Having battled the worm many times, here's what I did to get rid of it and I suggest it to anyone who has it in their tanks.
First off, this is a very hardy parasite and very hard to kill. It takes more than treating the tank, the fish have to ingest the meds to kill off the worm.
Levamisole or fenbendazole both are good meds. I use fenben myself but have heard good thing about leva.
Get frozen, not freeze dried, blood worms (all fish love blood worms). Put a cube (or two depending on how many fish you are treating) in a non porous dish, like a coffee cup. Let the cubes melt and add some of the medication. Let the blood worms soak up the meds for about half an hour. Feed the fish this twice daily until you see the parasite change color. The blood worms will turn color too while soaking up the meds, that's fine.
After the first 2-3 feeding, you will notice the worms in the fish turning gray/brown. They aren't dead yet, but are pretty much paralyzed. The fish will start pooing them out. Since they are still alive, they get into the tank. Do a good water change and gravel vac. Get some Jungle Anti-Parasite fizz tabs and use them at half strength over a longer period of time.
Example; the package says use 2 tabs per 10 gallons, 30 gallon tank, for 3 days, that would be 18 tabs. To avoid stressing the fish out more because of the meds, use 1 tab per gallon for 6 days.
After the first round of fizz tabs and medicated food do another water change and vac cleaning. Wait a day or two, then start the whole process over.
The first process is mainly to weaken the adult worms and try to kill any eggs/young that they have produced. The second round is to get rid of the rest of them. You can do it a third time if needed, just be sure to do water changes in between.