Demodex folliculorum
Encyclopedia
Demodex folliculorum is a species of face mite. D. folliculorum is one of the parasitic face mites that occur on people (other than Demodex brevis
). Demodex derives from the Greek roots, demos- fat, and dex- worm. When large numbers of D. folliculorum are found on humans, the infestation is known as "demodicosis".
, any skin disease caused by parasitic mites affecting animals. Tulk was the first to publish about Demodex in dogs. In 1842, a Frenchman name Berger discovered Demodex folliculorum in earwax. Demodex folliculorum was first discovered in human hair by a researcher at Nioxin, a major hair care and cosmetics manufacturer with a high powered, newly developed, hand-held microscope that was capable of magnifying the human scalp up to 1000 times. This magnification of the human scale allowed them to see the dozens of mites deep inside the hair follicles. The mites were found "eating" off the oil secretions of the scalp known as sebum. Nioxin Research Laboratories worked with Tulane University, and found that 88% of people with thin hair have Demodex folliculorum. On the other hand, only 9% of individuals with normal hair density had Demodex folliculorum.
s, normally found in greater numbers around the cheeks, nose, eyebrows, eyelashes, and forehead. They could also be found in other parts of the body such as arms, chest, and ears. It is a species of tiny mites that have been thought to contribute to hair loss (though this hypothesis is under debate) and live in our pores and hair follicles.
The mites vary in size from 0.1mm to 0.4mm long. Their food is mainly sebaceous secretions and dead cells, such as cytoplasm
. They do not defecate on the skin; however, they do reproduce on it. Mites do not invade internal organs.
of D. folliculorum takes places in the time span of 18–24 days on its host. Females have a ventral vulva anus opening, and males have a well-developed penis located between the first and second legs. A female adult lays 20-24 eggs in a single hair follicle, as they grow they become tightly packed, and develops into larvae. During the day, they remain feeding within the follicle. Later at night, they emerge onto the surface of the mate and eggs are laid into the hair follicles. The larva is then washed by a sebaceous flow, produced by the host’s sebaceous glands, into the mouth of the hair follicle where the egg matures into an adult. It takes seven days for the larva to develop into an adult that is ready to reproduce sexually.
Demodex brevis
Demodex brevis is one of the two species of face mite that afflict humans . They are very similar to the Demodex folliculorum, with just a few differences. They are usually found in the sebaceous glands of the human body. The same way that D. folliculorum reproduces on the follicles, D. brevis...
). Demodex derives from the Greek roots, demos- fat, and dex- worm. When large numbers of D. folliculorum are found on humans, the infestation is known as "demodicosis".
History
Demodex was first discovered in 1840 in dogs to cause mangeMange
Mange is the common name for a class of persistent contagious skin diseases caused by parasitic mites. Since mites also infect plants, birds, and reptiles, the term "mange," suggesting poor condition of the hairy coat due to the infection, is sometimes reserved only for pathological...
, any skin disease caused by parasitic mites affecting animals. Tulk was the first to publish about Demodex in dogs. In 1842, a Frenchman name Berger discovered Demodex folliculorum in earwax. Demodex folliculorum was first discovered in human hair by a researcher at Nioxin, a major hair care and cosmetics manufacturer with a high powered, newly developed, hand-held microscope that was capable of magnifying the human scalp up to 1000 times. This magnification of the human scale allowed them to see the dozens of mites deep inside the hair follicles. The mites were found "eating" off the oil secretions of the scalp known as sebum. Nioxin Research Laboratories worked with Tulane University, and found that 88% of people with thin hair have Demodex folliculorum. On the other hand, only 9% of individuals with normal hair density had Demodex folliculorum.
Parasitic behavior
These parasites are found in the human hair follicleHair 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....
s, normally found in greater numbers around the cheeks, nose, eyebrows, eyelashes, and forehead. They could also be found in other parts of the body such as arms, chest, and ears. It is a species of tiny mites that have been thought to contribute to hair loss (though this hypothesis is under debate) and live in our pores and hair follicles.
The mites vary in size from 0.1mm to 0.4mm long. Their food is mainly sebaceous secretions and dead cells, such as cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
. They do not defecate on the skin; however, they do reproduce on it. Mites do not invade internal organs.
Morphology
D. folliculorum is semi-transparent elongated organism consisting of a head, neck, body, and tail. D. folliculorum is worm-like, with tiny claws, and scales over their entire body, which allows it to anchor itself in the hair follicles. As an adult, D. folliculorum can measure 0.1 mm to 0.4 mm in length and possess four pairs of short legs near its head and neck region. However as a larvae and/or nymph, D. folliculorum resembles the adult but has three pairs of short legs near its head and neck region. The body and tail region of D. folliculorum is striated.Demodex folliculorum v. Demodex brevis
Both Demodex folliculorum and Demodex brevis are typically found on the human face. Demodex folliculorum resides in hair follicles, whereas Demodex brevis survives in sebaceous glands adjacent to hair follicles. For instance, around the eye area, Demodex folliculorum is found in the follicles of the eyelashes. In contrast, Demodex brevis inhabits the sebaceous gland of the eyelashes and the meibomian glands. Demodex brevis was first identified separate from Demodex folliculorum in 1963 by Akbulatova.Life cycle
The entire life cycleBiological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
of D. folliculorum takes places in the time span of 18–24 days on its host. Females have a ventral vulva anus opening, and males have a well-developed penis located between the first and second legs. A female adult lays 20-24 eggs in a single hair follicle, as they grow they become tightly packed, and develops into larvae. During the day, they remain feeding within the follicle. Later at night, they emerge onto the surface of the mate and eggs are laid into the hair follicles. The larva is then washed by a sebaceous flow, produced by the host’s sebaceous glands, into the mouth of the hair follicle where the egg matures into an adult. It takes seven days for the larva to develop into an adult that is ready to reproduce sexually.