I spread mine and don't have a worm problem. I have a fecal count test done regularly (I don't like to worm if I don't have to) and they have always been wormless.
I do compost my winter manure and harrow the summer pasture manure regularly to keep it broken up. We have hot dry summers here, if I was a worm I wouldn't live in it
its usually just dust. I release fly predators and maintain massive amounts of fly traps in summer so we don't have much of a fly problem either.
"Until one has loved an animal, part of one's soul remains unawakened..."
- Anatole France