hckrnws
Parasites are everywhere. Why do so few researchers study them?
by sohkamyung
The book Parasite Rex (2001) by Carl Zimmer is fantastic, and it inspired quite a few researchers to go into the study of parasites: https://www.amazon.com/Parasite-Rex-Bizarre-Dangerous-Creatu...
The book manages to be gross and fascinating and occasionally beautiful.
Given the age, I'm sure some of the science is outdated, perhaps even by people who grew up reading the book. But it remains one of my favorites, and it's an accessible read. If not always a comfortable one!
> it inspired quite a few researchers to go into the study of parasites
That was me!
First I read Peeps by Scott Westerfeld when I was ~13, where ever odd numbered chapter is the story, and every even numbered chapter describes a different parasite.
At the end of the book was a blurb that said "if you enjoyed the parasite chapters, go read Parasite Rex, which I did. I loved it.
That book inspired me to take AP Bio, then get degrees in molecular biology and bioinformatics. In college I did research on a few different species of parasitic wasp for a couple years. I've written the wikipedia page for two different parasitic wasps and given numerous presentations on my favorite wasps.
The wasps are more of a spare time passion these days, though. It's much easier to make a living with bioinformatics and robotics.
I still keep my (well-worn) copy of Parasite Rex on the nightstand.
I remember listening to the radio (I believe on cbc canada), and one issue of studying any living thing is, whether your animal/creature of choice is in vogue currently or not. People below have mentioned funding which ties into that, but, if you're studying birds it's a lot easier to publish, there's more of an ecosystem and conferences, etc... than if you were to study some insect that nobody has heard of. Even within existing conferences you might not get "top-billing", even if you're presenting.
Pity as the things nobody has ever heard of are probably the most interesting.
I wish I remembered more details so could link something.
It's a pretty widely known thing that studying charismatic megafauna gets you lots of money. However, they're also generally WAY more of a pain to study. Fewer individuals, larger home ranges, expensive permits, etc. A good friend studies basking sharks and the shark research world is insanely competitive, full of crazy type A folks. Compared to the insect ecology world (where I come from), which is full of pretty chill stoners and weirdos.
I wonder if the group studying an animal slowly evolves to resemble this animal
That's interesting. I first read your comment, and I thought you were referring to the personalities of those studying an animal gradually changing as they unconsciously model their own behavior after that animal. This seems highly plausible to me.
But then I re-read it, and the second time it seemed to mean that the members of a group studying a certain animal would self select to favour those who are fascinated by and admire that animal. This also seems highly plausible to me.
Either way, it seems fitting that the world of shark study is full of "apex predator" researchers.
I think some of it is self-selection, but I also think some of it is a filtering effect based on the much more competitive and stressful atmosphere. Getting funding and permits and equipment to study sharks is a way more stressful process than walking around in a field collecting bugs. Not that collecting bugs is always easy, but the barrier to entry is way lower.
Good insight. I have thougbt the same or similar.
>I wonder if the group studying an animal slowly evolves to resemble this animal
IOW:
I wonder if the group studying an animal slowly evolves to look like this animal
likely
They smell like the animal much quicker. Presumably this results in some correlation in their gut flora
> They smell like the animal. Presumably this results in some correlation in their gut flora
Frankly, this claims are starting to be a little offensive.
Biologists take baths also when needed. Exactly the same as any other people. This would be not different than claiming that people that breed pigs, ends looking and smelling like pigs. Is not a productive way to drive this kind of conversations.
I started watching harp videos and they're all so calm and composed, like harp music lol. I really wonder if they're attracted to the harp because they're harp-like or if they became harp-like because of playing the harp.
The idea that you can change your personality just by choosing a field of study is for some reason very appealing to me.
> studying charismatic megafauna gets you lots of money
May I ask how so? Is it from producing popular documentaries or something? Or is there the research grant money from conservationist institutions or societies? (I can see how that wouldn't be there for parasites).
Donors. They want something that makes them feel good. Something to talk about at a cocktail party. LCM: large charismatic mammal; I'm saving pandas is better than the parasitic anderson wasp* that lives out its lifecycle in some gross fungus thing
*imaginary bug
Your point is well taken that pandas are probably a quick pitch for the right crowd, but “lots of money” seems optimistic for wildlife/conservation biology funding. That said, raising money for diseases of __human__ inhabitants of the developing world is typically quite a challenge. Counter to the focus of this thread, obesity is where it’s at right now for abundant funding.
It comes down to a lot of factors, but a big one is the diversity of funding sources. If you study a species that doesn't have broad appeal, you're probably looking at NSF funding, maybe USDA. If you study a game animal you can tap into all sorts of funding sources, like Ducks Unlimited, etc. You might be able to get state or federal wildlife agency funding. You might get a weird, wealthy donor who like sharks.
NSF grants are still the most important and impressive for most subfields within ecology, but the competition is fierce.
My takeaway is that to be an ecological researcher one must be crazy, weird, or stoned :)
Plenty of variability within that subset though! Lots of stereotypes based on your study system lol
thy username suiteth thy comment
"Or"? ;)
3 bi-di logical implications (between those 3 adjectives) is the right thing here ;)
Logical or is the default or, which allows for either one, either other, or one _and_ other
My takeaway is that to be an ecological researcher one must be intelligent, curious, capable and have the desire to help people to live better.
cliches are stupid.
This is an excellent book for anyone that finds this subject interesting: https://en.wikipedia.org/wiki/Parasite_Rex
Second this recommendation! Great book, lots to learn in it.
