Fungal infection of the nails, also known as onychomycosis, is a common problem among Americans. It is estimated that between 2% and 14% of the population has fungal nail infections, with the frequency of such infections increasing with age. Few children have fungal nail infections, while as many as 25% to 40% of people over the age of 60 do. Fungal infections of the fingernails are more common in men; fungal infections of the toenails are more common in women.
Nail fungus is becoming more common in the U.S. The rise in nail fungus is thought to be due to a combination of increased detection as well as increased risk of infection. Factors that contribute to this increased risk include aging of the population, spread of HIV/AIDS, tight footwear, vigorous physical activity, and use of communal swimming pools, locker rooms, etc.
Nail fungus is more than a cosmetic problem. It can be painful and interfere with daily activities such as walking, playing sports, writing, typing, and other activities that require manipulating small objects or repetitive finger use. An international study conducted by dermatologists found that nail fungus had a significant impact on the quality of life of people with the disease. The main problems identified were embarrassment, functional problems at work, reduction in social activities, fears of spreading the disease to others, and pain.
Nail fungus must be treated with medication once it occurs. Rarely, surgery may be necessary.
As the name implies, the disease is an infection of the nail caused by a fungus. Fungi are small, parasitic, plant-like organisms such as molds and yeasts. Two types of fungi commonly cause nail infections. The first type is called a dermatophyte, which means “plant that lives on the skin”. The second type, which occurs infrequently in the U.S., is a yeast. Many different yeasts may cause onychomycosis.
In temperate areas of the world, most nail infections are caused by dermatophytes. In the tropics, yeasts are the most common cause. In both cases, the fungi digest keratin, which is the major protein in nails, hair, and skin. The nails respond by overproducing keratin, which causes them to thicken and separate from the underlying skin.
The first sign of nail fungus is usually a small spreading white or yellow spot on the nail. Table 01 Because nail fungus rarely heals by itself, you should seek out medical treatment at the first sign of infection. Many people fail to seek treatment initially because the symptoms of nail fungus may appear to be nothing more than a blemish. If you suspect that you have a nail fungus, you should seek treatment because these infections can persist indefinitely when left alone. As importantly, treatment is likely to be more successful the earlier the infection is caught.
There are two common types of fungal nail infections. The first is infection of the nail bed under the nail. This type of nail fungus is the most common type of infection. The infection starts at the free edge of the nail plate and extends to the nail bed under the nail plate. It spreads from the tip or side of the nail and moves back. Typical symptoms include thickening or deformity of the nail, discoloration (green, yellow, brown, or black), and separation of the nail from the nail bed. In some cases, the skin around the nail may become itchy, red, or swollen. As the infection spreads, it becomes painful, and the pain may be severe. The nail may have a foul smell of decay.
The second common type of fungal nail infection affects the nail plate itself. In this type of nail fungus, the fungus directly attacks the nail plate rather than first infecting the tissue underneath. Initially, the nail looks white and crumbly in a speckled pattern, but eventually the spots may join to include the entire nail.
Table 1. Symptoms of Nail Fungus
Discoloration of the nail plate or bed Nail thickening or deformity Separation of the nail plate from the bed Inflammation of the surrounding skin Pain Foul smell
Nail fungus becomes more common with age. The apparent reason for this increased risk is that as people age, their nails begin to grow more slowly and start to thicken, making them more susceptible to attack by fungi.
Nails that are kept moist and warm have a higher risk of developing fungal infections. People who perspire heavily, work where their hands are frequently in water, wear tight socks or shoes that don’t provide ventilation, or who frequent locker rooms, swimming pools, or other public bathing facilities have a higher risk of developing fungal infections.
Nail and hair salons can spread fungal infections. Because the fungi that cause nail infections can be spread by contaminated instruments such as scissors, nail files, and razors, it is important to frequent only those nail and hair salons that have the highest standards of cleanliness and hygiene. Instruments should be properly sterilized between uses on different clients. Good hand washing habits are as important as in a doctor’s office.
Because the symptoms of nail fungus can mimic those of other diseases, your physician will first take a medical history. The questions will include questions to distinguish nail fungus from other conditions with similar symptoms, including psoriasis, contact dermatitis, nail bed tumors, and yellow nail syndrome (whose symptoms are caused by pulmonary disease).
Your doctor will perform a visual examination of the nails, followed by laboratory testing. After examining your nails, your physician should scrape some of the infected tissue from your nail for examination. He or she may observe the tissue under a microscope to look for fungi, or alternatively, your physician may try to grow the fungus in culture to identify it.
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