I worked on a drug program against a pathogen that was transmitted as spores. Basically the treatment was given when there was a flare up, because the organism was only vulnerable in that mode. We tried killing the spores themselves but evan at toxic-to-human doses the spores didn't give a shit. So people would get better, then have further outbreaks.
Note that from a drug company's perspective, this is actually pretty great. You don't treat them for long enough that it's considered a "chronic condition" from a regulatory perspective (which would mean much more complex trial protocols) yet you know if you treat anyone you'll have a repeat customer, probably for the rest of their lives. But despite public opinion of pharma companies, I never heard anyone say "thank you spores!" In fact we did continue to try to attack the spores.