Trichophyton rubrum is a fungus that infects humans exclusively and is not found in the natural environment. As humans evolved, it spread from East Africa to all corners of the world, spreading Trichophyton rubrum wherever people with tinea pedis or tinea cruris moved. Trichophyton rubrum grows with humans, and as humans come into contact with each other in their daily activities, both directly and indirectly, Trichophyton rubrum is transmitted to each other through contact with people’s daily behavior, one to another, one to ten, ten to a hundred, and the number of infections grows. In warm and humid places, Trichophyton rubrum is more contagious and spreads more easily, so it is less common in the north than in the south, and less common in winter than in summer.