Well, researchers mostly use the subjects which are available which tends to be broke college students, studying corporate executives is more difficult.
> Parasitism is far from easy living; hundreds of millions of years of evolution have prodded parasites to find and manipulate other animals, just as those animals have evolved their own unique methods of survival.
Parasites manipulating their hosts is something that really fascinates me from an evolutionary point of view. An example given in the article is T. gondii [0]:
> [...] a parasitic protozoan that boasts “Mind Control,” because it attracts its rodent host to the smell of cat urine, where the rat spreads the parasite to felines.
Infected mice also have a reduced fear from predators, likely for the same reason.
I did my PhD studying manipulative parasites and in general, impacts of parasites/parasitoids on host behavior.
This is my absolute favorite example: https://journals.plos.org/plosone/article?id=10.1371/journal...
A parasitoid lays multiple eggs in a caterpillar host. The larvae eventually hatch out of the host's body, but do NOT kill it. They then need to pupate outside the host, which leaves them vulnerable to predation. Their former host, the caterpillar whose body they just violently erupted from, will then act as a BODYGUARD. It will body slam any insects that approach, knocking them away from the pupae. Truly the stuff of science fiction.
Another one of my favorite papers of all time: https://www.jstor.org/stable/29779588
There's a nematomorph parasite that infects crickets, and part of its life cycle is aquatic. It will induce crickets to jump into water and drown themselves (there are some crazy videos of this on YouTube). This study found that the allochthonous input (land to water) coming from the crickets jumping into a Japenese stream was a large part of an endangered trout species' diet. In short, his trout was kept alive because of a parasite driving crickets to drown themselves.
> This study found that the allochthonous input (land to water) coming from the crickets jumping into a Japenese stream was a large part of an endangered trout species' diet. In short, his trout was kept alive because of a parasite driving crickets to drown themselves.
The summary doesn't seem to follow from the finding. The fact that you mostly just eat crickets that walk up and ask to be eaten doesn't immediately imply that, if the crickets stopped doing that, you'd starve to death. It should be easy to understand the choice to go with a low-effort option even if there's also a higher-effort option available.
There's an inherent cost to foraging, so a high-quality food item that requires little effort is a much greater net energy benefit. When we're talking about an endangered species whose margins are quite slim to begin with, this can be a big difference maker. A couple dead trout reduces the population size, increases inbreeding depression, things aren't looking so good. I certainly oversimplified the mechanisms here, but a change in 60% of an organism's diet is not easily dismissed.
Ok one more, I can't help myself.
This one isn't really a manipulative parasite, but there is an isopod that will eat a fish's tongue: https://oceanconservancy.org/blog/2022/04/28/tongue-eating-l...
What's weird is that it then... basically acts like a tongue? It doesn't seem to be massively detrimental to its host, but it's absolutely insane to see a fish's mouth open and then there's just like, a little guy hanging out in there.
Comment was deleted :(
Jesus fuck. I knew about these guys but did not know they perform this by hanging out in fish gills until they get a breeding pair, them one crawls from the gills to the tongue to clamp on and replace the damned thing, and later they reproduce and spread young from the gills!
crazy, and terrible!!!
I'm loving your contributions to these comments.
Tangentially: assuming I had the drive + health to make the change, do you feel it would be a particularly challenging move for a software engineer to abandon their career to go back to school and study insects or other arthropods? I'm not a competitive person at all, and I saw your other comment above about the field, but I still imagine the money available for studying bugs is a tiny fraction of that for writing them.
That's an interesting question- I think it would be challenging in some respects, which would likely differ during and after school.
During a PhD program, you're not gonna make much money, but you will probably enjoy the classes and research, particularly if you have some money saved up from your current career to help smooth the bumps of living TA paycheck to TA paycheck. I really loved my PhD program, but was also in my early 20s and living like a poor grad student wasn't as big a deal.
As far as long-term career prospects go, I think things are a bit more challenging. There are opportunities to work for state or federal agencies, particularly if you focus on agricultural insect pests. Otherwise it's pretty much academia, and the job prospects there are pretty slim. Unlike other domains where there lots of non-professor jobs, for entomology and related fields, there are far fewer. Labs tend to be fairly small, so the total # of jobs nationally is also pretty small.
My advisor always used to say that he never knew anyone who didn't make it into a tenure-track position, if they were willing to hang on long enough. He also acknowledged that hanging on for a long time can suck! I wanted to start a family and live in a place where I had a community, so I left academia and work as a data scientist for a public transit agency near lots of friends and family.
What I'd say is that if you have a sense of the long-term career you want (agency scientist, ag researcher, tenure-track prof) and can go into grad school with a solid plan, you can make it happen. Entomology isn't a terribly expensive field, so you can do a lot without much funding, and that freedom can be really wonderful! But it's not going to be a particularly lucrative career, and competition for stable tenure track jobs is high, requiring a lot of geographic flexibility.
As you can see, I've got a lot of thoughts on this! If it's something you're seriously considering and want to talk more, let me know and I'd be happy to chat sometime.
Don't you think you're underplaying your hand here a little? The mechanism of this behavioral modification is in itself both beautiful and extremely spooky: https://en.m.wikipedia.org/wiki/Bracovirus
> Infected mice also have a reduced fear from predators, likely for the same reason.
