Ringworm infection on the arm of a 20 year old female. Ringworm is a disease caused by a fungal infection of the skin. It can be caused by various fungi, including Microsporum sp. and Trichophyton sp.. The main symptom of ringworm is a rash that may be scaly, dry, swollen and often causes severe itching. The disease is highly contagious and can be spread by direct contact or by contact with contaminated material. Treatment is with antifungal drugs.