Definition:
Onychomycosis (also known as “dermatophytic onychomycosis,” “ringworm of the nail,” and “tinea unguium”) means fungal infection of the nail. It is the most common disease of the nails and constitutes about a half of all nail abnormalities.
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This condition may affect toenails or fingernails, but toenail infections are particularly common. The prevalence of onychomycosis is about 6-8% in the adult population.
Clasification:
There are four classic types of onychomycosis:
*Distal subungual onychomycosis is the most common form of tinea unguium, and is usually caused by Trichophyton rubrum, which invades the nail bed and the underside of the nail plate.
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*White superficial onychomycosis (WSO) is caused by fungal invasion of the superficial layers of the nail plate to form “white islands” on the plate. It accounts for only 10 percent of onychomycosis cases. In some cases, WSO is a misdiagnosis of “keratin granulations” which are not a fungus, but a reaction to nail polish that can cause the nails to have a chalky white appearance. A laboratory test should be performed to confirm.
*Proximal subungual onychomycosis is fungal penetration of the newly formed nail plate through the proximal nail fold. It is the least common form of tinea unguium in healthy people, but is found more commonly when the patient is immunocompromised.
*Candidal onychomycosis is Candida species invasion of the fingernails, usually occurring in persons who frequently immerse their hands in water. This normally requires the prior damage of the nail by infection or trauma.
Symptoms:
The nail plate can have a thickened, yellow-brown , or cloudy appearance. The nails can become rough and crumbly , or can separate from the nail bed. This thickening, discolouration and disfigurement are clearly visible.There is usually no pain or other bodily symptoms, unless the disease is severe.
Dermatophytids are fungus-free skin lesions that sometimes form as a result of a fungus infection in another part of the body. This could take the form of a rash or itch in an area of the body that is not infected with the fungus. Dermatophytids can be thought of as an allergic reaction to the fungus. People with onychomycosis may experience significant psychosocial problems due to the appearance of the nail. This is particularly increased when fingernails are affected.
The effects of onychomycosis aren’t simply cosmetic. A thickened nail may limit usual activities. It may press on the inside of footwear, for example, causing discomfort and pain. This in turn can cause problems when walking, and reduce mobility.
Causes:
Onychomycosis is caused by 3 main classes of organisms: dermatophytes (fungi that infect hair, skin, and nails and feed on nail tissue), yeasts, and nondermatophyte molds. All 3 classes cause the same symptoms, so the appearance of the infection does not reveal which class is responsible for the infection. Dermatophytes (including Epidermophyton, Microsporum, and Trichophyton species) are, by far, the most common causes of onychomycosis worldwide. Yeasts cause 8% of cases, and nondermatophyte molds cause 2% of onychomycosis cases.
•The dermatophyte Trichophyton rubrum is the most common fungus causing distal lateral subungual onychomycosis (DLSO) and proximal subungual onychomycosis (PSO).
•The dermatophyte Trichophyton mentagrophytes commonly causes white superficial onychomycosis (WSO), and more rarely, WSO can be caused by species of nondermatophyte molds.
•The yeast Candida albicans is the most common cause of chronic mucocutaneous candidiasis (disease of mucous membrane and regular skin) of the nail.
Risk Factors:
Risk factors for onychomycosis include family history, advancing age, poor health, trauma, living in a warm climate, participation in fitness activities, immunosuppression (can occur from HIV or certain drugs), bathing in communal showers (such as at a gym), and wearing shoes that cover the toes completely and don’t let in any airflow.
People with diabetes are at greater risk, as are those whose immune system is suppressed.
It’s possible to reduce your risk of onychomycosis by practising good nail care. This reduces the risk of other nail and foot-related problems, too.
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Diagnosis:
Onychomycosis (OM) can be identified by its appearance. However, other conditions and infections can cause problems in the nails that look like onychomycosis. OM must be confirmed by laboratory tests before beginning treatment, because treatment is long, expensive, and does have some risks.
•A sample of the nail can be examined under a microscope to detect fungi. See Anatomy of the Nail for information on the parts of the nail.
•The nails must be clipped and cleaned with an alcohol swab to remove bacteria and dirt.
•If the doctor suspects distal lateral subungual onychomycosis (DLSO), a sample (specimen) should be taken from the nail bed to be examined. The sample should be taken from a site closest to the cuticle, where the concentration of fungi is the greatest.
•If proximal subungual onychomycosis (PSO) is suspected, the sample is taken from the underlying nail bed close to the lunula.
•A piece of the nail surface is taken for examination if white superficial onychomycosis (WSO) is suspected.