In primates, there's some non-fear of cats too. For humans and domestic felines, this isn't much of an issue. For chimpanzees who share territory with leopards, this is more of an issue. https://www.nytimes.com/2016/02/16/science/a-parasite-leopar... (and the paper - Morbid attraction to leopard urine in Toxoplasma-infected chimpanzees https://www.sciencedirect.com/science/article/pii/S096098221... )
Ancestral humans shared territory with leopards, and children were vulnerable (1). Big cats are still dangerous.
Having a leopard stare at you, even through a fence, does raise the heart rate. But I don't know why we regard big cats so relatively favourably, when an evolved innate repulsion, such as to spiders or snakes, would make as much sense.
1) https://en.wikipedia.org/wiki/Leopard_attack#Leopard_predati...
The crazy jumping around people do when they are unexpectedly exposed to a proximate spider or snake might not be so adaptive for escaping large cats.
> Ancestral humans shared territory with leopards, and children were vulnerable
For a long time I've been interested in the fact that children are afraid that, if they are left alone, they will be eaten by monsters.
In the ancestral environment, this is absolutely true. But the belief is obviously innate and not learned. What's interesting is that the innate belief is correct in the details, as opposed to being something that is not necessarily true but nevertheless produces the correct behavior.
Cats are just aesthetically well put together animals. We probably also like the smaller ones due to 5000 years of them predating upon vermin that like to hang around our encampments.
> Cats are just aesthetically well put together animals
"They have a mat of messy protein extrusions in place of an exoskeleton, their eyes have no facets, and their thorax is completely indistinct from their abdomen!"
- Insect Aesthetician
"And a ghastly shortage of legs!"
While I subjectively agree about cats, "aesthetically well put together" is downstream of the "evolved innate" factors.
Faceted eyes wear your brain out faster from all the input. Maybe a bug would think they're a feature.
I don't agree with that kind of aesthetic relativism. It undermines both the nature of the mind as something that can objectively know reality (which undermines the relativistic claim at the same time), and the richness of reality itself. Materialism is bunk, and something that corrupts and replaced reality with some crude reductive imaginary thing.
Beauty is objective. Taste is subjective. Hence why we can say that someone has poor taste, i.e., the subjective fails to align with the objective.
I can admire the beauty of an insect as an insect without me being an insect. Similarly, if an insect were intelligent, possessed with an intellect, it could judge the feline as a beautiful creature as a feline.
"As X" is important, because it is a matter of how well the specimen realizes the telos of its species. Hence, why defect is ugly. You wouldn't say pi is an ugly integer. You wouldn't say a hammer is a crappy saw. You wouldn't say a fish is a bad mountain hiker, except as a shorthand for "fish do not mountain hike, are not anatomically + physiologically ordered toward hiking".
And of course there degrees of good, and therefore, beauty, based on how much more you resemble the Highest Good and therefore the Most Beautiful, Goodness and Beauty as such.
Cats have large, forward-facing eyes, and a relatively short snout and jaws (especially smaller cats like the domestic cats, caracals, etc). This makes them look less like a typical predator (long jaws, like wolf's) and less like a typical grazing animal (side-looking eyes, long jaws, like a horse or camel). They look close enough to humans to look cute, possibly triggering some if the low-level reactions which human babies trigger.
Arthropods and even snakes are morphologically too distant for that. Nevertheless, people usually find large-eyed geckos more cute than armor-eyed chameleons or tiny-eyed crocodiles.
5000 years isn't that long in evolutionary biology timescales. But culturally we do kinda like the usefulness of the smaller cats.
I would say that the cute cats are domesticated species, like many animals. So they wouldn't exist without humans, and it's in their benefit to behave to survive.
Interestingly enough, the genomes of wild forest cats and domestic cats have diverged FAR less than other domesticated animals such as dogs/sheep/etc. We domesticated other animals, but up until the 18th century or so I'd say it's more accurate to describe what we've done with cats as "co-evolution"
Cats are more "companion" rather than "domesticated" and (until recently) cats weren't bred for specific traits (and those now tend to be aesthetic choices rather than "practical" choices).
Compare this with dogs that are more of a "working animal." We've bread dogs to fill specific roles because they were larger to work with. If humanity had tried to find companionship in the mountain lion instead of Felis lybica (the wild cat).
Also for the how almost-domestic the African wild cats are: https://youtu.be/ZRqlSr1Yp1M
The other part of it (as I understand it) is that cats body form is not as easily selected for when compared to animals that humans have domesticated.
Dogs have a number of body sizes that can be "easily" selected for - https://embarkvet.com/products/dog-traits/traits-list/#body-... and https://embarkvet.com/products/dog-traits/traits-list/#other... (there's even a mutation of https://en.wikipedia.org/wiki/EPAS1 in wolves that was selectively bred into dogs https://academic.oup.com/mbe/article/34/3/734/2843179 )
I suspect part of the lack of range comes also from that the cats of size that don't eat us are not ones that can be crossbred with cats in the wild to introduce new useful genes. Trying to cross a domestic cat a wild cat doesn't produce a new cat that is useful in a new role ( https://en.wikipedia.org/wiki/Felid_hybrids#Confirmed_domest... ). Compare this with domestic dogs and the various wild dog species.
Dogs have twice as many chromosomes as cats. This makes it easier to selectively breed them for desired characteristics.
Dogs also have some features of their DNA that makes it more mutable than some other species.
MinuteEarth - Dogs vs Cats: The Diversity Paradox https://youtu.be/g1gj5yn5IyU
The 14 genes mentioned that control dog size: https://research.nhgri.nih.gov/dog_genome/study_descriptions...
