Nail fungal infection is usually caused by a fungi that belongs to the dermatophyte group, but certain types of mold and yeasts can also cause nail infections. Nail fungal infections, also known as tinea unguium and onychomycosis, account for 50 percent of all known nail abnormalities, according to Medical News Today. This medical condition also appears more often on the toenails than on the fingernails.
In most cases of nail fungal growth, the dermatophyte fungus Trichophyton rubrum is the cause of the infection. However, other dermatophyte fungi such as Trichophyton tonsurans, Epidermophyton floccosum, Microsporum gypseum, Trichophyton interdigitale and Trichophyton violaceum may also cause nail fungal infections. Among the mold species that may cause nail fungal growth include Aspergillus, Neoscytalidium and Scopulariopsis.
The symptoms of nail fungal infection as listed by Mayo Clinic include thickened nails, which are also crumbly, ragged and brittle. The nails may also look dull, distorted and have a dark color due to the fungal debris that accumulates between the nail and the nail bed. Nails may also lift from the nail bed, emit a foul odor and cause pain on the infected toes or fingers.
Men are more prone to develop nail fungal infection compared to women, and the condition is more common among the elderly. Among the factors that increase the risk developing nail fungal infection are poor blood circulation, family history of fungal infection and a weak immune system response.