Where I live, we get more hours of sunlight than most of North America. We see ringworm on occasion on pastures and one of the remedies is " sunlight"... Go figure. It only appears once every several years so it is hard to understand what set of conditions allows for ringworm to raise it's head and attack. I have never seen a cow get ringworm more than once in it's ife. I have had it more than once myself, so I am thinking that humans do not develop the same immunity. All I know is, if it is as painful for a calf or cow to have ringworm as it is when I get it, this would certainly reduce gains and increase stress on the animal.
Last winter, I found a spot of ringworm on my arm. I immediately went to my doctor and he gave me some medicated ointment to put on it. I tried to tell him that I had never had any luck killing the ringworm with this stuff before, but he said it was the best thing available( I usually give my doctor the benifit of doubt that he is smarter than me, but I really don't think he is a " ringworm expert".) After a few days of faithfully using the ointment, I could see that the ringworm was still growing rapidly and was now several times larger than when I had first found it. I made an" executive decision " and went to the show box and brought out the bottle of Sullivan's Fungus Fighter. I soaked gauze in it and put it on the ringworm and covered it with a large bandage. It stopped growing immediately and was completely dead in 3 days. Now kids..... don't try this at home. Just because I didn't die doesn't mean you won't.... Come to think of it... maybe that was what made my hair disappear!