The concept behind this is https://en.wikipedia.org/wiki/Phenotypic_plasticity
And linking to a reddit post about this from a while back - https://www.reddit.com/r/askscience/comments/1hhzcn/why_do_w...
Elevated basal slippage mutation rates among the Canidae - https://pubmed.ncbi.nlm.nih.gov/17437958/
> The remarkable responsiveness of dog morphology to selection is a testament to the mutability of mammals. The genetic sources of this morphological variation are largely unknown, but some portion is due to tandem repeat length variation in genes involved in development. Previous analysis of tandem repeats in coding regions of developmental genes revealed fewer interruptions in repeat sequences in dogs than in the orthologous repeats in humans, as well as higher levels of polymorphism, but the fragmentary nature of the available dog genome sequence thwarted attempts to distinguish between locus-specific and genome-wide origins of this disparity. Using whole-genome analyses of the human and recently completed dog genomes, we show that dogs possess a genome-wide increase in the basal germ-line slippage mutation rate. Building on the approach that gave rise to the initial observation in dogs, we sequenced 55 coding repeat regions in 42 species representing 10 major carnivore clades and found that a genome-wide elevated slippage mutation rate is a derived character shared by diverse wild canids, distinguishing them from other Carnivora. A similarly heightened slippage profile was also detected in rodents, another taxon exhibiting high diversity and rapid evolvability. The correlation of enhanced slippage rates with major evolutionary radiations suggests that the possession of a "slippery" genome may bestow on some taxa greater potential for rapid evolutionary change.
(and if you're interested in genetic diversity and fossil records, https://en.wikipedia.org/wiki/Cat_gap )
House cats are nearly genetically identical to wildcats. Which is to say, the species has always and still does exist without humans.
I've read, and like, a theory that their unpredictable movement is a big driver in the fear of spiders and snakes. I just found this with a quick search, for some evidence (it's not what I read originally, years ago): https://journals.sagepub.com/doi/full/10.1177/20438087231151...
Of course, I'm not an expert in anything so this could be bunk.
Spider movement is just creepy to me, even when I know where it's going. Something about the way its legs move just gives me the shivers. Even Spider-Man used to give me the creeps when I was a young child, particularly the non-speaking variant seen on The Electric Company.
I think there's just something viscerally, instinctually unsettling about how some arthropods move, which gives rise to arthropod-like monsters in fiction (xenomorphs, Bugs in Starship Troopers, Zerg, etc.). Spiders, the poor beasts, get the worst of our fear because they don't move their legs via muscles like we vertebrates, or even insects, do; their body pumps hemolymph into the legs, forcing them to straighten. This hydraulic-pressure system of movement is just different enough to our visual system to be really weird.
Big cats look adorable on a screen.
In person they can produce a different reaction.
> In person they can produce a different reaction.
A couple of years ago, a jaguar climbed from its habitat on the local zoo here, and put its paw over the fence to "play" with the humans.
A really unexplainable amount of people did not have a different reaction.
>Ancestral humans shared territory with leopards
Still do, in parts of India and some other countries, and not just where poor people live
Probably not the only one who finds spiders interesting/curious/useful but most insects kinda disgusting/ugly/dirty.
I've grown quite fond of spiders. I don't have the same aversion I used to when I was younger. There are so many hobo spiders on the exterior of my house, but I leave them be unless they're in my way, because they've noticeably reduced the populations of every other nuisance bug. As long as they keep to themselves and don't invade my space, I'll let them chill. And I just relocate them if they wander in. Killing them is just sad.
Wolf spiders are welcome in my basement though. They are smart enough and have good enough eyesight that the likelihood of getting bit by one is super low. They hunt down all the pests in your home.
What makes them extremely cool is that they're kinda like nature's hydraulic robots.
I'm with you. I'm viscerally still creeped out by spiders, but I leave them alone and let them do spider-things (which, as you say, generally involves hunting down insects that I do not want around). The same with house centipedes, which my wife wants to kill on sight but I urge her not to.
Exactly: I appreciate spiders, because they remove flies etc. I'll go out of my way to let web spiders be. I'll safely move a hunting spider out of the house. But I do not want to touch them or pet them.
Humans have even less aversion towards marine arthropods. A lot of people would find eating beetles gross, but eat gladly shrimp, and find a lobster a delicacy.
I don't think this is universal for all cultures.
Some people lost fear from other predators: aggressive dogs. They even force family members to live in dangerous situation, where they get attacked and injured regularly.
Mental illness or brain parasite is the only possible explanation for dog owners behavior.
This is definitely true, at least in the US, and it's quite different from historical norms too. Ages ago, aggressive dogs were put down quickly (or used as guard dogs, with appropriate restraints). People also didn't normally keep large dogs inside, sleep in beds with them, etc. But now it's common for some odd reason for people to want to keep aggressive dogs around their young children, and then act shocked when something terrible happens.
Even when a dog is not aggressive, unexplainable things can happen.
Last year, there was news in The Netherlands about a case where grandparents were babysitting. Their normally docile German shepherd killed the baby within seconds.
https://www-nhnieuws-nl.translate.goog/nieuws/329594/opa-en-...
Wow, some serious stupidity in this case:
>The dog had bitten another dog two years earlier and a cat seven years before the incident with the baby, but an expert stated that aggressive behavior towards animals is no reason to assume that it is also aimed at people.
