Fungi cause three different types of human illness: poisonings, parasitic infections, and allergies. Many poisonous mushrooms are eaten by mistake because they look like edible mushrooms. Parasitic yeasts cause candidiasis, ringworm, and athlete's foot.Tinea corporis or ringworm is a skin infection caused by a fungus that lives on dead tissues, such as the skin, hair, and nails. Ringworm is the fungus that causes both jock itch and athlete's foot. When it appears anywhere else on the body, the infection is just called ringworm.ungal skin infections can happen anywhere on your body. Some of the most common are athlete's foot, jock itch, ringworm, and yeast infections.Apple cider vinegar has demonstrated antifungal properties against Candida, another fungal infection. To treat ringworm with apple cider vinegar, soak a cotton wool pad in the undiluted vinegar and wipe it on the affected area. Repeat up to 3 times daily.