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 as the host's immune system is unable to keep the mites under control.
Demodex is a genus of mite in the family Demodecidae. 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
thumb|upright=1.3|A 28-year-old man with demodicosis and electron micrograph of his skin showing a Demodex folliculorum, millimeters in length<!-- This is content from a predatory publisher (intechopen.com); recommend finding an alternative source for a comparable image, but I hesitate to remove the image at this time. -->
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 folliculorum has also been described. 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, American Staffordshire Terrier, Boston Terrier, Boxer, Chihuahua, Chow Chow, Shar-Pei, Collie, Dalmatian, Doberman Pinscher, Bulldog, French Bulldog, English Bull Terrier, Miniature Bull Terrier, German Shepherd, Great Dane, Old English Sheepdog, American Pit Bull Terrier, West Highland White Terrier, Rat Terrier, Yorkshire Terrier, Dachshund, 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
Dogs
For demodectic mange, properly performed deep skin scrapings generally allow the veterinarian to identify the microscopic mites. 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. Acetate tape impression of the skin is another method to identify mites. 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 productivity.
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.