Rabies: Epidemiology, pathogenesis, and prophylaxis

Rabies is a viral zoonosis that causes approximately 55,000 deaths per year worldwide. Over 99% of these deaths occur in developing countries and in children less than 15 years old. Globally, dogs are the major vectors, although wild carnivores and bats are important vectors in developed countries. The virus is usually transmitted to humans by infected saliva through the bite of a rabid animal. The average incubation period is 30 to 90 days. Hyperexcitability, autonomic dysfunction, hydrophobia, and aerophobia are characteristic of encephalitic rabies, which accounts for 80% of cases. Alternatively, the paralytic form is characterized by flaccid paralysis in the bitten limb, which ascends symmetrically or asymmetrically. However, once encephalopathic or paralytic symptoms develop, the disease is invariably fatal. Consequently, effective prevention of rabies is the key approach to this disease. Rabies in animal vectors can be prevented by proper induction of herd immunity, humane removal of stray animals, promotion of responsible pet ownership through education, and enactments of leach laws. Preexposure vaccination with modern cell culture vaccine is recommended for people at high risk of exposure to rabies and for travelers spending longer than 1 month in countries where rabies is a constant threat, or traveling in a country where immediate access to appropriate care is limited. Post-exposure 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.