Otherwise, do you mean what do you do about them being there? That's a tough one. I am not sure what the solution would be. The standard solution on a farm or ranch is just to treat the animals (or people) I think, not the soil.

Normally, I'd say beneficial nematodes, when used at the time of year when temperatures are favorable, would help, but I've never seen thread worms referenced in any way when reading about beneficial nematodes. There's probably beneficial microorganisms that, when added to the soil, might destroy the thread worms but I don't know how you'd find out what they are or where to purchase them, if they even are available commercially.

If it were me, I'd probably contact my local county Ag Extension agent for advice, or contact OSU, likely through the Soil, Water and Forage Lab, to seek their advice. If that route was not fruitful, I'd probably contact the Ardmore-based Noble Foundation to see if one of their soil or rangeland scientists could suggest anything.

Generally, when you have any sort of pest infestation that lives part or all of its life in the soil, the standard method of dealing with them is to add organic matter and other substances like humates and dry molasses to your soil in order to increase biological activity in the soil. Generally as the soil gets healthier and more biologically active, the microorganisms in the soil take care of the pests.

You also might try asking this on the Soil and Compost Forum to see if anyone there has tried to remediate soil infested with thread worms.