Ringworm in humans is caused by

Ringworm refers to fungal infections that are on the surface of the skin. Although the world is full of yeasts, moulds and fungi, only a few cause skin problems. These agents are called the dermatophytes. Some common dermatophytic fungi are Trichophyton rubrum, $T$. tensurans, $T$. interdigitale, $T$. mentagrophytes, Microsporum, Canis and Epidermophyton floccosum.