Anjali Sharma, Prof. Geeta Sumbali
Toe and fingernail infections caused by fungal organisms are known as onychomycosis. They are the most common nail diseases, which accounts for upto 50% of all the nail disorders. The symptoms may include white, yellow, blue or green discolouration, thickening, splitting and separation of the nail plate from the nail bed. Infection of the nails is generally caused by different species of dermatophytes like Trichophyton rubrum, T. interdigitale, T. violaceum, T. tonsurans, T. soudanense, Epidermophyton floccosum and Microsporum gypseum. Some of the saprophytic fungal species of Scytallidium, Scopulariopsis, Aspergillus, Fusarium and Curvularia and yeasts like Candida, Rhodotorula, Trichosporon and Geotrichum species may also be involved.
Fungi causing onychomycosis are keratinophiles, which have the ability to degrade the keratin of the nails, hair etc, by their enzymatic activity. Keratinophilic fungi, which cause disease of skin and hair in man and animals are commonly called as dermatophytes and their infections are known as cutaneous mycosis or dermatomycosis. Normally, these fungi live in the soil as self sufficient saprophytes but they are opportunists and may become parasitic by accident causing further infection by invading the fresh keratinized tissues.
Onychomycosis is a common condition affecting 10% of the general population and represents about 30% of cutaneous mycotic/fungal infections. Onychomycosis of fingernails may lead to pain, discomfort, and impaired/lost tactile functions. It has been observed that toenails are more commonly affected than fingernails. Toenail dystrophy can interfere with walking, exercise or proper shoe fit. Although it is rarely life threatening, its high incidence and prevalence makes it an important public health issue. Affected persons may experience an embarrassment in social and work situations, where they feel unclean and unwilling to show their hands and feet. As the infection progresses, the nails become brittle and break off in small pieces. If left untreated, the skin surrounding the nail tissue can become inflamed and painful. It is more common among the elders.
A number of factors may contribute to the rise of this disease e.g., age, poor peripheral circulation, type of occupation (farming, gardening, manual labour), athlete’s foot, diabetes mellitus, immuno-compromised patients (HIV), use of immunosuppressive therapy, cancer chemotherapies, use of antibiotics, longer exposure to pathogenic fungi, increased use of health clubs, commercial swimming pools, walking barefoot, wearing ill fitting shoes, nail biting (onychophagia), poor hygienic conditions, moist environment inside shoes, history of trauma (physical, chemical and mechanical), drug intake, contact with cosmetics and other associated illness. Diagnosis of onychomycosis is generally based on the appearance of symptoms and is confirmed by performing laboratory tests.
Nail infections in diabetic and HIV patients
Onychomycosis is more common in diabetic patients than in the non-diabetics. Diabetic patients suffering from decreased foot sensation are more prone to trauma, which damages the nail and nail matrix, opening portals of entry for the fungus to infect the nail. In such cases, the presence of fungal infection in the nails increases the risk of other infections of the foot and leg. Onychomycosis is also frequently observed in HIV patients as they are immuno-compromised. Prevalence of nail infections in HIV patients has been reported up to 12%. The increased susceptibility of HIV patients to fungal infections, especially, candidiosis, may increase their risk to more opportunistic fungal species. In HIV patients, the main etiological agent continues to be Trichophyton rubrum.
Nail infections in children
Children have a 30 fold decrease in the prevalence of onychomycosis as compared to adults possibly due to smaller contact surface, reduced environmental exposure, trauma and faster nail growth. However, some are more careless with respect to their cleanliness of hands and feet and acquire fungal infection during sports activity or through the contaminated environment. Children with Down’s syndrome and with immuno-deficiencies are likely to have more fungal nail infections caused by dermatophytes.
Nail infections in farmers and gardeners
Among farmers and gardeners, onychomycosis is very much prevalent chiefly because they are working with their fingernails and toenails continuously exposed to the soil, which is the largest reservoir of microorganisms. While working in the fields and gardens, they are also exposed to frequent nail trauma, which may increase the risk of fungal infections.
Management of nail infections
The management of onychomycosis is quite challenging since the infection is embedded within the nail and is difficult to treat. Therefore, the public should be educated about the toe and fingernail hygiene. Appropriate nail care should be explained and the importance of factors such as wearing loose shoes, keeping nails short and stopping a range of potentially risk behaviours like going barefoot in public places, wearing open sandals, wearing other people’s shoes and exposing feet and hands to damp environments should be stressed.
Oral antifungals used to treat onychomycosis include fluconazole, ketoconazole, itraconazole and allylamine terbinafine, which should be used only after doctor’s consultation. The treatment is often required for a minimum of three months and some patients may require prophylactic treatment to prevent recurrence. In addition to oral antifungals, there are some other antifungal ointments in the form of lotions/creams and medicated nail polishes that can be used to treat nail infections. Patients with onychomycosis often need to break old habits and learn new, healthier habits to achieve an optimal therapeutic response and prevent re-infection. There is a high rate of recurrence of onychomycosis, which ranges from 5-50%. Although most people remain well after the treatment, a few may get relapse of fungal infection, which may be due to either recurrence or re-infection. Recurrence is the return of disease within a year of therapy completion, whereas re-infection usually indicates predisposition of an individual towards acquiring an infection, which can be due to factors such as age, genetic factors, occupation, climate, nature and extent of initial infection or diabetes or immuno-suppression.
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