How parasites manipulate hosts

December 5, 2012 • 11:52 am

If you want to see the latest scientific skinny on how parasites manipulate hosts (e.g., the fungi and flukeworms that turn ants into “zombies”), you can’t do better than read this special issue of The Journal of Experimental Biology: “Neural parasitology: how parasites manipulate host behavior.” And all of the articles are free!

I’m always amazed that so-called “simple” organisms like fungi and flukes can affect host behavior in complex ways that facilitate the parasites’ reproduction. This is one of the great unknown areas of biology that will eventually yield to patient investigation.  What chemicals do they produce that can, say, force an ant to climb a tree trunk, dig its mandibles into the trunk, and at the same time turn its abdomen red (like a berry) and weaken the junction between abdomen and thorax, so that a hungry bird will spot the parasite-filled abdomen, mistake it for a berry, nom it, and then allow the parasite to continue its life cycle in the bird’s digestive tract? There must be interesting chemicals involved! You can read about that story here, and here’s the unfortunate ant:

A parasitie nematode has killed this ant but also changed it to make its abdomen resemble a berry, facilitating its ingestion by the next host, a bird
A parasitic nematode has killed this ant but also changed it to make its abdomen resemble a berry, facilitating its ingestion by the next host, a bird

But there are many other cases like this. Here are a few of the JEB articles with links, but see the full table of contents for more.

 HOW PERNICIOUS PARASITES TURN VICTIMS INTO ZOMBIES
Kathryn Knight
J Exp Biol 2012 216:i-iv. doi:10.1242/jeb.083162

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Editorial
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 Neural parasitology: how parasites manipulate host behaviour
Shelley A. Adamo and Joanne P. Webster
J Exp Biol 2012 216:1-2. doi:10.1242/jeb.082511
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Alteration of host behaviour
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Parasites: evolution’s neurobiologists
Shelley Anne Adamo
J Exp Biol 2012 216:3-10. doi:10.1242/jeb.073601

An overview of parasite-induced behavioral alterations – and some lessons
 from bats
Janice Moore
J Exp Biol 2012 216:11-17. doi:10.1242/jeb.074088

Parasite manipulation of host personality and behavioural syndromes
Robert Poulin
J Exp Biol 2012 216:18-26. doi:10.1242/jeb.073353

h/t: Matthew Cobb

25 thoughts on “How parasites manipulate hosts

  1. For anyone interested in parasites, I highly recommend Carl Zimmer’s “Parasite Rex.” Actually, even if you’re not interested. I will never look at the world the same way again. Or snails.

          1. It’s OK. Just don’t post with the http in there, or it will enbed the video. If you leave the http out, it does not embed, but it puts the http in there, making it clickable. This is all fine and dandy. Ya did good.

  2. Are there common, i.e., not criminal, behaviours that we display due to manipulation by parasites? (If the induced behaviours were too obviously criminal, parasites’ hosts would be locked up or executed – not good for their reproduction.)

    1. Generational indoctrination into woo-ish belief systems? 🙂

      The parasitic meme persisting because of a need by the majority for certainty, social acceptance & an overarching purpose to life on one hand & the drive for the accumulation of status, wealth & power by a manipulative few on the other

    2. Toxoplasmosis gondii could possibly instill an extraordinary fondness for the kittehs… it certainly causes rodents to lose their fear of them. Excuse me, I must go change that lovely catbox now.

    3. I’ve read that Toxoplasma gondii from cats changes human behaviour in such a way as to promote the spread of its own genes ~ but it was a pop-science article…

      I’ll await debunking by the catxperts

      I also considered if Kuru could fit your bill, but I don’t think so. Unsure.

  3. For that kind of host-manipulation to be so effective, there must have been many, many behavior modifications that didn’t work to the parasite’s advantage. I wonder what human behaviors are directed by parasites that are neither harmful or beneficial? Could gut bacteria control our food cravings by mimicking hormones as efficiently as a need for the human cells?

    1. I wonder what human behaviors are directed by parasites that are neither harmful or beneficial?

      many others do too.

      check out the papers on toxic plasmosis.

    2. Here’s a starting point for toxoplasmosis, which *may* affect dopamine chemistry in humans: en.wikipedia.org/wiki/Toxoplasmosis#Behavioral_changes

      I can’t think of other pathogens affecting behavior in humans – esp. doing so in neutral ways. Only other thing that comes to mind is rabies negatively affecting behavior in rodents, skunks, etc., causing them to go apeshit and want to bite, or affecting their normal sleep patterns… nocturnal critters going out in the daytime where they interact with other critters they wouldn’t normally interact with. That kind of thing.

  4. “How parasites manipulate hosts”? With a title like that I thought this was going to be a post about religion and society. Disappointed!

  5. Over the years, I have read several papers about changes in fish behavior after low, sub-lethal exposure to pesticides or heavy metals. I’ve also read papers on parasite induced modification of fish behavior. I was struck by how similar the effects were; all producing behavior which would make the fish more vulnerable to predation.

  6. I had often wondered about bacteria causing behavioural change: specifically, it used to strike me that one would expect STDs to spread more rapidly if they led their ‘hosts’ to copulate more.

    For Christmas I received a copy of ‘The Man Who Mistook His Wife For A Hat’, and lo and behold one chapter refers to an old Greek lady who reported feeling ‘frisky’ to the doctor and made the connection with a flare-up of the syphilis she had contracted as a young woman working in a brothel.

    I guess this is well-known, but it made me feel quite proud of myself!

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