Ringworm is occasionally encountered in the clinic, mostly due to fungal infections in cats after keeping them at home, which are then transmitted to people. To determine whether a person has ringworm, you can look at the following aspects: 1) you have a cat at home or have been in contact with a cat; 2) ringworm appears on the skin as annular erythema, which expands outward eccentrically and is bright red and itchy; 3) ringworm is self-infectious, meaning that a person who has ringworm in one area may have it in other areas of the body; 4) a fungal microscopy reveals mycelium or spores You can be sure that you have ringworm.