But with a new discovery published in the journal Nature Neurosciene, Peden can chalk one up against the parasites.
For the study, the postdoctoral fellow at the University of Utah and several co-authors explored one of the traditional methods of protecting plants from the worms: drenching them in seaweed extract.
They found it works because seaweed contains the compound betaine, which overloads the worms' movement neurons. Their bodies hyper-contract, become paralyzed and they die.
The results could help create better drugs for resistant worms and perhaps one day help us better understand our own brains.
The study "potentially identified a new neurotransmitter," said U. biology professor Erik Jorgensen, one of the co-authors in the study. "These are the things that make our brains work."
Though the researchers haven't demonstrated betaine is a neurotransmitter, it's already known to be present in the human brain, where it's involved in suppressing seizures. Betaine functions like other well-known neurotransmitters, such as the pleasure-transmitting dopamine, Jorgensen said, raising hopes it could be another key to brain function.
"We know that it's something a neuron responds to in a rapid way," he said. "We don't know if it's something neurons [are producing]."
If betaine is found to be produced by neurons, it could open the way for new discoveries about how the human brain functions.
In the meantime, though, Peden's findings could help develop new drugs to fight parasitic nematodes. Though there is already a drug that works in the same way seaweed does, that's not a panacea.
"The major problem is there is always resistance," Peden said. "A few years later, there's a new strain that can survive, and it's usually more dangerous. You have to find new ways of killing the worm."
Gastrointestinal nematode infections among humans don't appear to be abating the infection numbers haven't changed much in the last 50 years, according to the Journal of Experimental Pathology paper, which says public recognition and research funding has been neglected.
Peden's work not only identified a pathway by which the betaine enters the nematode cells to overwhelm and kill the creatures, but it also found another protein mutation that makes the creatures impervious to the effects, which could help scientists overcome that immunity.
"I think [Peden's] personal experience makes it much more motivational," Jorgensen said. "She really figured out this problem, and at the end it was a surprise. So many cases in science you end up chasing something and you don't know where it will lead, but when you get there it opens up a whole new area of fascinating new work."