Favus
Encyclopedia
Favus is a disease
usually affecting the scalp
, but occurring occasionally on any part of the skin, and even at times on mucous membrane
s.
) grouped in patches like a piece of honeycomb, each about the size of a split pea, with a hair projecting in the center. These increase in size and become crusted over, so that the characteristic lesion
can only be seen round the edge of the scab
. Growth continues to take place for several months, when scab and scutulum
come away, leaving a shining bare patch destitute of hair. The disease is essentially chronic, lasting from ten to twenty years. It is caused by the growth of a fungus
, and pathologically is the reaction of the tissues to the growth.
The fungus was named after a microscopic structure termed "achorion" (a term not used in modern science), seen in scrapings of infected skin, which consists of slender, mycelial threads matted together, bearing oval, nucleated fungal substrate-arthroconidia either free or jointed. This structure is currently called "scutula." The fungus itself is now called Trichophyton
schoenleinii.
During initial infection, the fungal spores would appear to enter through the unbroken cutaneous surface, and to germinate mostly in and around the hair follicle
and sometimes in the shaft of the hair.
in 1839; the discovery was published in a brief note of twenty lines in Millers Archive for that year (p. 82), the fungus having been subsequently named by Robert Remak
; Achorion
schoenleinii after its discoverer.
In 1892, two additional "species" of the fungus were described by Paul Gerson Unna
, the Favus griseus, giving rise to greyish-yellow scutula, and the Favus sulphureus celerior, causing sulfur-yellow scutula of a rapid growth. This was in the days before scientists learned to rigorously distinguish microorganism identities from disease identities, and these antique, ambiguous disease-based names no longer have status either in mycology
or in dermatology
.
Similar looking infections, sometimes diagnosed as favus but more often as atypical inflammatory tinea, may rarely be produced by agents of more common dermatophyte fungal infections, in particular Microsporum gypseum, the most common soil-borne dermatophyte fungus, and Trichophyton mentagrophytes (name used in post-1999 sense for a phylogenetic species
formerly referred to as Trichophyton mentagrophytes var. quinckeanum), the agent of favus infection of the mouse.
, and European sufferers were sometimes committed to leprosaria. Today, due to this species' high susceptibility to the antifungal drug griseofulvin
, it has been eliminated from most parts of the world except rural central Asia and scattered rural areas of Africa. It is mainly a disease connected to demographic poverty and isolation, but is so readily treatable that it is among the diseases most likely to be completely eliminated by modern medicine.
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
usually affecting the scalp
Scalp
The scalp is the anatomical area bordered by the face anteriorly and the neck to the sides and posteriorly.-Layers:It is usually described as having five layers, which can conveniently be remembered as a mnemonic:...
, but occurring occasionally on any part of the skin, and even at times on mucous membrane
Mucous membrane
The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...
s.
Presentation
The uncomplicated appearance is that of a number of yellowish, circular, cup-shaped crusts (scutulaScutula
Scutula is a genus of lichenized fungi in the family Pilocarpaceae.-External links:*...
) grouped in patches like a piece of honeycomb, each about the size of a split pea, with a hair projecting in the center. These increase in size and become crusted over, so that the characteristic lesion
Lesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
can only be seen round the edge of the scab
Scab
Scab can refer to the following:* Scab, a hard coating on the skin formed during the wound healing reconstruction phase* Derogatory term for a strikebreaker, a person who works despite strike action or against the will of other employees...
. Growth continues to take place for several months, when scab and scutulum
Scutulum
A scutulum is a yellow, perifollicular, saucerlike or cup-shaped crust with a cheesy odor, composed of dense mats of mycelia and epithelial debris...
come away, leaving a shining bare patch destitute of hair. The disease is essentially chronic, lasting from ten to twenty years. It is caused by the growth of a fungus
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
, and pathologically is the reaction of the tissues to the growth.
The fungus was named after a microscopic structure termed "achorion" (a term not used in modern science), seen in scrapings of infected skin, which consists of slender, mycelial threads matted together, bearing oval, nucleated fungal substrate-arthroconidia either free or jointed. This structure is currently called "scutula." The fungus itself is now called Trichophyton
Trichophyton
The fungus genus Trichophyton is characterized by the development of both smooth-walled macro- and microconidia. Macroconidia are mostly borne laterally directly on the hyphae or on short pedicels, and are thin- or thick-walled, clavate to fusiform, and range from 4 to 8 by 8 to 50 um in size....
schoenleinii.
During initial infection, the fungal spores would appear to enter through the unbroken cutaneous surface, and to germinate mostly in and around the hair follicle
Hair follicle
A hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
and sometimes in the shaft of the hair.
Species
It was the first disease in which a fungus was discovered by J. L. SchönleinJohann Lukas Schönlein
Johann Lukas Schönlein was a German naturalist, and professor of medicine, born in Bamberg. He studied medicine at Landshut, Jena, Göttingen, and Würzburg...
in 1839; the discovery was published in a brief note of twenty lines in Millers Archive for that year (p. 82), the fungus having been subsequently named by Robert Remak
Robert Remak
-External links:*** in the Virtual Laboratory of the Max Planck Institute for the History of Science...
; Achorion
Achorion
Achorion is an obsolete genus of dermatophyte fungus.The species previously belonging to genus Achorion have been moved to other genera. Some notable species include:...
schoenleinii after its discoverer.
In 1892, two additional "species" of the fungus were described by Paul Gerson Unna
Paul Gerson Unna
Paul Gerson Unna, was a German physician specialized in dermatology and one of the pioneers in dermatopathology....
, the Favus griseus, giving rise to greyish-yellow scutula, and the Favus sulphureus celerior, causing sulfur-yellow scutula of a rapid growth. This was in the days before scientists learned to rigorously distinguish microorganism identities from disease identities, and these antique, ambiguous disease-based names no longer have status either in mycology
Mycology
Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, medicinals , food and entheogens, as well as their dangers, such as poisoning or...
or in dermatology
Dermatology
Dermatology is the branch of medicine dealing with the skin and its diseases, a unique specialty with both medical and surgical aspects. A dermatologist takes care of diseases, in the widest sense, and some cosmetic problems of the skin, scalp, hair, and nails....
.
Similar looking infections, sometimes diagnosed as favus but more often as atypical inflammatory tinea, may rarely be produced by agents of more common dermatophyte fungal infections, in particular Microsporum gypseum, the most common soil-borne dermatophyte fungus, and Trichophyton mentagrophytes (name used in post-1999 sense for a phylogenetic species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
formerly referred to as Trichophyton mentagrophytes var. quinckeanum), the agent of favus infection of the mouse.
Treatment
Up until the advent of modern therapies, favus was widespread worldwide; prior to Schönlein's recognition of it as a fungal disease, it was frequently confused with Hansen's disease, better known as leprosyLeprosy
Leprosy or Hansen's disease is a chronic disease caused by the bacteria Mycobacterium leprae and Mycobacterium lepromatosis. Named after physician Gerhard Armauer Hansen, leprosy is primarily a granulomatous disease of the peripheral nerves and mucosa of the upper respiratory tract; skin lesions...
, and European sufferers were sometimes committed to leprosaria. Today, due to this species' high susceptibility to the antifungal drug griseofulvin
Griseofulvin
Griseofulvin is an antifungal drug that is administered orally. It is used both in animals and in humans, to treat fungal infections of the skin and nails...
, it has been eliminated from most parts of the world except rural central Asia and scattered rural areas of Africa. It is mainly a disease connected to demographic poverty and isolation, but is so readily treatable that it is among the diseases most likely to be completely eliminated by modern medicine.