Mange and Mites

This fact sheet was updated March, 2020.

Cause

Mange is a highly contagious skin disease of mammals caused by burrowing skin mites. There are three main types of mange, each caused by a different type of mite; sarcoptic mange is caused by Sacroptes scabiei, notoedric mange is caused by Notoedres centrifera, and demodectic mange is caused by two species of mite from the genus Demodex.

A fourth form of mange, psoroptic mange, is caused by Psoroptes cuniculi and affects rabbits and deer. Mites from the genus Knemidocoptes (most commonly K. pilae, K. mutans, and K. jamaicensis) infect only birds and cause clinical signs similar to mange.

Because the underlying mechanism by which the mites cause disease is the same and because sarcoptic mange is the most common and most studied in wildlife it will thus be the focus of this disease description.

Significance

Mites that cause sarcoptic mange are adapted to infect specific hosts, though they can also temporarily infect other species. There is a specific human-adapted variety of S. scabiei that causes the disease generally called scabies in people after direct contact with infected wildlife or pets. Occasionally, humans can become infected with animal varieties of S. scabiei and may develop a short-lived (10-14 days), self-limiting infection. Animal herders, slaughterhouse workers, wildlife biologists, veterinarians, wildlife rehabilitators, researchers, trappers, and pet owners are at greater risk of contracting this disease from infected animals.

Sarcoptic mange has led to the decline in fox and wolf populations in some areas of the United States and Europe.

Notoedric mange does not infect humans but is an important disease of domestic and wild cats as well as squirrels.

Demodex mites are mostly species specific but a few species of Demodex can affect closely related mammals. Demodex are normal inhabitants of the skin of all mammals but they can cause disease if the animal is immunocompromised or otherwise stressed (e.g. poor nutrition).  Occasionally there can be moderate to severe hair follicle damage and hair loss associated with disease caused by Demodex mites.

Knemidocoptes mites can cause severe damage to birds if not properly treated and are common in a variety of bird species, with a higher incidence reported in winter when birds are commonly fed and mortality can be an outcome.

Species Affected

Sarcoptic mange has been reported in over 100 species of wild and domestic mammals. In North America, sarcoptic mange is known to occur in wild canids such as red foxes, coyotes, gray wolves, and red wolves. Sarcoptic mange has also been reported in black bears, porcupines, rabbits, squirrels, raccoons, white-tailed deer, and feral swine.

Notoedric mange is known to occur in the western gray squirrel, eastern gray squirrel, and fox squirrel as well as bobcats.  

Demodectic mange has been reported in many mammalian species including white-tailed deer, mule deer, elk and black bears. A new larger species of Demodex mites aff­ecting white-tailed deer was described in 2007.

Psoroptic mange has been reported in white-tail deer, elk and bison but is uncommon, being most commonly found in livestock, including sheep, goats, cattle, and horses. It also aff­ects both domestic and wild rabbits.

Knemidocoptes mites aff­ect many species of wild and domestic birds, including golden eagles, snowy owls, great horned owls, and other raptors, woodpeckers, ducks, geese, swans, sparrows, robins, wrens, finches, canaries, chickens, turkeys and exotic captive bird species.

Distribution

Sarcoptic, notoedric, demodectic, psoroptic mange and Knemidocoptes mites have been detected on every continent except Antarctica.  

Transmission

Mange is transmitted when a susceptible host becomes infected by direct contact with an affected animal or a contaminated environment, like burrows or nests, where free-living mites can survive.

Sarcoptic mange mites burrow and form tunnels in the outer layer of the skin. The female mites lay their eggs within these tunnels and the eggs hatch into larvae in 3-4 days. The larvae then either move to the surface of the skin or remain in the tunnels. In another 3-4 days, the larvae develop into nymphs, which remain in the tunnels, wander onto the surface of the skin, or create new tunnels. The nymphs develop into adults within 5-7 days. The complete life cycle of a male takes 13-16 days and a female takes 18-23 days. Larvae and nymphs wandering on the surface of the skin can also fall o­ff the host and survive in the environment for several weeks in low temperatures and high relative humidity.

The life cycle and transmission of notoedric mites are similar to that of sarcoptic mites.

