- Causes of Toenail Fungus
- Risk Factors in Acquiring Fungus
- History of diabetes
- Presentation and Clinical Manifestation of Toenail Fungus
- Classification of Fungal Infection of the Toenails
- 1. Distal Subungual Onychomycosis
- 2. Proximal Subungual Onychomycosis
- 3. White Superficial Onychomycosis
- 4. Candidal Onychomycosis
- Diagnosing Toenail Fungus
- Treatment Modalities in Managing Toenail Fungal Infection
- Medical Modalities
- Laser toenail fungus Removal
- What to Observe During Treatment
- Supportive Treatment for Toenail Fungus
- Prevention and Home Remedies
Otherwise called Onychomycosis, nail ringworm and tinea unguium, toenail fungus corresponds to fungal infection of the toenail.
It is one of the most prevalent nail diseases, with 20% of the population worldwide being affected. [1, 2, 3, 4]
Picture 1 : Fungal infection of the toes
Image Source: www.fungusfacts.com
Causes of Toenail Fungus
The more common etiologic agents of toenail fungus include Candida, dermatophytes and nondermatophytic molds. Common dermatophytes include Trichophyton rubrum, Epidermophyton floccosum, Microsporum gyrseum and Trichophyton interdigitale.
Non-dermatophytic molds, meanwhile, are best exemplified by the species of the genera Scytalidium, ASpergillus and Scopalaropsis. 
In the tropical regions of the globe, wherein hot and humid climates are present, Candida and nondermatophytic molds prevail. In temperate countries of the Western part of the world, dermatophytic species, on the other hand, are the more prevalent species. [1, 5]
Risk Factors in Acquiring Fungus
Conditions increasing one’s risk of acquiring fungal diseases of the toenail include: [1, 6, 7, 8]
- Male gender
- Older age – larger exposure to fungi, slow growth and thickening of nails and decreased blood circulation can lead to fungal infection of the toenails
- Positive family history of infection
- Humid, moist environment
- Heavy sweating or perspiration
- History of psoriasis
- Frequent usage of tight-fitting shoes and socks, preventing feet ventilation and not absorbing perspiration
- Being barefoot and not using any footwear in damp areas like swimming pools, shower rooms, locker rooms and gymnasiums
- With tinea pedis infection, more commonly termed as athlete’s foot
- Presence of minor nail or skin injury
History of diabetes
- With vascular insufficiency or problems in circulation
- Immunocompromised states
- Not drying of feet thoroughly after bathing and exercise
- Use of artificial or cosmetic nails
Presentation and Clinical Manifestation of Toenail Fungus
- After fungi penetrate the nail by entering an area of nail trauma, they then grow and multiply. Eventually, these then spread in areas of warmth and moisture, particularly inhabiting the feet inside the socks and shoes. 
- Thereafter, symptoms of fungal infection ensue. Nails thicken and changes their color into either yellow, white, black, or even green. They become brittle and if severe, can be broken off and completely detach from the toes. The skin surrounding the nail can present with inflammation and be tender and painful to touch. White and yellow patches may appear on the nailbed itself or along with the scale-like lesions on the nearby skin. 
Picture 2 : Fungi can also cause toenails to be broken off and detached.
Photo Source: www.toenailfunguscured.com
Picture 3: Toenail Fungus
image source : blogspot.com
Unless the disease is untreated and have been complicated, no pain, tenderness no any other symptoms may be observed. 
Classification of Fungal Infection of the Toenails
Four classic types of onychomycosis, or toenail fungus, are known to exist: 
1. Distal Subungual Onychomycosis
- Brought about by Trichophyton rubrum, this is the most common form of toenail fungus. This is usually seen affecting the nailbed and the area beneath the nail plate.
2. Proximal Subungual Onychomycosis
- This is the least common form of tinea unguium. Mostly found among immunocompromised patients, this condition is characterized by fungal invasion of a nail plate by means of the proximal nail fold.
3. White Superficial Onychomycosis
- Accounting for the 10% of cases of toenail fungus, this is characterized by the presence of white islands. These so-called islands are formed from the invasion of the superficial fungus of the nail plate.
