It is an uncommon scalp problem and not usually serious in terms of being debilitating or life-threatening but a lesser known infection can lead to extensive damage of the scalp. It may result in hair loss and scarring of the scalp which can be irreversible. The cosmetic effects may have a host of psychosocial implications. This condition is known as favus.
What is favus?
Favus is a type of superficial fungal infection that mainly affects the scalp. It is considered to be a severe form of scalp ringworm that is medically termed as tinea capitis. Favus is also known as tinea favosa and is mainly caused by a species of skin fungus known as Trichophyton schoenleinii. Other fungi may sometimes also be responsible. Although the scalp is most commonly affected, it can also involve the beard, nails and body in rare cases.
This infection may affect males and females equally. It can occur in adults and children. Although flavus may occur globally, it is rarely seen in the United States and often associated with poverty and malnutrition. The infection tends to persist for years, even decades, resulting in hair loss and scarring on the scalp in the more severe stages. While oral medication can be curative and eradicate the infection, complications like scarring alopecia cannot be reversed.
Causes of Favus
Favus is predominantly caused by the dermatophyte Trichophyton schoenleinii. Less commonly other fungal species may be responsible including Trichophyton violaceum, Trichophyton mentagrophytes var quinckeanum, Microsporum gypseum, Microsporum gallinae and Microsporum canis. Although rare, the fungi can be contracted from animals and even inanimate objects.
Dermatophytes are a group of fungi that have a predilection for skin. These fungi contain enzymes that can digest the skin protein keratin. It causes superficial infections and the areas that are more commonly infected by dermatophytes includes the feet (tinea pedis or athlete’s foot), the groin region (tinea cruris or jock itch) and the scalp (tinea capitis or scalp ringworm).
These fungi tend to thrive in warm, moist and dark areas of the body. It can be easily spread from one area of the body to another especially when scratching these areas. Most dermatophyte infections are highly contagious meaning that it can easily be transmitted from one person to another. Direct skin-to-skin contact or even indirect contact via shared objects can spread the fungus. It is more likely to occur when there is a preceding injury to the skin.
In the case of favus, it does not appear to be highly contagious even among those that live in close quarters like family members. The condition is mainly seen in areas where poverty and malnutrition are present. Sub-standard living conditions and neglect are some of the other risk factors. It is important to note that it can also occur in developed nations within areas where these conditions are present.
Signs and Symptoms
The most common location of the infection in flavus is the scalp. However, it can occur in the nails (nail fungus or onychomycosis), beard (tinea barbae) or on the body (tinea corporis). Even when the infection occurs in these other areas, it usually begins on the scalp. The condition typically presents with yellow crusts similar resembling a honeycomb. It is sometimes mistaken for seborrheic dermatitis. Hair loss and scarring occurs in later stages.
The presentation of favus appears in three distinct stages:
- Stage 1: The hair is unaffected but the area around the hair follicles are red and inflamed (erythema).
- Stage 2: Yellow crusts (scutula) form around the hair and clump together with some degree of hair loss.
- Stage 3: Extensive involvement of the scalp (at least one-third of the scalp) with widespread hair loss and scarring.
Sometimes favus presents atypically and can mimic dandruff, seborrheic dermatitis, psoriasis and impetigo. It is important to note that secondary bacterial infections such as impetigo can occur as a complication of favus.
Diagnosis of Favus
The diagnosis of favus usually requires further investigation beyond Wood lamp examination. This involves microscopic examination of skin scrapings in a potassium hydroxide (KOH) solution. A culture is also done where the fungi from the scrapings are grown in a laboratory to positively confirm the causative organism.
Treatment of Favus
Favus does not resolve spontaneously. This means it will not ease or clear without medical treatment. Conservative measures like hair removal and washing regularly with non-medicated shampoos will not treat the conditions. The treatment for favus involves both topical and oral medication similar to that used for treating tinea capitis.
Treatment is usually continued for longer than it is for tinea capitis. While medication can eradicate the infection, the complications such as hair loss and scarring may be irreversible in more severe cases of favus. Where present, secondary bacterial infections may first be treated before the fungus.
Lotions, creams, ointments and shampoos containing ketaconazole and selenium sulfide. However, this may be only effective on its own in milder cases where the hair is not involved. Most of the time oral medication is necessary.
Drugs used in the treatment of favus includes griseofulvin but is not available in all countries. Other drugs like fluconazole, itraconazole and terbinafine can also be effective.
Prevention of Favus
Although favus is not highly contagious like other dermatophyte fungal infections, close contacts like family members who have the infection should also be treated simultaneously to prevent recurrence. Preceding skin problems that may increase the risk of a fungal infection should also be treated to prevent favus from arising.
The general preventative measures for tinea capitis can also be applied to favus. This includes not sharing personal items such as combs and washing the head regularly. However, the effectiveness of these measures in favus may be limited since the condition is known not to be highly contagious.
The focus of prevention should be on the known risk factors of favors. Addressing malnutrition and poverty should be the main considerations in preventing favus. Since favus is not common and not life-threatening, the prevention of this infection is usually not of concern to health authorities.