Demodex mites are diff­erent in that they naturally inhabit hair follicles and associated glands. These mites are acquired by an animal from their mother in the first few hours of life and remain in the hair follicles for the remainder of the animal’s life. Females lay eggs within the hair follicle that develop into larvae, nymphs, and then adults. A single follicle may contain many mites at diff­erent stages in their life cycle.

Psoroptic mites are confined to the surface of the skin. They pierce host tissue and feed on serum and other fluid secretions from the bite wound.

Knemidocoptes mites inhabit the feather follicles and outer skin layer of the face, feet and beak.

Clinical Signs

Clinical signs vary by the type of mite but common signs are itching and hair loss.

Animals with sarcoptic mange will often exhibit hair thinning and loss as well as intense itch.  The skin becomes variably thickened, wrinkled, and scabbed. In advanced disease there is often a foul-smelling musty odor due to overgrowth of normally occurring bacteria and yeast. Skin lesions can involve the entire body, though the ears and face are most commonly aff­ected. Severely aff­ected animals may become emaciated, depressed, lethargic, and may lose their fear of humans. When the skin around the eyes, mouth, and ears is involved, animals may experience visual impairment, difficulty eating, and hearing loss. Red foxes are typically the most severely aff­ected wild species and often die of this disease. Severely aff­ected bears will typically not den.

Squirrels with notoedric mange experience hair loss that starts at the chest and shoulders but can progress to aff­ect nearly the entire body. In the winter months, infections can be fatal due to the loss of the insulating layer of fur.

Demodex mites do not usually cause clinical illness in otherwise healthy animals. Clinical signs of demodectic mange occur in animals that are suff­ering from some combination of poor nutrition, concurrent disease, or a weakened immune system. Similar to other forms of mange, animals with demodectic mange can experience mild to moderate hair loss with dry, flaky, thickened skin. Larger species of Demodex may cause similar but more severe disease. Animals may also be in poor body condition.

Psoroptic mites cause hair loss, yellow crust and exudate formation on the skin of the affected animals. These mites are intensely itchy and can cause severe self-trauma and, in the case of deer, signs associated with ear infections such as a head tilt or abnormal gait.

Knemidocoptes mites cause crusty or scaly lesions on un-feathered skin, particularly on the skin around the beak and eyes, the feet, and legs. In severe cases, these areas may become permanently malformed. Mites that reside in feather follicles or the epidermis create pouch-like cavities, causing a honeycombed lesion. Certain species of Knemidocoptes mites cause birds to pick at their feathers, resulting in feather loss or secondary bacterial infection. These mites have also been linked to decreased egg production in certain species.

Diagnosis

A diagnosis is reached by microscopic identification of the mites in skin scrapings. Under the microscope, sarcoptic and notoedric mites appear round with short, stubby legs, while demodectic mites are cigar shaped.

In some cases, a presumptive diagnosis can be reached based on clinical signs such as the differences in appearance and distribution of hair loss which can help determine the type of mite responsible for the infestation.

Treatment

Medications (such as Ivermectin) are available that can be used to successfully treat mange, but they are not commonly used in free-ranging wildlife. Many a­ffected animals will resolve their mange without intervention if their immune system functions normally. 

Management

Management of mange and mites in wild populations by reducing the number of infected animals through hunting may not be e­ffective because the mites are likely widespread before animals are recognized with clinical illness. However, it is thought that mange is more likely to become established in high-density populations. Mange is a naturally occurring, common disease of wildlife, which makes control difficult. People handling animals with hair loss should wear gloves and should wash their hands thoroughly immediately after handling. In hunter-killed animals like deer, since the mites are confined to the skin and do not affect the muscle tissue, consumption of the infected animal does not pose a health risk.

Suggested Reading

Images

Life cycle of Sarcoptes scabieiLife cycle of Sarcoptes scabiei Image from Bornstein et al. 2001
Juvenile red fox with mangeJuvenile red fox with severe sarcoptic mange.Photograph by Karen Donahue, CVT
Bear with mangeBear with mange. Image credit: Michael Ondik
Head of bear affected by mangeHead of bear affected by mange. Image credit: Michael Ondik
Woodpecker affected by Knemidocoptes mites Woodpecker affected by Knemidocoptes mites. Image credit: Cynthia Crawford.