Sykaran worms were rare parasitic organisms that developed on the planet Sykar. When the Sykarans began to be enslaved by the chemicals in the tannot root, however, it was discovered that they had a use. Sykaran worms, when attached to a hosts digestive system, could filter out the mind altering effects of the root and render the host free from brainwashing. As such, as the Sykaran Resistance -- begun by those with a natural immunity -- began to slowly expand their numbers by passing the worm along to others. Possession of the worms, like the natural immunity, was a criminal offense punishable by death.
The worms were easy to remove from their hosts, although the process was known to be extremely painful.
Source[]
Sykaran worms are derived from Farscape.