I've kept snakes for 10 years and been breeding them for 8. I never had a problem until this year. They came in with a baby ball python. I checked her, had her slither through my hands, checked my hands, quarantined her for a week. No mites, no sign of mites, and then bam! Mites on her, mites in my rack, and they spread. I thought I had them beat 2x and then finally I got them. They can be hell to get rid of. Especially for someone like myself that has asthma. I can't use certain sprays because they'll induce an asthma attack. I did find that soaking the snakes in soapy water for 6 hours killed the ones on them. Next I soaked them in water with Nix,1-2 hrs. Nix is the stuff you can get at the local drug store for head lice, crabs, etc. I also mixed an ounce of the liquid Nix soap into a quart of water. I sprayed down my rack and all the boxes. then every other day I would spray some of that mix on a rag and have each snake slide and slither through it. I did that for one week. That worked best for me. Just one word of caution, do not soak a snake that is in the blue. During their shed cycle they go through a process of absorbing moisture. This is that time, a day or so before they shed, that their eyes are suddenly not blue, they have cleared up. They can absorb too much of the treatment and die. I unfortunately read about this after the fact.
Best of luck
John Q