i believe perhaps it can but there are many times where it wouldnt and just "take hold"
there are 3 or 4 different fungi types that can cause ringworm so perhaps its dependent on which strain thats the cause as to whether it goes on its own ir not, i'm sure that the microsporum canis is the most common one. Also after fraser having it i learned that some cats can also be carriers of it even though they dont show any signs or symptoms.
I got rid of mine on my arm fairly easily but hubbys patch on the back of his shoulder seemed to take the best part of a year with continued canestan use, i even put tincture of iodine on it. It did seem to go initially but left a faint red mark on the skin which used to sometimes look more active than other times (was never bigger than a 50p coin). Fraser i was convinced was one of those carriers as the main area where he had it seemed sparser in hair and would sometimes look abit "moth eaten" altho he never had full blown break outs.
He hasnt actually looked like he's had any reacurrence for a long time now though & dh not had any signs for years either but it certainly seemed a lingering one. I never had reacurring problems nor did any of the other animals get it (mind you i didnt have them at that point
).
In cattle it obviously spreads like wild fire and is very common, normally they all get treated but any that seem weaker or are ill often have it worse.