Q. Why do I keep getting athlete’s foot? Why don’t we become immune to it, like we do against other infections?

A, Because the fungal infection is in the dead layer of the epidermis, your ‘outer’ skin, where there are no blood vessels to carry the immune system’s defences to it. So we don’t build up long-term antibodies to the fungus, and if we did they couldn’t reach the skin surface to destroy it.

Maybe our bodies haven’t yet found a way of destroying it. Evolution hasn’t made us perfect.