I think using a flame thrower for salpingitis is overkill, pardon my expression. Wouldn't you want to just isolate those infected, treat them with antibiotics, then disinfect the coop with bleach, vinegar, Odoban, etc.?
The OP was dealing with something unknown, so it could have been one of...
Hiya, and welcome to BYC!! :frow
There's a product called Odoban you can use to wash stuff and it kills Marek's in addition to just about everything else.
The dirt is a problem too though and I doubt you can use it for the dirt. If you did, it'd probably kill everything, but then I'd not...