Rabies is caused by a bullet-shaped virus of the genus Lyssavirus in the family Rhabdoviridae. Rabies is an ancient viral infection of the central nervous system and is considered one of the oldest diseases transmissible to humans. The rabies virus was first isolated by Louis Pasteur in 1885 and he was the first scientist to produce the rabies vaccine. Because it is an enveloped virus, rabies is inactivated by varying concentrations of formalin, halogens, phenols, alcohols, mineral acids, and other disinfectants. Rabies virus particles are also extremely labile when exposed to ultraviolet light and heat. All warm-blooded animals are susceptible to rabies infection, but mammals are the only known vectors and reservoirs in nature. Wild animals that are common sources of rabies in the United States are skunks, raccoons, foxes, coyotes, and some bats found primarily in the southern United States down to Mexico. Human exposure to rabies occurs primarily through contact with infected domestic animals rather than wild animals. The virus is almost always transmitted to animals through the bite of an animal infected with rabies. Viral particles are carried in the saliva of infected animals and can be introduced into the body via a bite, through a scratch or open wound, or through intact mucous membranes. It is suggested that transmission from excreted or exhaled virus occurs between animals in very large colonies, such as bats. Airborne infection is thought to be more likely to occur when large quantities of aerosolized virus are present in poorly ventilated areas. Rabies can also be contracted through ingestion of infected tissue or secretions, but this is not very common. Rabies is a fatal disease and death usually occurs ten days after the onset of clinical symptoms. bite. This major source of rabies can be eliminated by ensuring adequate vaccination and control of animals, educating those at risk, and improving access to medical care for those bitten. Vaccination of animals, especially dogs, has reduced the number of human and animal rabies cases in several countries. Pre-exposure immunization is also recommended for people in certain high-risk occupations, such as laboratory workers handling live rabies virus, veterinarians, animal health technicians or custodians, and people involved in any activity that could bring them into direct contact with bats, carnivores and other mammals in rabies-affected areas. Pre-exposure vaccination is an initial series of three doses administered intramuscularly on days zero, seven, twenty-one, or twenty-eight. It has been shown to provide superior protection when followed for ten years