Really? These "experts" are morons. German Shepherds are well-known for their use as police and military dogs because of their size, strength, and aggressiveness. Sure, they can be trained better than some other known-to-be-vicious dogs, but they're still dangerous. Putting one in a room with an infant is pure stupidity. Even worse, this particular dog had already attacked other animals in the past. At the very best, you might be able to claim that a dog that bit a cat years ago isn't necessarily unsafe around full-grown adult humans, but a German Shepherd chomping on a person isn't an immediate death sentence, but with an infant it really is.
This article also sucks because it doesn't even tell us what ultimately happened to the dog.
> aggressive behavior towards animals is no reason to assume that it is also aimed at people
Just yesterday I argued with some moron about the same thing. Obviously flagged!
https://en.m.wikipedia.org/wiki/Leopard_attack
"Attacks in India are still relatively common, and in some regions of the country leopards kill more humans than all other large carnivores combined.[9][10] "
A fascinating video of a leopard attacking baboons[1]. The big cat achieves a scratch on one baboon and then runs away from the troop. Enough to infect and then later pick off an errant victim? To my eye, the baboons are sad at the expectation that they will soon lose a friend.
> The big cat achieves a scratch on one baboon and then runs away from the troop.
It is most likely running away because it found itself completely overwhelmed by multiple attackers - it is not a hunting style big cats go for.
One crazy thing about Toxoplasmosis: Humans infected get less inhibited.
More often busted for breaking the speed limit.
More often founding a company.
Check out “The Extended Phenotype” (if you haven’t already). I think you’ll love it!
Toxo comes into the picture by way of an old wives' tale forbidding mothers from having cats around during pregnancy. Basically the only spot that toxo can reproduce itself is within a cat's stomach. The toxo then goes out with the feces (which is where the caution comes from) and rodents eat the feces. Toxo's mission is to get that rodent back into the stomach of a cat.
Rodents themselves are genetically wired to fear cats. A rat that smells cat urine will go the other way. However, get that same rodent infected with toxo and it will suddenly be attracted to the scent. Thus it checks out cat urine and becomes more likely to find itself in the stomach of a cat.
So you'd think toxo is wreaking havoc with all sorts of elements within the rat, turning it into a deranged rat. Nope. Everything else remains and functions normally - olfaction, social behavior, learning and memory, and even fear behaviors all stay the same.
It takes about 6 weeks for toxo to migrate from the gut to the brain. In the brain it forms cysts in multiple locations, but mainly in the amygdala region. The amygdala is the brain's center for fear and anxiety. It is also the brain center for forming predator aversion pathways. Once in the amygdala toxo is able to take dendritic nerve cell endings and cause them to shrivel up.
Shrivel up the dendritic spine, shrivel up the fear pathway.
Taking the creepiness up several notches, recall that other fear/anxiety based behaviors remain constant. The parasite is actually locating and unwiring the very pathway it needs to destroy.
Amazingly, it does not stop there. Toxo wants to make cat urine attractive and it is able to do so by hijacking another well known pathway; sexual attraction. Part of the neural connection for sexual activity passes through the amygdala. This gets rewired and a rodent infected with toxo will no longer have a fear response to the urine but it will have activation of this sexual response pathway, resulting in attraction to the scent.
Eau de merde. C'est fantastique! They are mapping out the toxo genome. One curious element discovered is that this protozoan parasite has two genes for tyrosine hydroxylase. This is responsible in part for the production of dopamine, which is all about rewards and the anticipation of rewards (really it's the thing that gets you to do the thing needed for the reward). It acts as a catalyst in the conversion of L-tyrosine into L-DOPA, which is in turn a precursor for dopamine.
So at the right moment, the parasite secretes the enzyme, thus driving the neurons to create dopamine at the time the toxo wants them to, thus associating dopamine with the neural pathway that toxo wants used!
Do other parasites that are closely related to toxo share this gene? No. Strangely it does not have genes for other common hormones - just this one that allows it to plug into the key for mammalian reward systems. And it starts generating it after it has penetrated into the brain and formed cysts, especially cysts in the amygdala.
For humans the current clinical dogma is that it's a disaster for a fetus but otherwise runs its course and goes latent. However, a small literature exists suggesting that males in particular become more impulsive after a toxo infection and that people who are toxo infected are 3-4 times more likely to be killed in car accidents that involve reckless speeding.
He quips that this is a protozoan parasite that knows more about the neurobiology of fear and motivation than 25,000 neuroscientists standing on each others' shoulders.
And it's not alone. The rabies virus knows how to control the neurobiology of aggression. It makes the animal more likely to bite and pass on the rabies infection.
from: http://www.robertsapolskyrocks.com/toxoplasmosis.html
https://pubmed.ncbi.nlm.nih.gov/29906469/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC117239/ https://www.mdpi.com/2077-0383/13/2/593
Martin Shkreli is still getting raked of the coals over his deraprim pricing shenanigans
https://www.ftc.gov/news-events/news/press-releases/2023/01/...
I have been fascinated by Toxo since I discovered it and this is the most well put and complete explanation I have seen.
FTA:
>Why do so few researchers study them?
>In the fall of 1985, Scott L. Gardner found himself standing over his toilet bowl, fishing around in the squishy output of his empty bowels with a chopstick.
fsckboy's law of headlines: If the headline asks a question, check if the first sentence has your answer
>...Gardner was prescribed an antiparasitic pill, and the next morning, he pooped out his intestines’ inhabitant—all 12 inches of it.
irl, my brother got a parasite once, a tapeworm. This was all without leaving an upscale suburb of Boston. Only "noticed" it when he, a well-built vigorous athlete, lost a lot of weight out of the blue. It was eating his lunch, so to speak.
