''Microsporum gallinae'' is a

fungus A fungus ( : fungi or funguses) is any member of the 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, separately from t ...

of the genus ''

Microsporum ''Microsporum'' is a genus of fungi that causes tinea capitis, tinea corporis, ringworm, and other dermatophytoses (fungal infections of the skin). ''Microsporum'' forms both macroconidia (large asexual reproductive structures) and microconi ...

'' that causes

dermatophytosis Dermatophytosis, also known as ringworm, is a fungal infection of the skin. Typically it results in a red, itchy, scaly, circular rash. Hair loss may occur in the area affected. Symptoms begin four to fourteen days after exposure. Multiple a ...

, commonly known as ringworm. Chickens represent the host population of ''Microsporum gallinae'' but its

opportunistic Opportunism is the practice of taking advantage of circumstances – with little regard for principles or with what the consequences are for others. Opportunist actions are expedient actions guided primarily by self-interested motives. The term ...

nature allows it to enter other populations of fowl, mice, squirrels, cats, dogs and monkeys. Human cases of ''M. gallinae'' are rare, and usually mild, non-life-threatening superficial infections.

Taxonomy and naming

''Microsporum gallinae'' was first identified in 1881 by Megnin from chicken

favus Favus (Latin for " honeycomb") or tinea favosa is the severe form of tinea capitis, a skin infectious disease caused by the dermatophyte fungus ''Trichophyton schoenleinii.'' Typically the species affects the scalp, but occasionally occurs as ...

, and named ''Epidermophyton gallinae''. It was later transferred from the

Epidermophyton ''Epidermophyton'' is a genus of fungus causing superficial and cutaneous mycoses, including ''E. floccosum'', and causes tinea corporis (ringworm), tinea cruris (jock itch), tinea pedis Dermatophytosis, also known as ringworm, is a fung ...

genus, and classified in the

Trichophyton ''Trichophyton'' is a genus of fungi, which includes the parasitic varieties that cause tinea, including athlete's foot, ringworm, jock itch, and similar infections of the nail, beard, skin and scalp. Trichophyton fungi are molds characterize ...

genus, as ''T. gallinae''. The identification of rough-walled macroconidia, a hallmark of the

genus, lead to the

dermatophyte Dermatophyte (from Greek '' derma'' "skin" ( GEN ''dermatos'') and ''phyton'' "plant") is a common label for a group of fungus of ''Arthrodermataceae'' that commonly causes skin disease in animals and humans. Traditionally, these anamorphic (a ...

being classified as ''M. gallinae''. There is still debate about the

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

placement of this

, but the accepted name is ''Microsporum gallinae''. Analysis of its DNA sequences by PCR shows ''M. gallinae'' is most closely related to '' Microsporum vanbreuseghemii'' and '' Arthroderma grubyi'', both are also zoophilic fungi.

Distribution

''Microsporum gallinae'' is distributed throughout the world, with cases reported in: Europe, the Middle East, South America, North America, Africa and Japan. The

seems to be isolated more often in areas with high humidity and temperature.

Morphology

In culture, ''M. gallinae'' produces a white, satiny colony. The colony appears flat with radial folds and irregular edges as it grows in culture The colony reverse produces a strong pigmentation that changes from pink to a deep red and diffuses through the growth medium. Optimal growth of ''M. gallinae'' occurs at 26-28 °C, and no special nutritional requirements are necessary for its growth. Additionally, ''M. gallinae'' is urease positive. During sporulation, septate hyphae, with macroconidia with tappered tips, and club shaped microconidia are present. The addition of

thiamine Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thi ...

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...

extracts promotes sporulation of ''M. gallinae''. Hair invasion observed in ''M. gallinae'' is large spored ectothrix type, meaning that the spores form outside of the hair shaft.

Pathogenicity

''Microsporum gallinae'' is a cosmopolitan zoophilic fungi that very rarely affects humans. It obtains nutrients from keratin-rich skin, nails and hair, releasing enzymes during its digestion that elicit a host immune response as seen in

ringworm Dermatophytosis, also known as ringworm, is a fungal infection of the skin. Typically it results in a red, itchy, scaly, circular rash. Hair loss may occur in the area affected. Symptoms begin four to fourteen days after exposure. Multiple ar ...

. ''Microsporum gallinae'' infection is diagnosed by culturing the scrapings from skin lesions.

Chickens

''Microsporum gallinae'' causes a superficial infection that forms white lesions on the wattles and combs of chickens. Lesions may spread to the head and neck. The feathers are normally not affected by the

, although some feather loss can occur. Roosters and chicks tend to be more susceptible to the infection, with fighting cocks having the highest rates of ''M. gallinae''

. Although, it tends to resolve with treatment, the ''M. gallinae'' infection may become chronic. The lesions can also become infected with bacteria, complicating the infection. In some cases, it can resolve naturally without treatment; however, the infection may persist for weeks prior to clearance.

Humans

''Microsporum gallinae'' has been isolated from the scalp, and smooth skin in human populations. ''Microsporum gallinae'' infections are most commonly

tinea capitis Tinea capitis (also known as "herpes tonsurans", "ringworm of the hair", "ringworm of the scalp", "scalp ringworm", and "tinea tonsurans") is a cutaneous fungal infection (dermatophytosis) of the scalp. The disease is primarily caused by dermato ...

and

tinea corporis Tinea corporis is a fungal infection of the body, similar to other forms of tinea. Specifically, it is a type of dermatophytosis (or ringworm) that appears on the arms and legs, especially on glabrous skin; however, it may occur on any superficial ...

. Very few human cases of ''M. gallinae'' infection have been reported, none of which were life-threatening. Of the reported cases, individuals ranged from 3–96 years old. They had cutaneous lesions on the glabrous skin or the scalp. These localized lesions are frequently accompanied by itching. The cutaneous manifestations are very similar to those of ''

Microsporum canis ''Microsporum canis'' is a pathogenic, asexual fungus in the phylum Ascomycota that infects the upper, dead layers of skin on domesticated cats, and occasionally dogs and humans. The species has a worldwide distribution. Taxonomy and evolution ...

'' therefore many cases of ''Microsporum gallinae'' could have been unreported. In rare cases,

immunocompromised Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...

individuals form severe dissemination on the skin, instead of small localized lesions as a result of handling infected animals. Only one case of extensive

was reported involving ''M. gallinae'' infection of a person with AIDS.

Treatment

The treatment of ''M. gallinae'' involves both topical and oral

antifungals An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as cryp ...

. Topical antifungals, such as:

Terbinafine Terbinafine, sold under the brand name Lamisil among others, is an antifungal medication used to treat pityriasis versicolor, fungal nail infections, and ringworm including jock itch and athlete's foot. It is either taken by mouth or applied to ...

Tolnaftate Tolnaftate ( INN) is a synthetic thiocarbamate used as an anti-fungal agent that may be sold without medical prescription in most jurisdictions. It is supplied as a cream, powder, spray, liquid, and liquid aerosol. Tolnaftate is used to treat ...

, and orally administered

Griseofulvin Griseofulvin is an antifungal medication used to treat a number of types of dermatophytoses (ringworm). This includes fungal infections of the nails and scalp, as well as the skin when antifungal creams have not worked. It is taken by mouth. C ...

have been used successfully to treat ''M. gallinae'' infections in humans and animals.

References

{{Taxonbar, from=Q10584821 Arthrodermataceae Fungi described in 1881