Deer: The family Cervidae of 17 genera and 45 species occurring nearly throughout North America, South America, and Eurasia, on most associated continental islands, and in northern Africa. Wild populations of deer have been established through introduction by people in Cuba, New Guinea, Australia, New Zealand, and other places where the family does not naturally occur. They are slim, long-legged and best characterized by the presence of antlers. Their habitat is forests, swamps, brush country, deserts, and arctic tundra. They are usually good swimmers; some migrate seasonally. (Walker's Mammals of the World, 5th ed, p1362)Antlers: The horn of an animal of the deer family, typically present only in the male. It differs from the HORNS of other animals in being a solid, generally branched bony outgrowth that is shed and renewed annually. The word antler comes from the Latin anteocularis, ante (before) + oculus (eye). (From Webster, 3d ed)Wasting Disease, Chronic: A transmissible spongiform encephalopathy (prion disease) of DEER and elk characterized by chronic weight loss leading to death. It is thought to spread by direct contact between animals or through environmental contamination with the prion protein (PRIONS).Animals, Wild: Animals considered to be wild or feral or not adapted for domestic use. It does not include wild animals in zoos for which ANIMALS, ZOO is available.Sin Nombre virus: A species of HANTAVIRUS which emerged in the Four Corners area of the United States in 1993. It causes a serious, often fatal pulmonary illness (HANTAVIRUS PULMONARY SYNDROME) in humans. Transmission is by inhaling aerosolized rodent secretions that contain virus particles, carried especially by deer mice (PEROMYSCUS maniculatus) and pinyon mice (P. truei).Ruminants: A suborder of the order ARTIODACTYLA whose members have the distinguishing feature of a four-chambered stomach, including the capacious RUMEN. Horns or antlers are usually present, at least in males.MontanaHornsDisease Reservoirs: Animate or inanimate sources which normally harbor disease-causing organisms and thus serve as potential sources of disease outbreaks. Reservoirs are distinguished from vectors (DISEASE VECTORS) and carriers, which are agents of disease transmission rather than continuing sources of potential disease outbreaks.