•To detect candidal onychomycosis, the doctor should take a sample from the affected nail bed edges closest to the cuticle and sides of the nail.
•In the laboratory, the sample may be treated with a solution made from 20% potassium hydroxide (KOH) in dimethyl sulfoxide (DMSO) to rule out the presence of fungi. The specimen may also be treated with dyes (a process called staining) to make it easier to see the fungi through the microscope.
•If fungi are present in the infected nail, they can be seen through a microscope, but the exact type (species) cannot be determined by simply looking through a microscope. To identify what exactly is causing onychomycosis, a technique called culturing is used. Using a fungal culture to identify the particular fungus is important because regular therapy may not work on nondermatophyte molds.
…#The infected nail is scraped or clipped.
…#The scrapings or clippings are crushed and put into containers. Any fungus in the samples can grow in the laboratory in these special containers.
…#The species of fungus can be identified from the cultures grown in the lab.
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Treatment:
Medications
In the past, medicines used to treat onychomycosis (OM) were not very effective. OM is difficult to treat because nails grow slowly and receive very little blood supply. However, recent advances in treatment options, including oral (taken by mouth) and topical (applied on the skin or nail surface) medications, have been made. Newer oral medicines have revolutionized treatment of onychomycosis. However, the rate of recurrence is high, even with newer medicines. Treatment is expensive, has certain risks, and recurrence is possible.
•Topical antifungals are medicines applied to the skin and nail area that kill fungus.
…#These topical agents should only be used if less than half the nail is involved or if the person with onychomycosis cannot take the oral medicines. Medicines include amorolfine (approved for use outside the United States), ciclopirox olamine (Penlac, which is applied like nail polish), sodium pyrithione, bifonazole/urea (available outside the United States), propylene glycol-urea-lactic acid, imidazoles, such as ketoconazole (Nizoral Cream), and allylamines, such as terbinafine (Lamisil Cream).
…#Topical treatments are limited because they cannot penetrate the nail deeply enough, so they are generally unable to cure onychomycosis. Topical medicines may be useful as additional therapy in combination with oral medicines.
•Newer oral medicines are available. These antifungal medicines are more effective because they go through the body to penetrate the nail plate within days of starting therapy.
…#Newer oral antifungal drugs terbinafine (Lamisil Tablets) and itraconazole (Sporanox Capsules) have replaced older therapies, such as griseofulvin, in the treatment of onychomycosis. They offer shorter treatment periods (oral antifungal medications usually are administered over a 3-month period), higher cure rates, and fewer side effects. These medications are fairly safe, with few contraindications (conditions that make taking the medicine inadvisable), but they should not be taken by patients with liver disease or heart failure. Before prescribing one of these medications, doctors often order a blood test to make sure the liver is functioning properly. Common side effects include nausea and stomach pain.
…#Fluconazole (Diflucan) is not approved by the Food and Drug Administration (FDA) for treatment of onychomycosis, but it may be an alternative to itraconazole and terbinafine.
•To decrease the side effects and duration of oral therapy, topical and surgical treatments may be combined with oral antifungal management.
Surgery
Surgical approaches to onychomycosis treatment include surgically or chemically removing the nail (nail avulsion or matrixectomy).
•Removing the nail plate (fingernail or toenail) is not effective treatment on its own. This procedure should be considered an adjunctive (additional) treatment combined with oral therapy.
•A combination of oral, topical, and surgical therapy can increase the effectiveness of treatment and reduce the cost of ongoing treatments.
Research:
Most drug development activities are focused on the discovery of new antifungals and novel delivery methods to promote access of existing antifungal drugs into the infected nail plate. Active clinical trials investigating onychomycosis:
Phase III
*A topical treatment, AN2690, is being developed by Anacor Pharmaceuticals. It is active against Trichophyton species.
*A medicinal nail lacquer, MycoVa from Apricus Biosciences,[40] contains terbinafine as the active ingredient and a permeation enhancer DDAIP which facilitates the delivery of the drug into the nail bed where the fungus resides.
*A comparison of delivery methods for itraconzole
*Safety and tolerability of topical terbinafine
*Laser-based treatments
*Topical IDP-108
*Bifonazole cream application after nail ablation with urea paste
Phase II
*Posaconazole, taken orally.
*A topical treatment, NB-002, is being developed by NanoBio Corporation. It has completed Phase II trials
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose
Resources:
http://en.wikipedia.org/wiki/Onychomycosis
http://www.emedicinehealth.com/onychomycosis/page7_em.htm
http://www.bbc.co.uk/health/physical_health/conditions/onychomycosis1.shtml
http://www.aafp.org/afp/2001/0215/p663.html
