FAVUS

Synonyms: Tinea favosa; Porrigo favosa.

Favus is a contagious disease caused by a fungus, the achorion Schonleinii, which grows upon the skin in almost pure cultures and forms peculiar pin head to pea sized, cup shaped colonies called scutula, or sometimes larger, irregular, grayish yellow masses of dry, friable, mortar like material. The earliest lesion is a patch of hyperemia or superficial inflammation from which there may be a slight desquamation of thin gray scales. Then the colonies become visible as bright yellow specks at the mouths of hair follicles. During their development into typical, round, sharply margined, umbilicated crusts the hairs persist for a time and often one or two may be seen projecting from the center of a scutulum. Soon, however, all the hairs in an affected area become lusterless and slightly brittle; many break off, most of them fall out and the loss is usually permanent. When a crust that has been present for some time is removed, or falls off, it leaves a red, moist or slightly bleeding depression that later becomes the site of a thin white scar. New colonies arise between the old ones and the crusts extend and coalesce to form the mortar like accumulations, which have a pronounced odor that recalls the scent of mice or of stale, musty straw. After some time the older crusts disappear. When in an affected area most of the hair follicles have been destroyed and the skin converted into scar tissue, the disease may wear itself out, or it may extend to adjacent

areas until after years or decades a whole region, like the scalp, may have been involved. Lesions sometimes appear in more distant parts to which the spores have been conveyed probably through scratching. The disease affects the scalp usually, but occurs also upon the so-called non-hairy portions of the skin, over which it spreads sometimes with comparative rapidity, equaling in a few months a scalp involvement of many years. The lesions may cause slight pruritus. The disease is more common among males and starts usually before the fifteenth year. It is probably frequently contracted from domestic animals, for it occurs in cats, dogs, rabbits, fowls, horses and cattle and is common in mice and rats.

**DIAGNOSIS:** The scutula and mortar like masses are pathognomonic. In any doubtful case of favus a microscopic examination of scales or hairs from the affected region will reveal the presence of spores and mycelium. **TREATMENT:** All crusts should be removed with soap and water, and the hair cut short and epilated from day to day, until none is left in the affected region. An ointment consisting of a drachm of iodin in an ounce of goose grease is to be well rubbed in once a day. The remedy should be used for at least a month on nonhairy parts or for three months on the scalp. The treatment then may be discontinued for a time but is to be resumed at the first sign of recurrence. Years may be required to effect a cure upon the scalp.