Onychomycosis

What is Onychomycosis?

Onychomycosis is a fungus that infects the nails. When this condition is caused by a type of fungi called dermatophytes, it’s known as tinea unguium. “Onychomycosis” is a broad term, including infections from multiple types of fungi like dermatophytes, yeasts, and another type known as saprophytic mold. Sometimes a nail might look abnormal but isn’t caused by a fungus. In this case, it’s called a dystrophic nail.

This infection can happen to both fingernails and toenails, but it’s much more common in toenails. The following sections dive deeper into various aspects of this topic, such as how common it is, different types, staging (which helps to determine the severity of the condition), how to diagnose it, and how to treat toenail onychomyocosis.

What Causes Onychomycosis?

Onychomycosis, also known as nail fungus, occurs usually due to a type of fungus called Trichophyton rubrum. However, other types of fungus, such as Trichophyton mentagrophytes and Epidermophyton floccosum, can also be the culprits. About 90% of toenail fungus and half of fingernail infections are due to these types of fungi.

A fungus called Candida albicans is responsible for about 2% of onychomycosis cases, particularly in the fingernails. There are other moulds not classified as dermatophytes that cause onychomycosis, which are usually found in toenail infections. These include moulds such as Fusarium, Aspergillus, Acremonium, Scytalidium, and Scopulariopsis brevicaulis, and they cause roughly 8% of nail infections.

Risk Factors and Frequency for Onychomycosis

Onychomycosis, a common infection often found in toenails, is seeing a rise in cases. In the past, a type of fungus called Trichophyton rubrum was thought to be just a contaminant in US labs. However, it’s now recognized as the main culprit behind most onychomycosis cases, especially with increased trips to Asia. Typically, at least half of the problems related to toenails are caused by various fungi. Estimates suggest that between 1% to 8% people have this infection, and this number is only growing.

Interestingly, people can actually inherit a higher chance of getting these infections from their parents. This risk is also increased by factors such as:

• Age
• Diabetes
• Tinea pedis (athlete’s foot)
• Psoriasis
• Weakened immune system
• Living with family members who have onychomycosis

Signs and Symptoms of Onychomycosis

When dealing with nail diseases, it’s crucial to take into consideration several factors including the length and effectiveness of any previous treatments. Understanding a patient’s history of medication is particularly important in suspected cases of onychomycosis (a fungal nail infection) to judge the compatibility of antifungal drugs with their current medications.

Other factors such as a history of hepatitis, whether the patient has travelled to areas where hepatitis is common, and their alcohol consumption should also be noted. Hobbies and pastimes can also play a role in disease recurrence or new infections. Certain conditions like Tinea manuum (hand fungus), cruris (jock itch), or psoriasis can often accompany onychomycosis. A thorough process including checks of the hands, feet, and scalp will provide a comprehensive overview of the patient’s condition.

Onychomycosis in the foot presents itself as thickened, discolored toenails. It’s normal for one or both big toenails to be affected. Alongside this, patients might have mild, dry tinea pedis (athlete’s foot) which they often mistake for dry skin.

Routine documentation, such as photos of the affected nail(s) and measuring the extent of the infection, are instrumental in estimating treatment duration and monitoring progress. The thickness of the infection on the nail(s) can provide an insight into how long it will take to manage the condition. To put this into perspective, toenails typically grow about one millimeter per month. Comparing this growth rate with the size of the infected area will allow us to predict treatment length. However, it’s important to remember that factors like age and poor blood circulation can slow down nail growth. Interestingly, fingernails also tend to grow faster than toenails.

Testing for Onychomycosis

To treat a nail infection effectively, it’s critical to identify how severe the infection is and what type it is. The type of nail fungus, also known as onychomycosis, can guide your doctor in deciding the best treatment for you.

The most common type of nail fungus is called distal lateral subungual onychomycosis (DSLO). This condition shows up as part of the nail lifting with an area of abnormal, thickened skin or a crumbling texture beneath the nail. Another less common type is white superficial onychomycosis (WSO), which appears as white, chalky spots on the nail’s surface. This is easily scraped off by a doctor using a small, curved instrument or a rotary file.

The least common type of nail fungus is proximal subungual onychomycosis (PSO), which develops over the nail’s growth area. PSO is usually seen in patients with conditions that weaken the immune system, such as acquired immunodeficiency syndrome (AIDS). The infection first affects the inside of the nail plate, but unusual thickening of the skin beneath the nail is not evident in this subtype.

The most severe stage is total dystrophic onychomycosis (TDO). This occurs after a very long time (10-15 years) of chronic infection with a certain type of fungus. It is characterized by significant thickening beneath the nail, nail plate destruction, and irregular nail bed surface. This stage not only presents the biggest challenge to treat but also has the highest risk of leading to skin ulcers beneath the nail, secondary bacterial infection, and serious tissue death in patients with poor blood flow to their extremities.

