The worm that tells a toad how to poop

Behold another example of the ickiness of nature, via Joerg Fliege.

Scientists recently discovered lungworms alter the behavior of their cane toad hosts to ensure things are most comfortable for them. But what is surprising, or at least a little unnerving, is what they actually do: the worms makes their hosts poop differently.

“We found that toads with lungworms behaved much differently than uninfected toads is several regards,” explained Greg Brown, a research fellow at the University of Sydney and co-author on the paper. “Most notably, infected toads tended to stay closer to water and poo in moister areas. These are the conditions that increase survival of the larval worms in the poo and increase their likelihood of encountering a new host.”

It’s possible that these behavioural changes are the result of an immunological assault, but the researchers think this is unlikely. “The fact that infected individuals act differently than uninfected ones isn’t that surprising,” Brown continued, “but the nature of the differences seemed to consistently be in directions that that should favour parasite fitness. That’s why it appears to be manipulation rather than just general sickness.”

And if so, then the results open a, well, can of worms, so to speak, because they are evidence that parasitic manipulation of hosts may be more subtle than scientists thought—and more common. “Lots of parasite larvae are transmitted to the environment through feces, so maybe parasite ability to manipulate host pooing is widespread,” said Brown. “It seems like a logical way for the parasite to increase the likelihood of its offspring surviving and infecting another host.”

http://blogs.discovermagazine.com/science-sushi/2018/04/28/lungworms-maipulate-cane-toad-bowels-feces/