> It was eating his lunch, so to speak
How does that work. A tapeworm is pretty small relative to your brother (eg by mass), one would think it's caloric needs are similarly small and it would just use a small fraction of his food. Can a tapeworm really consume a significant fraction of an adult's food?
At the Meguro Parasitological Museum [1], they have an 8 meter long tapeworm [2] extracted from a human. Yes, that is an extreme example and still less mass than a person, but they can get large.
[1] https://www.kiseichu.org/e-top
[2] Visible in the tall blue case here: https://static.wixstatic.com/media/079dcd_843c7597ef244423aa...
Bigger picture of it: https://www.tofugu.com/travel/parasite-museum-tokyo/
The display has a piece of rope, so that you can get a not-too-intimate sense of its length.
there are different types of tapeworms that infect different hosts. cattle tapeworms can grow to 12 feet and much more. It doesn't take much googling to find claims of 100 feet.
google "tapeworm symptom loss of weight" and you will get the recommendation "time to see a doctor"
So the explanation would be that growing is just very metabolically expensive and that is where the deficit goes to?
That's part of it, but intestinal parasites also interfere with normal digestive processes. Their presence and secretions (waste products and the compounds they use to prevent being digested) can cause a lot of problems. It's common for people with intestinal parasites to have reduced appetite, intestinal inflammation, and digestion issues.
The weight loss isn't just a result of the parasite competing for nutrients, though that doesn't help.
I thought of a refinement to my previous: tapeworms attach themselves to the host intestinal wall only to secure themselves; however, they feed directly from the food in the digestive tract; they do not "suck nutrients" from the host's bloodstream.
It's not a tapeworm but here's an example of a parasite that does:
https://en.wikipedia.org/wiki/Ancylostoma_duodenale
It's the stuff of nightmares.
I'm no expert on invertebrate metabolism, but it does not need to be more expensive than host metabolism, it's simply a redivision of the pizza-pie with more slices going to the growing worm, and fewer slices for the host.
consider the possibility of there being n worms in the host (person), where n is greater than 1, maybe even significantly greater than 1.
so if one worm takes m slices of the pie, and there are n worms in the person, there will be m x n less slices available for the person, which, depending on the values of m and n, could be quite high, and therefore much more detrimental to the person
Apart of eating your food directly, anything that can make you bleed internally can cause anemia.
Okay but: when he stepped on the scale, he was weighing himself and the tapeworm. A tapeworm can't just magically eat your lunch and send the calories into another dimension.
There's got to be something else to it, like that your belly feels strange and you lose your appetite.
Suddenly losing a lot of weight points toward dehydration, for one thing.
Maybe if the guy was well muscled he needed a constant influx of protein, also. Breakdown of muscle which is mostly water doesn't translate to a lot of calories.
Most athletes will probably notice if their fat content lowers or their diet doesn't bring the desired effects.
People with tapeworms visibly look like they have lost weight. They notice from the mirror, not the scale.
Not always. Plenty of people with tapeworms in them will present with few or no symptoms. If they feel anything at all, it'll probably be the usual inespecific gastrointestinal symptoms like abdominal pain, nausea and diarrhea.
Varies from person to person. Could take years before the thing is big enough to cause any real damage. I've seen cases where people had parasites inside them without noticing for what must have been decades without any treatment.
Doctors in endemic regions often won't even bother with tests, they'll treat you straight up. Good old albendazole, once a year. In certain places people routinely go to the doctor to ask them to prescribe the medicine whether they feel anything or not.
Tapeworms eating your food is definitely a very popular idea. Sometimes I see some exceedingly clever humans trying to use them as a poor man's semaglutide. They usually get zero results but sometimes they lose some serious weight alright, most of it water.
I recommend the funny and gross book, "New Guinea Tapeworms and Jewish Grandmothers: Tales of Parasites and People" by Robert S. Desowitz. Basically a bunch of horrible parasite diseases, some with a bit of detective story to figure out.
TWiP: This Week in Parasitism A podcast about the tiny creatures that live on and inside us. New episodes the 1st and 3rd Friday of each month.
If you're ever in Tokyo, the Meguro Parasitological Museum is genuinely worth a visit although maybe don't go straight out for sushi afterwards as we did.
Pictures of parasites: https://www.atlasobscura.com/places/meguro-parasitological-m...
Now you’ve got me curious… are parasites part of any culture’s diet? I’m assuming human parasites are a hard no since it’d be like mainlining the eggs, but are there any parasitic species that we eat? There’s probably more plant ones like huitlacoche but I can’t think of any edible animal parasite.
I know there’s Ophiocordyceps sinensis which attacks caterpillars but that’s more traditional medicine than food.
Here are some examples of parasites that are purposely eaten by humans:
https://www.smithsonianmag.com/smart-news/five-parasitic-spe...
Bécasse paté with tapeworms in France ??? I m french and never Heard of this. And I can't find anything in french about this on internet. I'm sceptical...
I asked a French friend who comes from a long line of hunters. He'd never heard of it either. There are quite a few French woodcock preparations that include eating the guts, but I've never heard anything about tapeworms. I've also cleaned quite a few American woodcock, and I have never seen a tapeworm in the innards.
I think you mean parasites that we purposefully eat, but there are parasites everywhere. If you eat raw, or cooked fish, there's a reasonable chance you've eaten (hopefully dead) parasites. But not all parasites are harmful to humans, so you tend to hear less about those.
