expert. But it used to be a hobby of mine to dig through research papers and find subtle inconsistencies. Take fatal familial insomnia, for example. It's not fatal due to the insomnia. That's a misnomer. But the fact that it wasn't related to the insomnia was buried on the 7th page of the report as basically a footnote.
I don't know. I just wish it were easier to take a lot of this at face value.
>Toxoplasmosis in particular seems intuitively like the perfect combination of new research plus massive prestige for whoever publishes papers on the topic
Eh, not really much prestige, but perhaps lots of press.
The big thing is to not take any single paper as "scientific truth" like what you read in a textbook. The scientific literature is not a textbook, it's the place where science's self-correction happens. Things in text books have been battle-tested, and widely accepted usually due to replication. And even then, textbooks have errors and perpetuate some falsehoods! Any individual scientific paper will not even likely be replicated, because it's working on something that did not turn out to be fundamental to the path of science.
Scientific papers in the literature are how scientists share their small steps while exploring the n-dimensional world. That n is very high, so there are lots of directions to explore, and most of them will not be that interesting. If it is, somebody else may decide to take a look too. If it's a hot-topic, then many many people will. Scientists have to operate in a world where they are exploring what is and is not true, and their relationship with uncertainty is strong; it's absolutely essential to embrace uncertainty.
The biggest thing is to distrust news reporting about science. It's correct about 1% of the time. The motivations of a reporter trying to somehow make an interesting article by deadline on a topic they don't understand are far more distorted than the scientists publishing a paper they expect 30-50 people to ever read. And that's if you actually get a real reporter to look at these things; most articles are just press releases that are cut and pasted from a university press lackey into the newspaper's publishing system. Those are usually even worse.
> And that's if you actually get a real reporter to look at these things; most articles are just press releases that are cut and pasted from a university press lackey into the newspaper's publishing system. Those are usually even worse.
Actually if the researchers expect the paper to be high impact they will often provide the press release to the University's press department themselves - these types of press releases are merely a layman directed abstract and tend to be reasonably OK.
This raises two interesting points.
1. Sometimes the lowest quality newspapers have the best quality article on a given publication.
2. Why aren't all research publications required to be accompanied by a second abstract written in plain low jargon language that can be understood at some level by someone with high school science?
I think maybe it depends a little bit on which university it is: perhaps a small university will not have enough money to hire a big dedicated PR office, so they will rely more on materials submitted directly by the scientist and stick closer to reality. But the PR offices of big universities (in particular MIT) put out pure hype which is very precariously connected to reality. A lot of work goes into these press releases (they will send someone from the PR office to interview the researcher and so on), but the work is not really aimed towards providing an accurate summary of the research...
To #2, because even putting aside how many scientists would have no interest in doing that, they would also be generally unqualified. Being a good researcher doesn’t make you a good teacher, and you need to be a very good teacher to turn your results into something a high school student could understand, and yet which still communicates your results accurately.
You're absolutely right here. Many journals do #2, and I generally find these to be worthless. For example, the Author Summaries on PLoS articles in a field that I'm not familiar with almost never help me. Often times when I read a paper in detail and journal club it with others, the conclusions that we derive from the data presented in figures has quite different emphasis than what is emphasized in the paper itself.
Sometimes with hindsight one can go back to a paper and say "this is important because of X" but it can be really hard to do that at the beginning, and often times the true value of the data may be different than the hypothesis under which the data was originally generated.
> 2. Why aren't all research publications required to be accompanied by a second abstract written in plain low jargon language that can be understood at some level by someone with high school science?
Because the target audience of research publications is other researchers in the same field; while outreach to nonscientists is fine, it's simply not the goal of a research paper.
Besides, for many papers this is impossible and/or pointless. My research results are incremental results in a specialized subfield of mathematics. I don't know how to explain them in anything but the vaguest terms to anyone without a reasonable background in that subfield, and I also don't know why such a person would care about them.
I can't quite agree, from my (albeit limited) observation, the copy-paste hype from press offices is almost always the source of ridiculous overstatements that make people distrust science. The press office's job is to make the university look as good as possible, and when they play the game of telephone with the researchers, they tend to overhype far more than a disinterested reporter would. MIT press office in particular is terrible at this, as are many lesser-known but aspiring schools.
> I find it extremely difficult to trust new research. Any tips for reversing this mindset? I know it's not too great to be feeling this way.
Why is it not great to feel this way? You give a bunch of good reasons why it is okay to feel as you do.
In general you should ignore any new research until it's had a large well run meta-analysis of it.
Until then, it's all "we think" and "maybe". And that's ok, unless you're forcing people to take a treatment or depriving them of their liberty based on the research.
I share your concerns, yet can't think of a solution. I think the only thing that can be done is to factor in a large amount of doubt, and amortize that doubt as more definitive studies come in over time.
>"After learning about the perverse incentives for publishing scientific papers ..."
Can you be more specific, what was the source or your learning? Was there a particular piece or pieces you read? If so would you be able to share them?
