Dermatophytic infection of the feet also called ringworm infection of the feet, Tinea pedis, athlete’s foot or jungle rot is a contagious fungal infection of the skin of the feet. It affects either the space between toes or the soles. Together with fungal infections of the hands, they are believed to be the most common dermatophytoses. The involved species of fungi include Trichophyton rubrum, Trichophyton interdigitale and Epidermophyton floccosum and a combined infection can sometimes be seen.
Epidemiology frequently affects older children and young adults and is most commonly found in those aged twenty to fifty years. It is more commonly found in males than females. As all of the fungal skin infections, it is more frequently found in hot, humid climates. Predisposing factors include wearing tight footwear and having a condition called hypertrichosis (an abnormal amount of body hair). Because of widespread wearing of modern, tight shoes and world travelling, these infections have a very high incidence. They are also commonly acquired by walking bare-feet in pool and shower areas and can be transmitted between members of the same household. If fungi are present and infect another part of the body, it is possible for them to spread to the feet.
Tinea pedis symptoms
Redness, scaling, formation of large blisters and occasional peeling is seen. Often, a fungal infection of the toenails precedes it. If a bacterial infection follows it, the skin lesion is itchy, painful and emits a foul smell. There are four different clinical pictures associated with Tinea pedis (combination of them is possible):
- The interdigital type: is most commonly found between the forth and fifth toe and can spread to other parts of the feet. It can be dry and scaly or macerated (by definition softening by soaking in liquid). Excessive perspiration is commonly found. This is the most common form of all.
- The moccasin type: is most commonly located on heels, soles and the lateral borders of the feet. It can affect both feet. The skin is red, with small superficial elevations called papulae on the margin, finely scaly and hyperkeratotic (excessive thickening of the horny layer of the skin).
- The inflammatory/ bullous type: blisters filled with clear fluid are present on the sole, the instep. Pus indicates that bacteria have also infected the damaged skin.
- The ulcerative type: is observed when the interdigital infection has extended to the plantar or lateral part of the foot. Frequently, bacterial inflammation of the skin,the lymph nodi and fever are associated with this form.
Differential diagnosis: includes several different dermatological diseases like psoriasis, eczematous dermatitis, bullous impetigo, allergic contact dermatitis and dyshidrotic eczema.
Most of the times, diagnosing Tinea pedis is possible just by looking at the lesion. If the presentation is somehow misleading, the doctor may perform small scrapings of the affected skin and examine them under a microscope, use a special lamp called Wood’s lamp which makes some species of fungi glow (although species that cause athlete’s foot usually do not) or try to grow the pathogens in a special medium.
Tinea pedis is treated with anti fungal drugs which can be taken orally or applied topically (in form of a cream, powder, gel or spray). With the moccasin type, the topical medication has to be applied to the bottom and sides of the feet, with the interdigital type to the affected part plus the soles (because often the infection spreads). The moccasin type is based on the plantar surface of the feet where the skin is thick. Sometimes, urea based creams have to be applied together with topical anti fungals in order to soften it.
Patients with extensive hyperkeratotic or vesicular infections, those with accompanying infection of the nails, patients with diabetes, a compromised immune system (cancer, transplant patients) or disease of the peripheral vessels have to take oral anti fungal medications.
Because Tinea pedis can be quite itchy, scratching it can cause a bacterial infection of the already damaged skin. By touching the site of the inflammation, the pathogens can also spread to other parts of the body and cause the infection. The disease can extend to nails or cause a specific reaction called ‘id reaction’ where blisters can appear in distant parts of the body (by treating the feet it will usually go away).
Course and prognosis of the infection
This disease is commonly chronic in nature and repeats itself. If the patient has issues with veins in his legs, the pathogens can enter into more deeply lying tissues. Often, Tinea pedis will reoccur because patients do not stick to the prescribed therapy.
- use comfortable shoes that breathe
- keep feet dry
- change socks regularly
- wear sandals when walking in public pools or shower areas
- keep nails short and clean
- keep all bathroom surfaces clean and disinfected
- do not share shoes or towels with others.