There's an excellent answer already, but I would like to add mushrooms, since some of them are parasitic (eg ones that grow on trees). So I think: shiitake mushrooms.
The mushroom that grows in ants are parasitic and scary.
Which itself gets parasitized by other fungi
Perhaps because we have probably already discovered pretty much every parasite that infects humans, at least those with widespread impact in the western world?
Parasites tend to be multicellular and relatively large (you can see them all with an optical microscope), and therefore hard to miss.
On the other hand, there are plenty of bacteria and viruses that are out there still to be discovered, many of which directly impact humans.
> Perhaps because we have probably already discovered pretty much every parasite that infects humans, at least those with widespread impact in the western world?
The thing is, discovering them is not enough, not by far. We know how to avoid a few of them - say, by washing hands, regulatory agencies requiring meat be controlled for parasites (in Germany and possibly EU, against trichinella [1]), or by heavily suggesting pregnant people not handle cat litter (to prevent toxoplasmosis). We know how to treat a few of them (mostly worms).
But we don't know how to treat a lot of them, for some of them (particularly in the veterinarian world) we're dealing with resistency developing. And a few of them remain utterly and completely deadly (Naegleria fowleri).
The problem is, as always, a lack of funding. No one wants to spend much money on parasitology (as you said: we know about most of them), and since most parasitic infections are rare in Western countries that have the money, there is not much money for treatment R&D - no matter how many people die each year worldwide (400k for worms, 600k for malaria alone).
Malaria in particular is a target of constant attention. Latest breeds of generically modified mosquitoes are unable to carry the disease [1] or that turn the carried mosquito populations infertile [2]. I'd say that malaria will be eradicated in 30-50 years. Hopefully, Guinea worm will be eradicated, too [3].
Neither malaria nor Guinea worm affect "Western" (rich, industrial) countries directly, but people from these countries most actively work on the eradication, chiefly financed by charitable funds.
[1]: https://www.imperial.ac.uk/news/239931/mosquitoes-that-cant-...
[2]: https://www.nature.com/articles/nature.2015.18974
[3]: https://www.cartercenter.org/health/guinea_worm/index.html
Is that true that most parasites are multicellular? My intuition would suggest that single celled parasites would be more numerous, even if they are less clinically significant. Malaria is one of the most significant diseases in the world and it's caused by a single celled parasite, for example.
I've often thought that the economics profession could do with more cross pollination with biology. Modeling the economy as a living ecosystem with, for example, a network of parasites and symbiotes would be more illuminating than the default neoclassical mode that almost treats it like a sanitized gaseous system where you turn a dial labeled "interest rates".
I'm pretty sure there's a lot of conceptual overlap between parasitic/symbiotic organisms and economic relationships, too. E.g. I'm pretty sure this kind of thing happens all the time in scamming ecosystems:
>Often, in an effort to travel between host animals, parasites will expose their hosts to new predators, like the tapeworm Ligula intestinalis, which grows so large it changes the buoyancy of the fish it inhabits, causing the fish to swim closer to the surface and get eaten by birds.
It has been, it’s a field called sociology. https://youtu.be/exPOPm8qQsY luhmann has something in it called systems theory.
Sounds cool, if you can define economic "symbionts" and "parasites" in a rigorous way I'm sure it would make an interesting blog post.
I don't disagree with you but economists are well aware of economical parasitism. (rent seeking, negative exernalities, game theory etc etc)
The whole point of the field of economics is not as popularly believed to shill neoliberal, neoclassical free markets, it's kind of the opposite - to study all the ways in which economics models (and markets in general) fail (both in the abstract and in the real world) and how to fix that. (and the solutions have been known for decades at this point, but policymakers don't implement them)
>The whole point of the field of economics is not as popularly believed to shill neoliberal, neoclassical free markets
At least half of it is, and that's where the money and prestige generally is. There's plenty of elaborate mathematical models being created by PhDs and postdocs relying upon neoclassical economic axioms.
I don't disagree that economists are in theory aware of economic parasitism I just think that it's one of those topics where research funding can often end up in weirdly short supply.
> I just think that it's one of those topics where research funding can often end up in weirdly short supply
this simply isn't true, go actually look at what economists are doing and you will find these issues are getting studied and taught a lot, it's basic stuff
great idea, why don't you follow it?
It is in fact a good idea, and it would probably generate a lot of insight. But it would be very politically dicey.
Someone did a book like the Secret Life of Trees but just for Oaks. There are a thousand critters and microbes adapted to oak habitation and/or parasitizing.
The tannins in oak are an arms race to slow many of them down. As is the thick epidermis on mature leaves. And then there are the adaptations to prioritize roots over leaves when young, which both helps them tap into the wood wide web but also I suspect helps them deal with deer. Stay small until you can get tall and then jump out of reach as fast as you can.
I immediately Ctrl-F'd for 'funding'. There's your problem right there. If there's no money to support graduate students, you're never going to get enough researchers to replace the ones you have.
Additionally, graduate students tend to avoid selecting research areas they dislike or find disgusting. The most disturbing presentation I've ever watched was a slideshow given by a parasitologist in which I saw worms in parts of the human body I never imagined it possible for worms to be in. No wonder students aren't lining up to spend years of their life working with them.
> The most disturbing presentation I've ever watched was a slideshow given by a parasitologist in which I saw worms in parts of the human body I never imagined it possible for worms to be in.