I'm a statistician and I read medical studies and experimental studies pretty much daily. My advice on a simple rule of thumb that is likely to separate out quality research: are the data and statistical code made available? Another, are if the study hypotheses and design are pre-registered. The Cox model is VERY popular, but you have to ask two things: is the hazard reasonably proportional? If you thought learning to code meant you had to be careful about mistakes and typos, statistics is another layer of a similar size.
> Toxoplasmosis in particular seems intuitively like the perfect combination of new research plus massive prestige for whoever publishes papers on the topic
While I absolutely agree with the general sentiment, some of the findings related to toxoplasmosis are well-replicated and supported by meta analysis, especially the link to schizophrenia and reaction time.
Flegr was mostly ignored for a decade and his findings are only now reaching mainstream recognition, after replication by independent teams.
Some of the recent "toxoplasmosis linked to X" papers are indeed of low-quality (low sample size and worse).
the biggest problem is the reliance on linear models and their interpretations.
its easy to have something statistically significant but yet produce a shitty prediction. they then take this horrible model and use its coefficients to make ridiculous claims, like doing X makes you Y times more likely to Z.
thats great for a business wanting to find ways to make money, but when this crap gets in the government level these crappy models are used to legislate us.
What would it mean to trust or believe in a theory? What finishing line in our minds does it cross beyond which we accept it as proven or regard it as confirmed?
I don't think there is one. We are fallible and even our best theories are tentative and provisional. When we do rely on ideas it only because we know no better alternatives.
Listen, the science presented is better than no science. I think you are conflating published peer reviewed articles with the incentives of Academic Institutions, Journals and publishing houses. In my view it's unfair to let the scientists be the antagonist in this debate.
Joe Rogan has talked about this at length on his show several times, and had Robert Sapolsky as a guest to talk about this.
They actually say the parasite causes rats to become sexually attracted to cats, causing them to pass on to the cat once it's inevitably killed. Life sure does find a way.
If you're starting a family, consider these words from Robert Sapolsky:
"The parasite my lab is beginning to focus on is one in the world of mammals, where parasites are changing mammalian behavior. It's got to do with this parasite, this protozoan called Toxoplasma. If you're ever pregnant, if you're ever around anyone who's pregnant, you know you immediately get skittish about cat feces, cat bedding, cat everything, because it could carry Toxo. And you do not want to get Toxoplasma into a fetal nervous system. It's a disaster."
"There's a long-standing literature that absolutely shows there's a statistical link between Toxo infection and schizophrenia. It's not a big link, but it's solidly there. Schizophrenics have higher than expected rates of having been infected with Toxo, and not particularly the case for other related parasites. Links between schizophrenia and mothers who had house cats during pregnancy."
And when you have that black hole very close (or over) that light part, it means that your toxo lesion is over the sport where all your eye nerves go, and then you become blind. Or almost, depending the exact position. Or you are "cured" but keep seeing eye floaters for the rest of your life.
This makes me wonder, if such a high percentage of people are already infected by this parasite why should mothers avoid handling cat litter boxes when pregnant? They're already infected, no?
Is the parasite dormant when it settles itself after infection? i.e. when you've been infected in the past, there is no risk to the baby, but if you're exposed to it again you can infect the baby?
Yes. After initial infection, which usually presents asymptomatically or with flu-style malaise, the parasites form cysts in the brain and stay there, where they aren't transmissible. The danger to the fetus comes with a new infection in the transmissible phase, which is likely to disrupt the fetal nervous system in lethal or severely damaging ways to which an adult brain isn't so susceptible.
(Source: I read a lot. Could be wrong! Don't think I am.)
This is why I am skeptical/cautious about the "let's just kill all the mosquitos" plans I see floated ...
Even if it's true that mosquitos can be removed from the foodchain with no negative effects ... are we so sure that wherever malaria goes (and I think it will go somewhere) won't be worse than mosquitos ?
If malaria had some other way to spread it wouldn't wait until mosquitos were wiped out to use it. It's not like the parasite is intelligent or anything.
I don't worry about malaria per se; as another poster noted, if it had a different vector, we'd see it already.
I do worry about removing critters from the food chain; we've seen plenty of second- and third-order surprises from that. What do the things that eat mosquitos find next-most-tasty, for starters?
The treatment for Toxo isn`t a easy one: when thing get serious you take massive doses of pyrimethamine and sulfadizine, for example, and have to take extra folinic acid (not folic, folinic).
And it won't kill all T. Gondii, it will remain latent inside your body.
There were some studied, few years ago, about combining pyrimethamine and aminoacids to kill the latent toxo, but I didn't find the results, if it even worked or not.
For almost everybody, infection will go away without signs. For few others, it will make you remember it for the rest of your life.
Thank you for this explanation! I listened to a long radio special about behavior assuring parasites a long time ago. Toxoplasma Gondii played a big role in the report and ever since I've been dumbfounded why we don't treat it. Even though it doesn't seem to have a negative immediate health benefit behavior alteration especially towards higher risk taking is terrifying to me. Thanks to your explanation of the cost of treatment this makes more sense.
They say about 20 percent of the US population has been infected and then we see this:
The research team found that 22 percent of the people with IED tested positive for toxoplasmosis exposure, compared with only 9 percent of the healthy control group. About 16 percent of the group with other psychiatric disorders tested positive for toxoplasmosis, too.
