Ringworm – a fungus, not a worm!

by Media Xpose

By Dr Kesiree Naidoo

Ringworm is the common name for a type of fungal infection caused by a group of fungal organisms called dermatophytes. The proper name for ringworm is dermatophytosis or tinea.  Ringworm (or tinea) is not caused by worms as the name suggests, but is named for the typical appearance of a rash that is ring-shaped.

Dermatophytes can cause infection of the skin, hair and nails. They are easily spread from person-to-person contact, contact with pets and from the environment. Dermatophytes are very resistant and contagious.

There are many different types of dermatophytes, but the most common cause of infection in humans is trichophyton rubrum and trichophyton tonsurans.

Tinea infection is named for the area of the body it affects. It is typically very itchy and can be passed on by sharing towels, clothing, or socks and shoes from a person that has the infection. Walking barefoot on wet floors and outside in soil is another way of getting the infection on your feet. Tinea thrives in hot humid environments which is why common areas that are affected are the groin and between the toes.

Tinea corporis (of the skin on the trunk)

Dermatophyte infection of the skin on the trunk is called tinea corporis. It typically appears as a circular or annular ring on the skin with an outwardly spreading scaly, red edge and an area of central clearing.  The ‘active’ edge often has tiny visible pustules. Tinea corporis can be an isolated patch or multiple coalescing patches and can occur at any age.

Tinea corporis can be treated with a topical antifungal for minimal infection, but more widespread disease needs oral medication. While it is easily diagnosed by a doctor or dermatologist, it can sometimes appear atypical and be confused with eczema. Patients with eczema often get secondary infection with fungus which makes it more difficult to differentiate the eczema from the fungal infection.

Another very common fungal infection on the trunk is pityriasis versicolor caused by Malassezia yeasts. It is not usually itchy or inflamed, but presents as flat hyper pigmented or hypo pigmented, lightly scaling patches on the trunk which are frequently recurrent in hot, humid weather.

Tinea facei (of the face)

Dermatophyte infection of the face is called tinea facei and typically occurs in children from close contact with pets. This type of fungal infection is often mistaken for eczema and treated with topical steroids, which then distorts the clinical picture so the doctor is no longer able to see the typical pattern and the active edge with pustules to identify a fungal infection.

When eczema on the face seems resistant to treatment it may be that there is a secondary fungal infection and a skin scrape with examination of the cells under a microscope can help to make the diagnosis.

Tinea cruris (of the groin)

Dermatophyte infection of the groin is called tinea cruris or ‘jock itch’. It occurs mostly in men and boys and is associated with sweating in the groin area and tight clothing, creating a humid environment. The typical well-defined edge may spread out onto the upper thighs. Yeast infections caused by candida can also cause an itchy rash in the groin. Candida infection typically presents with a white skin discoloration.

Tinea capitis (of the scalp)

Dermatophyte infection of the scalp is called tinea capitis. Tinea capitis generally affects children before puberty. It can appear on the scalp as a patch of hair loss, scaling white or grey patches, yellow pustules or black dots. It may also be a red and inflamed patch and sometimes even a large pus-filled boil called a kerion.

It can be spread by close contact with pets and by sharing hairbrushes, bedding and towels. Tinea capitis may be mistaken for eczema, but eczema does not cause hair loss. Tinea capitis is uncommon in adults, usually only affecting those that are immunocompromised.

Scalp fungal infections always need oral medication for at least 6 to 8 weeks. The hair usually grows back once the fungus is treated.

Tinea pedis (of the feed)

Dermatophyte infection of the feet in called tinea pedis, commonly known as ‘athletes’ foot’.  This type of fungal infection is common in sportsmen or any occupation that needs to spend a prolonged time in closed footwear, like safety boots.

Tinea pedis occurs more in older children and most often occurs in the toe web spaces. It may also present as tiny itchy blisters on the feet or a thickening and scaling of the entire foot, also called ‘moccasin type’ tinea pedis, which can only be treated with oral medication.

It typically affects just one foot, or two feet and one hand. This asymmetry in presentation points to ‘moccasin type’ tinea pedis and not just dry skin.  The subtype of athlete’s foot that occurs between the toes may be treated by easily available over-the-counter creams, though recurrence is the norm.

Tinea unguium (of the nails)

Dermatophyte infection of the nails is called tinea unguium or onychomycosis. This most often affects the big toe nails with subsequent spread to the adjacent toenails. An injury to a toenail can predispose you to nail fungal infection. This is the most difficult type of fungal infection to treat.

Oral treatment is most often needed and the maximum success rate with all treatments available is 60-70 %.

Some patients with very minimal nail involvement, which we call distal lateral onychomycosis, can be treated with topical prescription nail treatment. Treatment is always for prolonged periods and success is not guaranteed.

Fungal infections are sometimes difficult to differentiate from other skin rashes like eczema, but once a diagnosis is made most fungal infections can be treated successfully. Parents and caregivers should make careful observations as rashes develop and seek advice early from your paediatrician or dermatologist.

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