Many types of fungal germs (fungi) live harmlessly in the soil, on food, on our skin and in other places in the environment. However, some types of fungi can thrive and multiply on the surface of the body, to cause infection of the skin, nails, mouth or vagina.The most common fungi to cause skin infections are the tinea group of fungi. For example, tinea pedis (athlete's foot) is a common fungal infection of the toes and feet. A common fungal infection of the mouth and vagina is called thrush. This is caused by an overgrowth of candida which is a yeast (a type of fungus). Small numbers of candida commonly live on the skin. However, certain conditions can cause candida to multiply and cause infection.