as HTML Detailed information on the most common types of ringworm, including diagnosis and treatment. Ringworm is usually a mild fungal infection of the skin that causes a red circular lesion with a scaly border. I've got a strange rash on my leg, which my doctor's told me is ringworm, and which I'm treating with a cream. What is a ringworm, and how did I catch it? Although it is best known as an infection that cats and dogs get, ringworm can also infect humans. At any given time, at least 20% of the population will be ... Ringworm is a skin disease caused by a fungus (plural: fungi). "Because the lesions are often circular, ringworm was once thought to be caused by a worm ... Ringworm is one of the common skin diseases. The disease is caused by a fungus,