Favus

Favus is a parasitic disease of the skin caused by a minute vegetable fungus.

This disease may affect any portion of the body where there are hairs; but it prefers the scalp, especially the scalps of children. The fungus on which the disease depends is called Achorion Schonleinii, and falling on a congenial soil, gains access to the hair follicles, where it spreads and multiplies. In a short time it is perceived on the surface as a whitish speck, and later forms a very light-yellow umbilicated crust, the centre of which is perforated by a hair. A number of contiguous cups may coalesce, forming a crusty patch. The fungus, by its development and increase, presses on the follicular contents, and interferes with the nutrition of the hairs, and in time insures their destruction and permanent disappearance. Favus of the scalp usually makes its first appearance in childhood. Spontaneous cure rarely, if ever, occurs; and the affection lasts indefinitely, that is, as long as there is a hair follicle left for the achorion to lodge in. In this way the affection may be prolonged for twenty years or more. The most striking features of a long-standing case are the sparseness of the hairs over the affected area, the appearance presented being entirely different from that of any of the commoner forms of alopecia. The peculiar crusts may be present to aid the diagnosis, but not infrequently they are entirely absent from the surface, as various ointments, or even plenty of soap and water, are sufficient to prevent their development on the surface to an extent to prevent them to be visible to the naked eye.


The progress of the affection is extremely slow, and, when not checked by efficient treatment, may last for twenty years or more.

Favus on the body - that is, on the trunk or extremities - first exhibits its presence by a small erythematous patch like a commencing ringworm; this spreads until it has a diameter of an inch or more, when the characteristic crusts appear.