Onychomycosis

Melinda J. Gooderham, MSc, MD, FRCPC

What is Onychomycosis?

Onychomycosis is a fungal infection that affects the nails of the fingers and toes. This condition can affect people of all ages, races, and sexes. Toenail infection is 25 times more common than fingernail infection and is commonly associated with athlete's foot (tinea pedis).

What Causes Onychomycosis?

Fungi, yeasts, and molds are the responsible agents for nail infection. By far, the most common culprit is a type of fungus called, Trichophyton rubrum. The fungi that give rise to onychomycosis can be the same ones that cause jock itch, ring worm, and barber's itch.

How Can Someone Get an Infection?

Onychomycosis is contagious. It is transmitted by direct contact or contact with contaminated materials such as shoes, socks, or walking barefoot over surfaces with a high density of fungal or yeast spores.

Although it is not a hereditary condition, not everyone is equally susceptible. There are families with genes that make them more prone to fungal nail infections. They are the ones who usually get onychomycosis at a younger age and those with repeated infections. Likewise, there are genes that have been shown to protect against acquiring the infection.

Immune dysfunction, particularly a defect in cell-mediated immunity also makes one more predisposed to onychomycosis. This group includes those on prolonged steroid therapy, those that are malnourished, or those with chronic illnesses such as diabetes.

Age and sex also play a role. Fungal nail infection is more common in males and one becomes more susceptible with increasing age. Children are less likely to have onychomycosis compared to adults and the incidence of onychomycosis may be as high as 60% in the elderly.

Lifestyle and certain activities may also be contributing factors. People who frequent public swimming pools, gyms, or locker rooms are more exposed to onychomycosis. Also people whose feet sweat or are frequently injured, are at increased risk of getting the infection.

What Does a Fungal Nail Infection Look Like?

Onychomycosis presents as nail abnormality or a progressive degeneration of the nail tissue (dystrophy). Nail changes may include: brittleness, change in shape, debris trapped under the nail, discolouration, thickening, and detachment of the nail. While nail dystrophy can be the result of many insults and conditions such as psoriasis, an estimated 50% or more cases are due to onychomycosis.

Onychomycosis can present in different patterns:

1. White superficial type presents as white flaky material on the surface of the nail
2. Distal/lateral subungual type presents as distally or laterally detached nail with a yellowish or brownish accumulated debris under the nail
3. Proximal subungual type presents as a white discolouration at the same area as the lunula (crescent-shaped whitish area of the nail bed), with colour more intense than the lunula.
4. Candidal onychomycosis (caused by yeast) presents with yellowish discolouration of the nail and detachment accompanied by swelling of the surrounding skin and loss of the cuticle.
5. Total dystrophic onychomycosis presents as a very thickened, opaque, and yellow-brown nail.

How is Onychomycosis Diagnosed?

Physicians can identify fungal nail infection by performing an examination most of the time. There are times when it becomes difficult to tell onychomycosis apart from other conditions that cause nail abnormalities such as psoriasis and trauma. A sample may be taken from the debris beneath the nail and examined microscopically or cultured for possible fungal growth. This laboratory procedure is important not only to confirm the diagnosis but also to identify the type of fungus and help determine the best treatment to be given.

What are the Treatment Options?

Treatment deserves special consideration as average cure rates remain low with relatively high relapse rates seen after successful treatment.

Over the counter and prescription anti-fungal creams do not typically work. Oral medications are generally required and sometimes they are combined with nail removal and/or application of nail lacquer. Presently available oral antifungal medications include: terbinafine, itraconazole, and fluconazole taken daily, in pulse or weekly, respectively. Topical nail lacquer, such as that containing ciclopirox olamine, can be effective and an important option for patients that cannot take oral medication.

X-ray, lasers, and photodynamic therapy have also shown promising results. The specialists associated with Probity Medical Research continue to participate in clinical trials to look for better options.

I am Afraid of the Side Effects of Taking Anti-fungal Pills. What Are They?

Oral anti-fungals may interact with other drugs, so it is important that your physician is informed of all the prescription and non-prescription medicines you are taking. Since oral anti-fungals are mostly metabolized in the liver, they can affect the liver but this is rare. Your physician may request certain blood tests to check your liver function to ensure that it is safe for you to take the pills.

What if I Decided Not to Have Any Form of Treatment?

Onychomycosis is not life threatening and many have lived with the condition for years; however, it can make someone more susceptible to secondary bacterial infection, particularly of the lower legs in those with poor circulation. Likewise, it may impose psychological stress because of the social stigma it carries and impact on daily life. Onychomycosis may also adversely affect ones occupation as it may affect the ability to perform certain tasks.

In a quality of life assessment of people affected by onychomycosis, the constant reoccurrence as well as the number of nails affected was shown to negatively affect quality of life. Moreover, 64 - 74% of those surveyed, admitted to embarrassment and lower self-image/self-esteem.

I have finished the course of my oral anti-fungal treatment and yet my nails don't look normal. Why is that?

Even in cases where treatment has been effective, the nails may have persistent abnormal appearance. The cells that produce the nail are mainly located behind the lunula (crescent-shaped whitish area of the nail bed). You have to wait for many months for the new, clear nails to reach the tip. The fingernails grow out at approximately 3mm/month and toe nails 1mm/month.

Will Onychomycosis Come Back After Treatment?

Unfortunately, there is a high recurrence rate even in patients considered to be successfully treated. Of the patients who showed negative results in microscopic tests and no fungal growth at the end of the treatment, 10 to 53% of them had recurrence over the next 36 months; however, some patients remain clear after one course of treatment.

What Measures Can I Take to Avoid Acquiring a Fungal Nail Infection?

• It is important that you keep your nails clean and trimmed. Refrain from removing the cuticle as this serves as a natural barrier from water and organisms getting inside the nail fold (skin around the nail).
• Keep your feet dry. Fungi grow easily in moist, warm environments. You may try using foot or anti-fungal powder and wear cotton socks.
• Avoid walking barefoot in places such as communal locker rooms or public swimming pools
• Be careful about where you get a manicure or pedicure; and make sure all tools and equipment are properly sterilized.
• Don't share personal belongings such as socks, slippers, or shoes especially with people known to have onychomycosis. Laundering socks does not totally eliminate fungal elements from the material.
• Make sure to seek treatment if you suspect other fungal infections anywhere on the body as this can be transmitted to the nails which are much more difficult to treat.

Dr. Melinda Gooderham is the Medical Director at the SKiN Centre for Dermatology in Peterborough, Ontario. The centre includes a state-of-the-art Phototherapy and Psoriasis Treatment Centre, Patch Test Clinic, Laser Clinic, and Dermatology Research Centre. To learn more about Dr. Gooderham's clinical research and ongoing studies visit: ResearchTrials.org - SKiN Centre for Dermatology

Where can I get more information?

Skin Care Guide: Fungal Guide

ResearchTrials.org: Toenail Fungus