THE NEXT TIME you’ve got something to complain about, consider the plight of the intestinal worm. It not only has to figure out how to eat and breed in the confines of another creature, it has to prevent that creature’s body from dissolving the parasite into a mist of cells. That means dodging the immune system and inflammation, the body’s natural responses to invasion. Meaning, your late car payment ain’t got nothing on spending your entire life in an intestine.
Researchers at the University of California, Riverside, have found that one nematode worm, Nippostrongylus brasiliensis, appears to boost its odds of survival by dosing its rodent hosts with endocannabinoids, molecules that are known to reduce inflammation. (The cannabis plant, of course, produces cannabinoids as well.) All the while, the host is releasing its own endocannabinoids, seemingly to dull the pain of the worm’s infiltration, creating a double dose of painkillers in the mouse’s body.
It’s a hell of a finding for parasitology, and even more promising for the treatment of parasitic worms in humans. Because it turns out that the same genes regulate endocannabinoids in our invaders as in the worms that infect rodents—meaning they could be dosing us as well.
The endocannabinoid system is highly “conserved,” meaning it evolved long, long ago before the ancestors of these worms and mice went their separate ways on the tree of the life. Science is just beginning to explore the system, but it appears to have many functions: It regulates appetite, mood, and memory and serves as the landing strip of sorts for molecules from the cannabis plant.
Now, a mouse loaded with Nippostrongylus brasiliensisis an unfortunate mouse indeed. The parasite gets in by burrowing through the skin, then riding in the bloodstream to the heart. From there it’s pumped to the lungs (the first stop for blood, since the body needs to oxygenate it), where the worm grows and burrows into tissue, leading to inflammation and damage. The mouse will then cough up the worm and swallow it. The parasite travels to the intestines, where it gnaws on tissue, breeds and releases its eggs to be pooped out and hatch into baby worms and infect still more mice.