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Mange in Black Bears By Mark Ternent, PGC Wildlife Biologist LAST FALL a trail-cam photograph of some sort of creature at the base of a tree in northern Pennsylvania gained widespread state, national, even internationl attention as the latest "big foot" sighting. Well, most certainly, the photograph was of a black bear with mange. What causes mange? There are two types of mange that can affect bears. Demodectic mange - sometimes called red mange in domestic animals - is caused by mites that live inside hair follicles, and sarcoptic mange, which is caused by mites that burrow into the skin. Mites are microscopic bugs similar to ticks and chiggers; they are part of the Arachnid (spider) family, as they lack a multi-segmented body, antennae and wings, and have more legs than true insects. The mites that cause demodectic mange occur naturally in all mammals, including humans. The species found on black bears is Demodex ursi. In most mammals, Demodex mites are transferred from mother to young during the first few hours of life. Once transferred, they migrate into hair follicles and remain there without causing problems for the remainder of the animal's life. However, if the animal's immunity system decreases because of malnutrition, disease, increased competition for resources or other environmental factors, Demodex mites can proliferate and demodectic mange develops. In dogs, some breeds have a genetic predisposition to demodectic mange, but it is unknown if a hereditary link occurs in black bears. It also is unknown if bears acquire Demodex mites by the typical mother-to-young pathway, or by some other route. Demodectic mange may appear as dry and scaly skin around the eyes and down the muzzle, or in severe cases, as swollen, hairless and thickened skin. Mild cases of demodectic mange may correct themselves if the animal's immune system returns to normal. For example, biologists visiting black bears in dens during the winter occasionally see dry scaly skin around the eyes and muzzle. Often, when these bears are handled again during the summer, the symptoms are gone. The presumption is that physiological stresses related to hibernation temporarily allowed the mild symptoms to develop. Unlike Demodex mites, which live in hair follicles, the mites that cause sarcoptic mange burrow into the skin. The primary species is Sarcoptes scabiei. Although classified as one species, several varieties of Sarcoptes scabiei exist; they look identical but live on different hosts. That is, the variety of Sarcoptes found on bears is different from the variety found on dogs. Sarcoptes varieties usually have a low degree of cross infectivity, meaning that the dog variety will typically not cause mange in bears and vice versa. Another burrowing mite, which is found exclusively on bears, is Ursicoptes americanus. Both species, Sarcoptes and Ursicoptes, have been found on bears in Pennsylvania. When Sarcoptes or Ursicoptes mites burrow into the skin, they create tunnels by ingesting cells or cutting tissue. They also produce secretions and deposit foreign materials such as their molted skin and eggs as well as dead mites. Although their burrowing damages the skin, mange also occurs because the body develops an allergic reaction to the secretions and foreign materials. The allergy causes intense itching, and repeated itching damages the skin, leading to bacterial infections, hair loss, and skin discoloration, thickening and crusting. Hair loss and skin debilitation may appear first on the face, elbows, ears or lower legs and then move up the legs and to the rear with the ridge of the back affected last. Bears with severe symptoms become emaciated, dehydrated, and eventually die from infection or starvation. Studies have reported that some animals that survive a mite infestation develop partial immunity to subsequent outbreaks, but it is unknown if such an immunity develops in black bears. Mite infestations can be treated with drugs that kill parasites. However, animals with large infestations require multiple treatments because mites reappear from eggs, which are not destroyed by the drugs. The Game Commission currently treats captured bears with mild to moderate mange symptoms, but typically euthanizes those with severe symptoms. HOW DO BEARS GET MITES? Mites can be transferred directly from animal to animal because the larvae and nymph stages of mites occasionally wander on the skin surface. Mites also can survive off of an animal, allowing them to be indirectly transferred through the environment. For example, researchers have documented that dens previously occupied by infected foxes can transfer mites to new foxes. The route of infection in bears is not clearly understood because bears are typically solitary (so there is minimal animal-to-animal contact) and rarely reuse nests or dens. However, any activity that brings bears into close contact with each other could facilitate the transfer of mites, thus, artificial feeding, which congregates wildlife, is discouraged. HOW IS MANGE DIAGNOSED? In domestic animals, treatment for mange may be started if hair-loss or skin symptoms are present, but verifying the presence of mites confirms the diagnosis. Mites can be detected by scraping or collecting skin and examining it under a microscope. However, even in animals that do have mange, mites may not be detected because they are burrowed deep in the skin or located somewhere other than where the skin sample was taken. In some cases, mange may be caused by a persisting allergic reaction even when very few mites remain on the animal. Tests that measure for allergic responses in blood are now available, but their use on bears has not been tested. IS MANGE DANGEROUS TO PEOPLE? Humans and pets can acquire Sarcoptes mites from bears, but the resulting infection is typically short-lived. Small bumps that itch intensely may develop on exposed skin or along areas constricted by clothing, such as the waistline, but mites do not burrow extensively and symptoms disappear within a few weeks in individuals with normal immune systems. Hunters are advised to not eat bears with moderate to severe symptoms, and are so advised when they bring their animals to a check station. Sightings of bears with severe mange should be reported to the nearest Game Commission office. IS MANGE IMPACTING PENNSYLVANIA'S BEAR POPULATIONS? Sarcoptic mange occurs worldwide in over 100 species of domestic and wild animals. Some wildlife species experience only isolated cases of mange, whereas others, such as foxes and coyotes, can have large outbreaks that lead to population declines. Sarcoptic mange is not presently believed to impact Pennsylvania bear populations, but it may affect local bear densities. Unfortunately, we do not have current estimates on how many bears die annually from mange, or if mortality is greater for a particular sex or age group. Each year in Pennsylvania between 15 and 20 bears are discovered dead or are euthanized with severe mange symptoms, and another 20 or more are trapped and released that have mild to moderate symptoms. At present, there are approximately 300 records in the Game Com-mission's black bear capture/mortality database that mention "mange," and they occur in about one-third of the primary bear range. However, there appears to be an increase in both the number of reports recorded each year and the number of townships affected. With the exception of Pennsylvania and Florida, very few eastern states report more than an occasional observation of mange in bears. Consequently, little research has been done. IS THE PGC STUDYING MANGE IN BEARS? In 1996, the Game Commission collected skin samples from bears during the hunting season to test for the prevalence of mites that cause mange. Sarcoptes and/or Ursicoptes were found on 1.6 percent of the bears harvested. This percentage is considered a minimum value because mites are notoriously difficult to detect by randomly sampling skin. In 2007, the Game Commission sampled bears at nine check stations to measure the prevalence of infected animals. This time, however, staff collected blood instead of skin. New methods of testing can detect the presence of a mite infestation with a blood test. A similar process was used in 1993 to study the prevalence of toxoplasmosis in Pennsylvania black bears. This data should provide a better estimate of the prevalence and distribution of mange in Pennsylvania black bears. The Game Commission will be testing the blood samples for other diseases as well, thereby investigating possible links between mange and other illnesses that may promote mange.