What Is a Nail Fungal Infection? What Causes Nail Fungus Infections?

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Main Category: Dermatology
Also Included In: Infectious Diseases / Bacteria / Viruses;  Sports Medicine / Fitness
Article Date: 29 May 2009 - 9:00 PDT

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Also known as onychomycosis and tinea unguium, nail fungal infections are the most common diseases of the nails, making up about 50% of nail abnormalities. Both fingernails and toenails are susceptible to the infection, which usually manifests as discoloration and thickening of the nail and crumbling edges. The condition most commonly occurs in toenails.

Between six and eight percent of the adult population suffers from nail fungus infection.

Who gets nail fungus infections?

Nail fungus infections are more common in men than women and in the elderly than the young. Additional traits or factors that raise one's risk of nail fungal infection include the following:

• Diminished blood circulation
• Slow growing nails
• A family history of fungal infection (genetics)
• Heavy perspiration
• Humid or moist work environment
• Wearing socks and shoes that prevent ventilation
• Walking barefoot in damp public places (swimming pools, gyms and shower rooms)
• Previous injury or infection to the skin or nail
• Diabetes, AIDS, circulation problems, a weakened immune system
• Tight footwear with crowding of toes
• Exercise that causes repeated minor trauma to the hyponychium (where the finger tip attaches to the nail)

What causes nail fungus infections?

Nail fungal infections are caused by microscopic organisms called fungi that do not require sunlight to survive. Most commonly, a group of fungi called dermatophytes (such as Candida) is responsible for nail fungal infections. However, some yeasts and molds also cause these infections.

Though Trichophyton rubrum is the most common dermatophyte that causes nail fungal infections, Trichophyton interdigitale, Epidermophyton floccosum, Trichophyton violaceum, Microsporum gypseum, Trichophyton tonsurans, and Trichophyton soudanense may also cause the infections. Common mold causes include Neoscytalidium, Scopulariopsis, and Aspergillus.

Pathogens that cause nail fungus infection usually enter the skin through tiny cuts or small separations between the nail and nail bed. The fungi grow when the nail provides a suitably warm and moist environment.

What are the symptoms of nail fungus infections?

Nails that are infected with fungus typically are thickened, brittle, crumbly, ragged, distorted, dull, and darker or yellowish in color. A patient may also experience onycholysis, where infected nails separate from the nail bed. Sometimes, nail fungal infections result in pain in the toes or fingertips, and they may even emit a slight foul odor.

Another symptom associated with nail fungus infections are fungus-free skin lesions called dermatophytids. These may be rashes or itchiness in an area of the body that is not infected with the fungus - much like an allergic reaction.

How are nail fungus infections diagnosed?

In order to diagnose nail fungus infections, a doctor will usually examine debris that is scraped from underneath the nail. The nail scrapings will be used in tests such as a potassium hydroxide (KOH) smear or a fungal culture. The KOH test can be quickly performed, while the fungal culture can take weeks.

Physicians must be careful when diagnosing fungal infections of the nail because several other conditions can result in similar symptoms. These include psoriasis, lichen planus, contact dermatitis, trauma, nail bed tumor, eczema, and yellow nail syndrome.

What nail fungus treatments are there?

Treating nail fungus infections can be a long and expensive process. There are oral antifungal medications, topical ointments, and alternative therapies. Over-the-counter creams and ointments are available, but they have not proved very effective.

Oral medications for nail fungus infection include Itraconazole (Sporanox), Fluconazole (Diflucan), and Terbinafine (Lamisil), which typically take up to four months before fully replacing the infected nail with uninfected nail.

Topical nail fungus treatments include antifungal lacquer or nail polish such as ciclopirox (Penlac) in addition to other creams. Use of topical remedies can clear nail fungal infections, but often does not completely cure the infection.

In some extreme cases, a physician will opt to remove the entire nail.

Alternative medicines used to treat nail fungal infections include Australian tea tree oil and grapefruit seed extract. However, there is no scientific evidence supporting the use of these products.

How can nail fungus infections be prevented?

Preventing nail fungus infections requires proper hand and foot hygiene. Some suggestions include:

• Keeping nails short, dry, and clean
• Wearing socks that breathe, usually synthetic
• Using antifungal sprays or powders
• Wearing rubber gloves to avoid overexposure to water
• Refraining from picking or biting nails
• Wearing shoes or sandals in public places and pools
• Ensuring that your manicure or pedicure salon properly sterilizes tools
• Stopping use of nail polish and artificial nails
• Washing hands after touching infected nails
• Avoiding sharing shoes and socks

Written by Peter Crosta M.A.


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