Demodex mite bite
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Demodicosis , also called Demodex folliculitis in humans and demodectic mange () or red mange in animals, is caused by a sensitivity to and overpopulation of '' Demodex spp.'' as the host's immune system is unable to keep the mites under control. ''
Demodex ''Demodex'' is a genus of tiny mites that live in or near hair follicles of mammals. Around 65 species of ''Demodex'' are known. Two species live on humans: ''Demodex folliculorum'' and ''Demodex brevis'', both frequently referred to as eyelash ...
'' is a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evid ...
in the
family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Demodecidae ''Demodecidae'' is a family of parasitic mites, living on various species of mammals. Each species of mite is usually only found on a single mammal species, whereas a mammal species can have several different species of demodecid mites living o ...
. The mites are specific to their hosts, and each mammal species is host to one or two unique species of ''Demodex'' mites. Therefore, demodicosis cannot be transferred across species and has no zoonotic potential.


Signs and symptoms


Humans

Demodicosis in humans is usually caused by '' Demodex folliculorum'' and may have a rosacea-like appearance. Common symptoms include hair loss, itching, and inflammation. An association with
pityriasis Pityriasis commonly refers to flaking (or scaling) of the skin. The word comes from the Greek πίτυρον "bran". Classification Types include: * Pityriasis alba * Pityriasis lichenoides chronica * Pityriasis lichenoides et varioliformis acut ...
folliculorum has also been described. Demodicosis is most often seen in folliculitis (inflammation of the hair follicles of the skin). Depending on the location, it may result in small pustules (pimples) at the base of a hair shaft on inflamed, congested skin. Demodicosis may also cause itching, swelling, and erythema of the eyelid margins. Scales at the base of the eyelashes may develop. Typically, patients complain of eyestrain.


Dogs

Minor cases of demodectic mange usually do not cause much itching but might cause pustules, redness, scaling, leathery skin, hair loss, skin that is warm to the touch, or any combination of these. It most commonly appears first on the face, around the eyes, or at the corners of the mouth, and on the forelimbs and paws. It may be misdiagnosed as a "hot spot" or other skin ailment. In the more severe form, hair loss can occur in patches all over the body and might be accompanied by crusting, pain, enlarged lymph nodes, and deep skin infections. Typically, animals become infected through nursing from their mother. The transmission of these mites from mother to pup is ''normal'' (which is why the mites are normal inhabitants of the dog's skin), but some individuals are sensitive to the mites due to a cellular immune deficiency, underlying disease, stress, or malnutrition,Ectoparasites - Demodex (Mange Mite)
Companion Animal Parasite Control (March 2013).
which can lead to the development of clinical demodectic mange. Some breeds appear to have an increased risk of mild cases as young dogs, including the
Afghan Hound The Afghan Hound is a hound that is distinguished by its thick, fine, silky coat and its tail with a ring curl at the end. The breed is selectively bred for its unique features in the cold mountains of Afghanistan. Its local name is ( ps, تاژ ...
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American Staffordshire Terrier The American Staffordshire Terrier, also known as the AmStaff or American Staffy is a medium-sized, short-coated American dog breed. The height of an American Staffordshire Bull Terrier is tall and weighs between . The American Kennel Club (AKC) ...
,
Boston Terrier The Boston Terrier is a breed of dog originating in the United States of America. This "American Gentleman" was accepted in 1893 by the American Kennel Club as a non-sporting breed. Color and markings are important when distinguishing this breed f ...
,
Boxer Boxer most commonly refers to: * Boxer (boxing), a competitor in the sport of boxing *Boxer (dog), a breed of dog Boxer or boxers may also refer to: Animal kingdom * Boxer crab * Boxer shrimp, a small group of decapod crustaceans * Boxer snipe ee ...
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Chihuahua Chihuahua may refer to: Places *Chihuahua (state), a Mexican state **Chihuahua (dog), a breed of dog named after the state **Chihuahua cheese, a type of cheese originating in the state **Chihuahua City, the capital city of the state **Chihuahua Mun ...
, Chow Chow, Shar-Pei, Collie, Dalmatian, Doberman Pinscher, Bulldog, French Bulldog,
English Bull Terrier The Bull Terrier is a breed of dog in the terrier family. There is also a miniature version of this breed which is officially known as the Miniature Bull Terrier. Appearance The Bull Terrier's most recognizable feature is its head, described ...
, Miniature Bull Terrier, German Shepherd, Great Dane, Old English Sheepdog,
American Pit Bull Terrier The American Pit Bull Terrier (APBT) is a dog breed recognized by the United Kennel Club (UKC) and the American Dog Breeders Association (ADBA), but not the American Kennel Club (AKC). It is a medium-sized, short-haired dog, of a solid build, ...
, West Highland White Terrier, Rat Terrier, Yorkshire Terrier,
Dachshund The dachshund ( or ; German: "badger dog"), also known as the wiener dog, badger dog, and sausage dog, is a short-legged, long-bodied, hound-type dog breed. The dog may be smooth-haired, wire-haired, or long-haired, and comes in a variety of c ...
, and Pug.


