Scalp ringworm

Tinea capitis is a clinical diagnosis more commonly known as scalp ringworm. It is one of the most common scalp infections that dermatologists encounter. Tinea capitis has been known about for several centuries but it has taken a long time for fungi to be recognized as the cause. Only for the last ninety years or so has an infectious agent been widely accepted as the cause of tinea capitis. With the development of microscopes came the realization that foreign bodies could be identified in the skin and hair of people with tinea capitis. Eventually these foreign bodies were identified as fungal colonies.

The word ringworm was a very popular term used to describe just about any type of skin condition where the affected areas were patchy and expanded over time. Scalp ringworm is still the common name for this infectious disease but tinea capitis has nothing to do with worms. Tinea capitis is caused by a wide range of fungi. Worldwide, Microsporum audouini is a very common cause, but increasingly Trichophyton tonsurans can also be found as a cause of tinea capitis, especially in Latin America. Other fungi that may cause tinea capitis include Trichophyton schoenleinii, Trichophyton megninii in Southern Europe and Africa, and Trichophyton violaceum in the Middle East. Microsporum gypseum can cause tinea capitis. This fungi is common in soil and may be transferred to humans by contact with infected animals.

Mechanism of scalp ringworm development

Fungal infectious agents are opportunists. The fungi like to enter the scalp skin through a cut or scrape. Once they get underneath the outer skin barrier they multiply and spread out in a circle much like ripples from a stone thrown into a pond. Fungi particularly like to locate themselves in and around growing hair follicles. The fungi get right into the hair fiber itself. This weakens the hair fiber and infected fibers can be very brittle and liable to break off. The condition can take many forms depending on the agent involved, the individual's immune response, and the type of hair they have. Some forms of tinea capitis may involve significant inflammation and possibly even scarring of the skin. Some infections may expand very rapidly to affect the entire scalp whereas others may progress very slowly and the individual may experience scaly skin and mild hair loss for several months or years before seeking the diagnosis from a dermatologist.

Typically, an infection spreads to cover a patch up to four centimeters in diameter but for some people the infection can be much larger. The patch may resolve in about 7 months from first infection but again some people can have tinea capitis for much longer. In general, tinea capitis involves flaking, scaling skin that may involve inflammation. The condition can look a lot like dandruff or seborrheic dermatitis. Along with the skin changes there can be some loss of hair. The infected hair is brittle and easy to break off. Affected individuals may have small patches of hair loss on their scalp and broken hairs may be observed. There are more severe presentations including the development of a kerion. This looks like a crusty, disgusting mass of dead skin. Still others have intense inflammation associated with the fungal infection.

Scalp ringworm detection

In the past, other disorders that involved patchy hair loss were often confused with tinea capitis. Even today, some dermatologists may confuse tinea capitis with alopecia areata. However, there are now techniques to test for the presence of fungi in scalp disease. The simplest method is to use a "Wood's lamp". This is a small lamp that emits ultraviolet light of a limited wavelength. When the light is shone on infected hair and skin, the fungi absorb the light and re-emit it as a fluorescent blue-green light. It can be quite difficult to find the fungi using this lamp so it can take a careful examination to find the fungi. There are some cases where the fungi involved does not show up as fluorescent under the Wood's lamp. Dermatologists will usually make a culture from hair or skin scrapings when they suspect tinea capitis infection whether or not the Wood's lamp test was positive or not.

Tinea capitis spreads quite easily. It may be spread from person to person through physical contact. However, the fungi in hair that breaks off or falls out can also spread infection. Hairs on brushes, hats, or chairs may spread tinea capitis. There can be cycles of expression with epidemics occurring from time to time. Outbreaks in schools are quite common where up to 50% of those children exposed to infected kids can catch tinea capitis.

Scalp ringworm treatment

Treatment varies depending on the infection looks like and what particular fungus is causing it. Some types of infections will resolve spontaneously and so no treatment may be given. Most commonly though an antibiotic called Griseofulvin is used. Griseofulvin is very effective against fungi in hair and skin but is not very good at treating yeast or bacterial infections. The Griseofulvin gradually accumulates in the skin and hair, it especially likes to bind with keratin which is a common component of hair and nails. The Griseofulvin blocks the fungus from infecting the keratin. It most likely stops the fungi from building new cell walls. The Griseofulvin is taken for several weeks. People usually have to return to the clinic at regular intervals to see if the infection has gone. Most people tolerate Griseofulvin very well. Side effects can include upset stomach, headaches, and fatigue.

More recently some fungi that cause tinea capitis have been showing some resistance to the drug Griseofulvin necessitating higher doses and longer courses of treatment. As an alternative to Griseofulvin, newer anti-fungal drugs like Terbinafine, Itraconazole, and Fluconazole are being prescribed. All have generally been shown to be effective in the treatment of tinea capitis and appear relatively well tolerated, with gastrointestinal symptoms being the most common adverse effect.

Scalp ringworm references

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