What is the common name of the contagious infection caused by a fungal agent?

The common name for the contagious infection caused by a fungal agent is ringworm. This skin condition is actually a type of dermatophyte infection, which is primarily caused by fungi that infect the skin, hair, and nails. Ringworm can easily spread from person to person or through shared objects such as towels, clothing, or athletic equipment. Its characteristic round, red patches with clear centers give it the appearance of a "worm" under the skin, although there is no literal worm involved.

Athlete's foot is also a fungal infection, but it specifically affects the feet and is not as broadly contagious as ringworm. Shingles, on the other hand, is a viral infection related to the varicella-zoster virus, which causes chickenpox, and is not caused by fungi. Psoriasis is an autoimmune condition that leads to rapid skin cell production but is not an infectious disease, whether fungal or otherwise. Thus, the identification of ringworm as the correct answer ties directly to its nature as a contagious fungal infection.