Cats

There are two types of demodectic mange in cats. ''Demodex cati'' causes follicular mange, similar to that seen in dogs, though it is much less common. ''Demodex gatoi'' is a more superficial form of mange, causes an itchy skin condition, and is contagious amongst cats.


Other

Demodectic mange also occurs in other domestic and wild animals, including captive pandas.


Diagnosis

For demodectic mange, properly performed deep skin scrapings generally allow the veterinarian to identify the microscopic mites. Acetate tape impression with squeezing has recently found to be a more sensitive method to identify mites. It was originally thought that because the mite is a normal inhabitant of the dog's skin, the presence of the mites does not conclusively mean the dog has demodicosis. Recent research, however, found that the demodex mite is rarely found on clinically normal dogs, meaning that the presence of any number of mites in a sample is very likely to be significant. In breeds such as the West Highland White Terrier, relatively minor skin irritation which would otherwise be considered allergy should be carefully scraped because of the predilection of these dogs to demodectic mange. Skin scrapings may be used to follow the progress of treatment in demodectic mange. Alternatively, plasma levels of zinc and copper have been seen to be decreased in dogs with demodicosis. This may be due to inflammation involved in the immune response of demodicosis which can lead to oxidative stress, resulting in dogs with demodicosis to exhibit higher levels of
antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...
productivity. The catalases involved in the antioxidant pathway require the trace minerals zinc and copper. Dogs with demodicosis show a decrease in plasma copper and zinc levels due to the increased demand for antioxidant activity. Therefore, this may be considered as a potential marker for demodicosis.


Treatment


Dogs

Localized demodectic mange is considered a common puppyhood ailment, with roughly 90% of cases resolving on their own with no treatment. Minor, localized cases should be left to resolve on their own to prevent masking of the more severe generalized form. If treatment is deemed necessary, Goodwinol, a rotenone-based insecticide ointment, is often prescribed, but it can be irritating to the skin. Demodectic mange with secondary infection is treated with
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
s and medicated shampoos. For more severe generalized cases, Amitraz is a parasiticidal dip that is licensed for use in many countries (the only FDA approved treatment in the USA) for treating canine demodicosis. It is applied weekly or biweekly for several weeks, until no mites can be detected by skin scrapings. Demodectic mange in dogs can also be managed with avermectins, although there are few countries which license these drugs, which are given by mouth daily, for this use. Ivermectin is used most frequently; collie-like herding breeds often do not tolerate this drug due to a defect in the
blood–brain barrier The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that prevents solutes in the circulating blood from ''non-selectively'' crossing into the extracellular fluid of ...
, though not all of them have this defect. Other avermectin drugs that can be used include doramectin and
milbemycin The milbemycins are a group of macrolides chemically related to the avermectins and were first isolated in 1972 from '' Streptomyces hygroscopicus''. They are used in veterinary medicine as antiparasitic agents against worms, ticks and fleas.
. Recent results suggest that the isoxazolines
afoxolaner Afoxolaner (INN) is an insecticide and acaricide that belongs to the isoxazoline chemical compound group. It acts as an antagonist at ligand-gated chloride channels, in particular those gated by the neurotransmitter gamma-aminobutyric acid ...
and
fluralaner Fluralaner (INN) is a systemic insecticide and acaricide that is administered orally or topically. The U.S. Food and Drug Administration (FDA) approved it under the trade name Bravecto for flea treatment in dogs in May 2014 and Bravecto Plus as a ...
, given orally, are effective in treating dogs with generalized demodicosis. Because of the possibility of the immune deficiency being an inherited trait, many veterinarians believe that all puppies with generalized demodex should be spayed or neutered and not reproduce. Females with generalized demodex should be spayed because the stress of the estrus cycle will often bring on a fresh wave of clinical signs.


Cats

Cats with ''Demodex gatoi'' must be treated with weekly or bi-weekly sulfurated lime rinses. ''Demodex cati'' are treated similarly to canine demodicosis. With veterinary guidance, localized demodectic mange can also be treated with a topical keratolytic and antibacterial agent, followed by a lime sulfur dip or a local application of Rotenone. Ivermectin may also be used. Generalized demodectic mange in cats is more difficult to treat. There are shampoos available that can help to clear dead skin, kill mites and treat bacterial infections. Treatment is in most cases prolonged with multiple applications.


References


External links

{{Mite-related diseases and infestations Dog diseases Arthropod infestations Parasitic infestations, stings, and bites of the skin