The explanation for nail fungus contamination is almost always one of a little number of fungi along with yeasts that are equipped for pulling diet via keratin, a new healthy proteins present in nails, or of invading the gentle muscle round the toenail. The most general causes of fungal nail infections are a fungal skin infection or damage to the nail or skin. A fungal infection in the toenail is often caused by a fungal skin infection such as athlete’s foot. About a third of people with athlete’s foot also develop a nail infection.