I read an essay once by someone who intentionally incubated some kind of fly in himself, and wrote that, after all the effort of being infected and incubating the fly, it chose to emerge while he was at a baseball game, where, he lamented, it was immediately killed by horrified fans over his protests.
The fans were clearly in the right.
Parasites are neglected tropical diseases. That's an euphemism for "third world shithole problems". These things aren't much studied because there is no actual need to study them. They are solved by civilization.
Developed nations solved parasites naturally as they developed. Infrastructure, basic sanitation, standards for food production... All of these things interrupt the natural fecal-oral lifecycle of parasites, solving the problem.
Naturally, developing nations are terrible at all of those things. To put it mildly. And thus parasites are endemic. They are literally every day things. It's actually kind of surreal.
It doesn't matter how much funding people put into parasitology, it doesn't change the fact the true solution is to develop the nation into a proper civilization.
During the most disturbing* presentation I ever watched, the simultaneous translation went dead for a good 15-20 seconds; I assumed the translators had muted their mikes to cover the dry heaves?
* one could always spot the reconstructive surgeons at these conferences; they were the ones who could wander around the poster session, all while calmly nibbling away at their hors d'oeuvres.
The best way to get funding is for your idea to either have economic potential or to be politically useful. Both of those outcomes generate power. Ideas that don't generate power go to the back of the line when it comes to funding.
There's not much profit in treating parasites, and profit funds research. Like bacterial infection (before the rise of resistant bugs), you treat a parasite with a few doses and you're done. No more disease means no more revenue. So unless a really large fraction of the high income world gets a parasite, or the parasitism is chronically incurable, there's too little financial reward to justify studying or treating it.
We can acknowledge the effects on rat sexual arousal, but to extend this research into human behavior is just asking to get your funding cut and be excommunicated.
If parasites were widespread amongst human beings, would those infected humans have incentive to study them?
We are likely biased and can't imagine how we are biased because of the infection! Yet the over-under for an individual is clear: try the medication and find out!
>> would those infected humans have incentive to study them?
Plenty of diseases get us and most of us don't have an incentive to study what we know is statistically likely to kill us :<< . Which I think is a shame.
Generally research follows funding, not intellectual curiousity. So the single-celled eukaryotic malaria parasite is pretty well-studied. This also highlights the often arbitrary nature of division of labor in academics - all viruses and many eubacteria could reasonably be classified as parasites, but are instead handed off to virology and infectious microbiology (which tends to exclude parasitic eukaryota, even single-celled protists, from its domain).
Out in nature, things get more complicated - there are many reports of viruses infecting parasites which in turn infect animals, for example.
https://schaechter.asmblog.org/schaechter/2011/07/viruses-th...
The tradition in parasitology of self-experimentation -- swallowing unknown larvae to see what they do to your body -- perhaps might deter new recruits from entering the field.
In my (hobby) field of artificial life and program generation, there is a lot of research into the energy dynamics of parasitism.
Isn’t there a lot of parasitic research at DARPA facilities, for example Lyme disease and Rocky Mountain spotted fever?
I think Lyme disease is caused by a bacteria rather than parasite (I always assumed the two are different)
Yeah, maybe ticks are the parasite in that scenario
I understand that the question here is why nobody studies parasite biodiversity.
Well, this is a false claim. Sort of. Nobody notices or nobody cares about this researchers, is not the same as nobody studies.
This should be some interesting discussion since parasites are kind of the hackers of the biological world.
I thought that honor belonged to viruses.
Viruses are a kind of parasite.
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because they're oh so disturbing
the same reason why so many other disturbing things go unstudied
like certain risks to our survival, for example
i think it's a vuln humans have
>Why do so few researchers study them?
Because they're the ones funding medical research! nyuk nyuk!
Seriously though, as a health nut who tries to stay on the science side of things, I still see a lot of "It's Parasites!" stuff from the pseudo-science health community. As well as bizarre cures. Walnuts, Cloves and electric shock seem to come up the most.
I have tried to find any practical advice regarding detection, symptoms and such, and beyond tapeworms, heartworms and hookworms, there isn't much information.
The amount of grants that you receive in modern zoology is directly proportional to the sweetness in your discourse, the size of the eyes and the density of the fur in your subject
> Housed in a few modest rooms adjacent to a botanical collection and the floor’s only bathroom, the laboratory is the world’s largest university collection of parasites.
> the Manter Lab only receives enough funding to employ the two men
This explains why perfectly. Researchers that choose this live basically in poverty, so why would you to encourage your son to follow that career?.
This and the two billions of videos of cats on internet that everybody consumes actively all the time. Try to earn sympathy and views with a samba dancing flatworm compilation instead. It only works one or none times.
Maybe we could try a hybrid pitch? “We need to protect these cute, furry little dudes…from parasites. Giv money pls.”
"Parasites evolved for millions of years in this planet have exactly the same right to exist and to be saved as any other earthlings. Stop hitting me just because you don't like the truth, please". More realistic.
They are a big part of earth biodiversity and provide services to the ecosystem or the host. Services that sometimes no other can provide. Some parasites can clean in theory the host body of poisonous mercury. Could we train parasites to eat cankerous tumors in the future?
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This seems highly personal.
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Many mathematicians would get offended if you suggested their work has practical applications.
Most mathematicians don't need much in terms of funding. They don't use expensive sequencers, fancy electron microscopes, lasers, particle accelerators etc. Maybe a timeshare on a compute cluster and some disk space, if that.
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