Rabies

Abstract

Rabies is an acute encephalomyelitis of humans and animals caused by rabies virus, which is usually transmitted by an animal bite. Rabies has a very rich history. Worldwide, dogs are the most important vector, whereas wild animals, especially bats, are the main threat to humans in North America. After a delay at the site of entry, rabies virus spreads through the nervous system by fast axonal transport. Rabies can be effectively prevented after a recognized animal exposure with wound cleansing and administration of rabies vaccine and rabies immune globulin. Rabies typically develops after an incubation period of 20–90 days. Rabies has encephalitic and paralytic forms of disease and rabies is almost universally fatal after clinical onset. Hydrophobia is a characteristic clinical feature of encephalitic rabies. Pathologic changes include the presence of eosinophilic inclusions called Negri bodies in the cytoplasm of neurons and inflammatory changes. Imaging studies may be normal and do not show specific abnormalities. An antemortem laboratory diagnosis can be made with the detection of rabies virus antigen or RNA in tissues (e.g., skin) and/or body fluids (e.g., saliva) and with serologic testing. There is no known effective therapy for rabies, although there have been rare survivors.