4. Candidal Onychomycosis
- Candidal infection of nails require prior trauma or nail damage of the nail. These species penetrate those nails frequently met and immersed in water.
Diagnosing Toenail Fungus
- A thorough history and physical examination would sometimes be enough to diagnose fungal infections of the toenails. However, since other nail conditions can mimic this type of infection, diagnostic examinations may also be done for confirmation.
- In confirming the diagnosis, a physician usually acquires some of the patient’s nail clippings to run some tests. Usual methods include the use of culture, histology and potassium hydroxide (KOH) smear. The most sensitive of which being the direct smear combined with histological examination, and biopsy of the nail plates using the acid-Schiff staining. [11, 12]
Treatment Modalities in Managing Toenail Fungal Infection
It is useful to note that complete eradication of symptoms of toenail fungus is slow. This may last for a year or even longer, for new growth of nail must fully replace the previously infected one. 
- Fungal infection of the toes may be medically managed. This is done through the use of medication, both oral and topical.
- Oral medications are indicated as the fungi reaches the circulation. Two of the most commonly prescribed oral antifungal drugs are Itraconazole and Terbinafine. Consumption of these oral medicines for several weeks may result to successful elimination of the fungal etiologic agent. However, these drugs come with a number of side effects: loose bowel movement, nausea, pruritus, headache and inability to taste.
- Topical antifungals, on the other hand, correspond to nail paints or lacquers. These are not as effective as oral medications since it is superficially applied and it has to be adequately absorbed to reach the infection. They are applied for a span of 12 months for sufficient results. 
Laser toenail fungus Removal
- The US FDA has already approved laser therapy for the treatment of toenail fungus. On one clinical trial, it was found that after 9 months of laser treatment, 33% of the subjects had complete eradication of toenail fungus. A disadvantage, however, is the cost. This is aside from the usual side effect of burns. 
Image 3 : Laser therapy can be done in managing toenail fungus.
What to Observe During Treatment
- Once treatment is working and taking effect, new healthy nails should be visibly growing from the base of the nailbed. The old infected nail should then be clipped off as it grows out. The non-infected fresh nail shall grow continuously in a forward direction. As it reaches the edge of the toe, the nail shall visually be normal again. [8, 14]
Supportive Treatment for Toenail Fungus
Aside from medication, the following should be abided and adhered on to for appropriate treatment: 
- Cut toenails short; file nail thickening.
- Avoid nail irritants and injury.
- Keep feet dry and cool.
- Use a different pair of scissors and nail equipments for nail care of normal uninfected nails.
- Avoid wearing ill-fitted tight shoes; instead wear wide, open toed ones.
Prevention and Home Remedies
Since the toenail fungus takes quite a long time to treat, prevention is a main goal for management. To prevent toenail fungal infection, one must: [7, 8]
- Wear protective shoes or sandals in public pools, shower and locker areas, and gyms.
- Do not wear someone else’s shoes or socks.
- Wash the feet regularly and dry them meticulously.
- Keep toenails trimmed.
- Always disinfect tools for nail care before use.
- Wear well-fitting shoes; avoid narrow toed footwear and those with high heels.
- Consider replacing old footwear, which could already be contaminated with fungi.
- Onychomycosis. Dorland’s Medical Dictionary
- Rapini, R, et al. Dermatology (2007). Mosby. St. Louis. p. 1135
- Chi, C, et al. The Causative Pathogens of Onyshomycosis in Southern Taiwan. Mycosis. 48(6): 413-20.
- James, W, et al. Andrew’s Disease of the Skin. Clinical Dermatology. Saunders, Elsevier. 2006.
- Karimzadegan-Nia, M, et al. Comparison of Direct Smear, Culture and Histology for the Diagnosis of Onychomycosis. Australian Journal of Dermatology.2007; 48 (1): 18-21.
- Weinberg, JM, et al. A Comparison of Diagnostic Methods in Evaluation of Onychomycosis. Journal of American Academy of Dermatology. 2003; 49(2): 193-7.