neurologic disorders
Rabies
Introduction
Rabies is a viral encephalitis transmitted by the saliva of infected bats and certain other infected mammals. Symptoms include depression and fever, followed by agitation, excessive salivation, and hydrophobia. Diagnosis is by skin biopsy with fluorescent antibody or polymerase chain reaction testing. Vaccination is indicated for people at high risk of exposure. Postexposure prophylaxis involves wound care and passive and active immunoprophylaxis and, if promptly and meticulously executed, almost always prevents human rabies. Otherwise, the disorder is almost universally fatal. Treatment is supportive. (See also Introduction to Brain Infections .) Rabies causes>55,000 human deaths worldwide annually, mostly in Latin America, Africa, and Asia, where canine rabies is endemic. In the US, vaccination of domestic animals has reduced rabies cases in people to<3 a year, mostly transmitted by infected bats. Infected raccoons, skunks, and foxes can also transmit rabies. Transmission of rabies to humans from small rodents (such as squirrels, chipmunks, rats, mice, hamsters, guinea pigs, gerbils) and lagomorphs (including rabbits and hares) has not been reported. Rabid animals transmit the infection through their saliva, usually by biting. Rarely, the virus can enter through a skin abrasion or across mucous membranes of the eyes, nose, or mouth. The virus travels from the site of entry via peripheral nerves to the spinal cord (or to the brain stem when the face is bitten), then to the brain. It then spreads from the central nervous system (CNS) via peripheral nerves to other parts of the body. Involvement of the salivary glands and oral mucosa is responsible for transmissibility. 