Fungal infection of the skin may be superficial when it involves the skin and its appendages primarily or it may be deep mycosis with secondary manifestations on the skin. Fungal infections are more common in those with poor personal hygiene.
The superficial mycoses (called ringworm) are essentially caused by the dermatophytes- trichophyton, microsporon and epidermophyton. Most of the ringworm fungi are seen in the skin and they are transmitted from person to person by contact. These are anthropophilic fungi. Other ringworms fungi which cause human infection are found either in animals or soil. Fungal infections are diagnosed by their clinical pattern and demonstration of the fungus in skin scrapings and by isolation in culture.
Tinea Unguium (Onychomycosis)
The Different Fungal Infections Of The Skin
Tinea corporis: In hot humid climates, ringworm infections of the glabrous skin are much more common. The common organisms are Trichophyton rubrum and trichophyton mentagrophytes. Rarely, the fungus may spread to man from domestic pets. Ringworm infection of the groin is called Tinea cruris.
Classically, the lesions are circinate and this has lead to the term “ringworm”. The lesion starts as an erythematous itchy papule which enlarges to form a ring. The center is relatively normal and the borders are active, elevated and may be vesiculopapular. The lesion may enlarge up to 10cm. Neighbouring lesions may become confluent.
Tinea cruris:It is a common form of superficial mycosis. It is more common in males than in females. Obese subjects and diabetics are more susceptible. The lesion starts at the apex of the groin and extends to the inner aspects of the thighs, genitalia, perineum, gluteal regions or lower abdominal wall.
Once established, tinea cruris tends to be recurrent. The causative organism is most frequently Epidermophyton floccosum, but other fungi such as T. rubrum and T. mentagrophytes may also be responsible. T. mentagrophytes starts more acutely and the lesions may show inflammation. Tinea cruris has to be distinguished from erythrasma, seborrheic dermatitis, candidiasis, flexoral types of psoriasis.
Tinea Pedis (ringworm of the foot): Tinea pedis is more common in those who use footwear unhygienically. The incidence is higher in summer and monsoon than in winter. The fungus is spread through bath-mats, tubs and swimming pools. The condition is rare in children and adult females. The lesion may be intertrigenous, vesicular or dry squamous. The intertrigenous variety is seen in the warm and moist areas of the feet, the interdigital areas.
Tinea Unguium (Onychomycosis): This is fungus infection affecting the nails. The main organism are T.rubrum or T mentagrophytes, and only rarely Epidermophyton floccosum. The nails become opaque, brittle, and deformed with subungual hyperkeratosis. Tinea infection starts from the base of the free edge of the nail, mostly the lateral folds. Most fungal infections of the nail primarily affect the nail bed and the nail plate is affected only secondarily. The metric of the nail plate remains uninvolved. Several nails may be simultaneously affected or rarely all the nails of the fingers and toes may be involved. Only rarely is the condition bilaterally symmetrical. Fungal filaments can be demonstrated in the scrapings made from the subungual debris.
© 2014 Funom Theophilus Makam