Rabies: Epidemiology, pathogenesis, and prophylaxis

Rabies is a viral zoonosis that causes approximately 50,000 to 100,000 deaths per year worldwide. Most deaths occur in developing countries. Dogs are the major vector, especially in developing countries. The virus is usually transmitted to humans by infected saliva through the bite of a rabid animal; the incubation period averages 30 to 90 d. Hyperexcitability, autonomic dysfunction, hydrophobia, and acrophobia are characteristic of encephalitic rabies, which accounts for 80% of cases. The paralytic form is characterized by flaccid paralysis in the bitten limb, which ascends symmetrically or asymmetrically. Once symptoms develop, the disease is invariably fatal. Animal rabies can be controlled by proper induction of herd immunity, humane removal of stray animals, promotion of responsible pet ownership through education, and enactment of leash laws. Preexposure vaccination with modern cell culture vaccine is recommended for people at high risk of exposure to rabies and for travelers who spend longer than 1 mo in countries where rabies is a constant threat, or who travel in a country where immediate access to appropriate care is limited. Postexposure prophylaxis consists of prompt and thorough wound cleansing and immunization with modern cell culture vaccine, together with administration of rabies immune globulin to those individuals who have not previously received preexposure prophylaxis.