Definition. A contagious vegetable parasitic affection, characterized by pin- head-to pea-sized friable, cup-shaped, dry yellow crusts.
Symptoms. The common location of this disease is on the scalp but it may occur elsewhere, even in rare instances on the mucous surfaces. It begins as a circumscribed or diffused inflammation with scaling, followed by the formation of yellowish, pin-head-sized crusts seated about the hair-follicles. While concave from the first, as the crusts increase to the size of a split pea they appear more cup-shaped, especially in isolated lesions. Thus a typical cup is split-pea in size, round, umbilicated, perforated by a hair, and sulphur- colored. The crusts are always friable and can be readily powdered between the fingers. If they become aggregated into masses the round shape may be only evident at the free border. When the crusts are removed the surface beneath is found irregular depressed, moist, reddened, shining, cup-shaped and atrophic. this suppurating excavation naturally leads to scarring. As a consequence, after a period of several months, hairless, white atrophic spots may be seen. The hair is often affected, becoming dry, brittle, lusterless, may split, break off, fall out or be easily drawn out.
The nails are occasionally attacked, usually by scratching the scalp. There may be evident through the smooth outer surface of the nail distinct sulphur-yellow spots, or the nail may become dry, opaque, split, furrowed, fissured and raised from its bed as is seen in other parasitic diseases of the nails.
The non-hairy parts, if invaded, may show typical lesions with the same vigor and persistence as those on the scalp, but usually atypical forms occur resembling ringworm. These develop as round scaly patches, become clear in the center and form a vesicular, papular, scaly or smooth elevated ring. The juncture of two or more patches will form figurate or gyrate lesions containing possibly some characteristic favus crusts.
The course of favus is extremely chronic, often lasting for years, in some instances a lifetime, but fortunately it is feebly contagious as compared with ringworm. Varied sensations of itching, tenseness and fullness may be present but are often due to such complications as pediculosis, impetigo, eczema or cellulitis. The characteristic odor of favus has been likened to musty straw or mice.
Etiology and Pathology. Filth and personal uncleanliness are essential predisposing factors and, although the disease is directly contagious from person to person and from animal to animal, or from the latter to man, it is rarely communicated to a well-cared-for skin. The disease usually begins in childhood and once established multiplies with greater luxuriance than any other vegetable parasite. The sole cause is a vegetable organism known as the achorion Schonleinii. This fungus consists of mycelium and spores and may be found in the hair, hairfollicles and crusts. Secondary changes of an inflammatory nature occur in the corium.
For microscopic examination a hair may be extracted, soaked in a 5 per cent. solution of caustic potash and then slightly flattened out on a glass slide or a particle of favus crust may be prepared for examination by first macerating it in a solution of ammonia, which isolates the parasitic fungi. The spores are about 1-3000th of an inch, and the mycelium filament smaller in diameter. A magnifying power of 300 to 500 brings them in plain view. They may be stained a brownish color by moistening them with a few drops of an aqueous idoin solution to which has been added potassium iodid.
Diagnosis. Eczema occurs in diffuse ill-defined patches. Its crusts are yellow, brown or darker, tenacious, not powdery, without a characteristic odor, and while the hair of the affected parts may be matted together, it is not destroyed. There is practically no scarring. Psoriasis presents whitish scales covering a smooth red surface, which readily bleeds. The hair is unaffected and there is no odor or scarring. Dermatitis seborrhoica is usually diffused on the scalp while sharply defined on the surface. Its scales are fatty and the skin beneath is usually smooth and pale is color. Any resulting loss of hair is only a general thinning and often temporary, while scarring never occurs. Ringworm shows uniform scaliness of the patch, a vesicular advancing border, and stubbly hairs. The microscope will differentiate the two forms of fungus and may be used to assist in the diagnosis of favus from any resembling disease.
Prognosis. Favus of the body responds readily to treatment. When the scalp and nails are involved a persistent effort alone will yield good results, for the conditions are very rebellious. The general health is commonly unaffected.
Treatment. When the scalp in involved, long and tedious treatment is apt to ensue and the microscope should repeatedly be used to demonstrate the degree of cure. Treatment should be persisted in beyond any evident necessity. The hair should be cut short and the crusts softened with applications of oil for a few hours and he head covered with a cap or hood. Then a lather of green soap and hot water applied for a thorough cleansing. There is a choice of local antiparasitic measures: such as saturated solutions of sulphurous acid or sodium hyposulphite; 1 to 4 per cent. solution of formalin; a sulphur ointment, 2 drams to the ounce of lard or lanolin; and in obstinate cases, oleate of copper ointment, 1 to 3 drams to the ounce; betanaphthol, 1 part to 8 of ointment base; resorcin, 1 part to 3 of lanolin and 5 of sweet almond oil; and mercuric chlorid, 2 grains to the ounce of ether, alcohol or water. Epilation of the diseased hairs is usually essential and should be employed before the above- mentioned local treatment. Hairs may be removed with epilation forceps or by grasping the hairs between the thumb and a blunt-tongued spatula, or with compound pitch sticks which are heated, tangled in the hairs of the diseased area and, when cool, quickly withdrawn, bringing the hairs with them. Bulkley’s formula for this purpose is as follows:
R Carae flavae, 3iij; 12
Laccae in tabulis, 3iv; 15
Resubaem 3vi; 24
Picis Burgundicae, 3xxi; 44
Gummi dammar, 3jss; 45 M.
When it is possible to use the X-rays it should be the first choice for treatment of obstinate favus. The technic is the same as employed for ringworm and as in that disease, the massive dose method is preferable.
Favus of the body is readily cured, after the removal of the crusts, by a mercurial, betanaphthol or sulphur ointment.
Favus of the nails is obstinate. The affected spots should be repeatedly scraped and pared thin and a strong antiparasitic ointment rubbed in twice daily. A mercurial, betanaphthol or resorcin plaster may be worn either continuously or only at night. Avulsion is seldom necessary, although the quickest method of cure. I always use the X-rays to the point of dermatitis in the treatment of nail favus.
Adjuvant medication may call for Kali carb., Lycopodium, Mez., Nat.mur., Phosphorus, Staphysagria, and Sulphur.