So the people with IED had about the same rate of infection as the general population. This looks to me like one of those "nothing to see here" situations based on the numbers.
Maybe not. That 9% number for the control group stands out. That number and the 20% number for the population as a whole seem to me to be incompatible - or, perhaps, measured in different ways.
If the 9% healthy and 22% with IED are both accurate (and the 20% number is the one that's off), then there may in fact be something to see here.
Perhaps healthy means younger than the general population and younger means less chance of having been infected yet. Those 20 percent of the population infected might be skewed towards old people.
Years ago I attended a lecture on Toxoplasmosis gondii. Intriguing (unattributed) points made by the scientist:
1) there's a higher prevalance of infection in car crash victims than control
2) by hijacking dendritic cells (blood immune cell), the parasite is able to bypass the blood brain barrier (highly protective filter of brain)
3) once in the brain, it may form cysts that may lay dormat
4) a significant portion of the world population is infected
5) if have cats weren't allowed as pets, there would hardly be any T. gondii infections
It is a difficult leap to go from saying "people with certain mental illnesses own cats, and thus are likely to have TP" to "TP causes mental illness".
If we are to believe cat owners are more likely to have mental illness, a correlation of mental illness and TP serum positivity follows naturally.
You could probably answer this question using this resource [1].
However, someone used it to show no associations between psychotic episodes (specifically) AFTER controlling for other factors (that are associated with cat ownership)[2].
Using the adjustments they made, I could wildly speculate that possibly dog owners will be less likely than cat owners to have mental illness, because dogs require a certain amount of wealth, living space, etc - and the lack of these things is associated both with cat ownership and mental illness, maybe, just not in rural areas...
Note that toxoplasmosis is extremely common and is sufficiently benign for most people that it does not really warrant worry or concern from the general populace. There are more important and actionable factors affecting most of us.
Yeah. I'm as fascinated by the theory as the next geek, but the evidence for a causal connection has remained pretty thin for awhile. The case for lithium in ground water reducing incidence of depression and suicide seems stronger. So if one is worried about toxoplasmosis then maybe they should also be buying pallets of Pellegrino, as it's the most widely available bottled water with the highest concentration[1] of lithium. It's part of how I justify the expense to my spouse :)
[1] It's still only a small amount. You can actually buy lithium water on Amazon with orders of magnitude more lithium, but that seems unwise....
It makes one wonder how healthy those home-grown salad vegetables might really be, given that a garden plot makes a convenient litter tray for roaming felines.
Some buddies work in a lab doing all kinds of product (mostly but not exclusively food) analysis for chemical and biological contamination, pesticide levels, etc; and they also do some research and run the same tests on all kinds of stuff they find personally interesting, including things they would personally consume.
Their experience is that the general commercial products are the safest to use - all the organic small scale farmed stuff sold to the general public is highly hit and miss, sometimes they're less contaminated but quite often it's literally off the charts e.g. hundredfold exceeding the limits allowed for commercial products, or have all kinds of dangerous bacteria (indicating e.g. fecal contamination) that they've never seen in samples of the mass produced food. Also, things their relatives have grown not for sale but for themselves with the purest intent have sometimes been contaminated - e.g. some parasites in their pork.
TL;DR - home-grown stuff can be expected to be less healthy and more dangerous than the industrial farming processes in well regulated first world countries. Often more tasty, though.
I must admit I didn't know about the feral cats wandering around farms. But I do imagine that farmers wash their produce more consistently than home growers do, and that feline density is higher in the suburbs.
This very much depends on where you grow up. Plenty of countries in the world where you can live a comfortable middle class life and still be around a lot of stray cats.
So I had a thing with this as a young kid. It caused burn-like scars on my retina. No symptoms after that or vision changes. Did it alter my brain? I don't think so. I will rage in my car when someone is in the left lane driving slow.
There is so much visual processing machinery in the retina that some neuroscientists describe it as an outpost of the visual cortex. In that sense, scarring your retina might indeed have altered your brain. But not in a way that's related to emotional control.
Honorable Members of the Jury, you can clearly see that my client couldn't possibly be responsible for his actions, as he just ingested a Twinkie with a Soft Nougatie Cat Feces Filling!
Is has been linked to all sorts of disorders, including schizophrenia and bipolar disorder. Prof. Jaroslav Flegr contributed many important studies, especially in the early stages of toxoplasmosis research [1]. He was also featured by an Atlantic article, which was one of the first to bring public attention to the field of research [2].
One particularly interesting finding is how it interacts with the RH factor. It might explain the relative stability of the distribution of the two types in the population even though one of them should have a serious disadvantage (birth complications) [3].
The hard question is how to prevent it. Due to how many different infection vectors there are, the only sound pieces of advice are "eat your meat well done" and "avoid getting in contact with garden soil". Development of a vaccine for cats is a promising solution since the parasite can only be transmitted by cats.
[1]: https://web.natur.cuni.cz/flegr/publ.php
[2]: https://www.theatlantic.com/magazine/archive/2012/03/how-you...
[3]: https://web.natur.cuni.cz/flegr/pdf/rhWho.pdf