Tellingly, almost half of unusual-looking toenails are not due to a fungus. Hence, lab tests are vital to confirm the diagnosis, especially if the doctor considers treatment with medications that circulate in the bloodstream. Traditional lab tests using a solution called potassium hydroxide (KOH) on the skin or nail scrapings are 60% accurate but cannot identify the species of the fungus. However, if KOH is positive, it helps distinguish certain kinds of fungus. At present, the most accurate lab test (95%) is having a specialist examine a nail clipping under the microscope using two special stains.

Cultures or a test called PCR can help identify the exact cause of the infection. These tests are useful when the infection is atypical or when a type of fungus called a saprophyte, typically harmless, is suspected as the main cause of the disease. Two consecutive positive cultures of the same saprophyte are required before considering it as the primary cause and not just a contaminant. PCR can better detect certain types of fungus over cultures alone by about 20%.

A technique called dermoscopy can diagnose nail fungus in the clinic and can also readily differentiate nail fungus from nail changes due to repeated minor injuries. In the case of nail fungus, dermoscopy shows short spikes beneath the nail and lines running lengthwise on the nail, while lines running crosswise on the nail represent nail changes due to chronic minor injuries.

Treatment Options for Onychomycosis

Onychomycosis, also known as nail fungus, is best treated with antifungal medication taken by mouth. This type of treatment is especially important for severe cases or for patients with diabetes, as there’s a higher risk of ulcers developing under the nail. However, combining oral medication with other treatments like topical antifungals (applied directly on the nail), nail trimming or even chemical nail removal can lead to even better results. There are new topical treatments that work well for mild to moderate cases, particularly if the person would rather avoid taking pills.

Medications like terbinafine, itraconazole and fluconazole have been shown to clear 76%, 63% and 48% of fungal infections, respectively. In terms of topical treatments, efinaconazole stands out with a success rate of approximately 55%. Just so you know, ‘success’ here is determined by a completely clear nail and negative nail fungal tests, which is a high standard of measure. Sometimes even if the infection is gone, the nail might not look perfect due to scars from the infection.

Certainly, oral therapy is very effective, but may not be suitable for everyone due to its potential interactions with other medications. Plus, some people just prefer not to take medication by mouth. There are topical treatments available both over the counter and on prescription, with success rates reaching up to 18% for an efinaconazole solution, an antifungal nail polish. The choice of treatment will also depend on the severity of the infection.

If you’re due to start antifungal treatment by mouth, your doctor will review your medical history, especially if you have a history of alcohol use disorder and liver disease. They’ll perform some liver function tests before and during the treatment to ensure your liver is not adversely affected by the medication. Additionally, it’s very important to let your doctor know about all medications you’re taking, as some can interfere with your antifungal treatments, especially terbinafine. You may need to be monitored if you’re on other medications or have multiple health conditions. If there’s any risk for you, your doctor might recommend an alternative therapy or just nail trimming to control symptoms.

What else can Onychomycosis be?

If you’ve got a nail problem, it could be due to a number of issues. The following conditions can look very similar to a fungal nail infection, also known as onychomycosis:

• Yellow nail syndrome
• A reaction to certain drugs or medications
• Underactive thyroid (hypothyroidism)
• Nail cancer
• Nail psoriasis
• Skin irritation or allergies (contact dermatitis)

It’s really important to figure out the right cause, so that it can be treated correctly.

What to expect with Onychomycosis

The outcome of onychomycosis, a fungal infection that affects the nails, can vary depending on a number of factors:

• Type and severity of infection: The kind and degree of the fungal infection play a key role in determining the outcome. Infections that are confined to a small area or are just on the surface generally lead to better results.
• Immune system health: People whose immune systems are not functioning optimally, often due to conditions like diabetes and HIV, might see the disease stick around for longer periods of time.
• Response to treatment: The effectiveness of the treatment chosen can greatly affect the outcome. In some cases, oral and topical antifungal treatments can completely clear up the infection. However, the infection might not respond to traditional treatments in certain cases, causing it to persist or return.
• Compliance with treatment: Following the prescribed treatment plan faithfully is key for a positive outcome. If you don’t stick to the treatment plan, the infection could become chronic.
• Underlying health conditions: Certain medical conditions can impact blood flow to the nails, making treatments less effective. Conditions like poor circulation or peripheral vascular disease, a condition where blood vessels outside the heart are not working properly, can slow improvement.

Possible Complications When Diagnosed with Onychomycosis

While the infection isn’t life-threatening, it can still lead to several complications for patients. Here’s what might happen if the infection isn’t properly managed:

• Cellulitis: This is a skin infection that can lead to swollen and red areas on the skin.
• Sepsis: This is a dangerous condition where the body has a severe response to infection.
• Osteomyelitis: This is an infection in the bone that can cause severe pain.
• Tissue damage: The infection can cause harm to body tissues.
• Loss of nail: Persistent infection can lead to the loss of a nail.

Preventing Onychomycosis

It’s always a good idea for patients to wear appropriate shoes, keep themselves clean, and make sure to wash their hands and feet when using public bathrooms, swimming pools, or water parks. They should also avoid using damp towels. If there are any changes in the nails, it’s important to promptly visit a healthcare professional for diagnosis and treatment. Once treatment has started, patients should follow their medication instructions closely. If they don’t, it could affect the outcome of their condition.