ringworm, tinea

Dermatophytosis or ringworm is caused by Dermatophytes which are a type of fungi which affect skin, hair and nails. They are usually confined to superficial layers of skin (stratum corneum) and do not penetrate into deeper layers of skin.

Some dermatophytes are capable of producing toxins which can result in inflammation of skin.

Depending on the site of infection different names are given to the disease caused by dermatophytes. Different types of dermatophytes are involved. Itching is a common feature of ringworm infection.

Tinea capitis: This refers to infection of scalp. The usual causative organisms are Trichophyton tonsurans and Microsporum canis. The condition manifests as thickened brittle hairs which early break, redness of scalp and scaling.

Occasionally the hairs are broken as the surface of scalp and it appears as if the scalp is covered by black dots. Some patients develop small masses on the scalp. Occasionally small collections of pus may be seen.

Tinea corporis: The lesions are seen on the trunk or limbs. These appear as circular areas with slightly elevated borders associated wilh scaling. The usual causative organisms are Trichophyton mentagrophytes and Microsporum canis.

If the border of the lesion is scraped and the material thus collected dissolved in 20% potassium hydroxide and examined under microscope the fungus can be demonstrated.

Tinea cruris: The lesions are usually symmetrical with slightly elevated borders. Trichophyton rubrum, Trichophyton mentagrophytes and Epidermophyton floccosum are the usual causative agents.

Tinea pedis: This is infection of feet. It is also called as athlete’s foot. It is commonly seen in post pubertal age. It manifests as blisters and fissures between toes.

Tinea unguium: This refers to fungal infection of nails. The affected nail turns yellow in color and gets loosened from nail bed. The nail plate becomes thick and brittle.

Usual causative organisms are Trichophyton rubrum and Trichophyton mentaglophytes. Diagnosis can be confirmed by Potassium hydroxide preparation of scrapings and fungal culture. Usually one or two nails are affected.

Treatment of ringworm: For tinea corporis, cruris and pedis topical antifungal preparations are sufficient. Clotrimazole, Miconazole, Econazole, Terbinafine or haloprogin can be used. Any one applied twice daily for 3-4 weeks is effective.

For tinea capitis oral medication is required. Griseofulvin in a dose of 20 mg per kilogram of body weight per day in divided doses should be given for 6-8 weeks.

For tinea unguium local ciclopirox 8% has been used with some success. Many patients also need oral antifungal medicines. Itraconazole given orally for one week in a month and repeated for three months is quite effective.

Terbinafine given orally for 6 to 8 weeks is another effective drug. For toe nail infection it may have to be given for 12 weeks.

Tinea versicolor is a superficial fungal infection caused by Pityrosporum orbiculare which is also called as Malassezia furfur. This fungus causes small circular patches of altered pigmentation which are connected. Fine scaling is usually seen. The lesions may appear lighter or darker than surrounding normal skin.

The condition usually responds to local medicines. Clotrimazole or miconazole applied twice daily for about 2 weeks is usually effective. Other useful preparations are selenium sulfide or ketaconazole shampoo. Selenium sulfide can cause skin irritation.

Prevention of fungal infections: Fungi thrive in moist conditions. Hence skin should be kept dry as far as possible. It is better to avoid sharing clothes, shoes, combs, brushes and other personal items with other people.

Cotton clothing is better than synthetic clothing as cotton absorbs moisture well and helps to keep the skin dry. It is preferable to avoid very tight clothing. Any fungal infection in pet animals should be promptly treated as it can spread to humans.

SBI!

Fungal infections of skin Ringworm (dermatophytosis)