Introduction

Rabies virus is a pathogen well-adapted to the mammalian nervous system, where it infects the neurons. It causes rabies, an acute myeloencephalitis that is fatal in most mammalian species and humans in particular. Rabies virus is transmitted by saliva of an infected animal through bites or scratches or by unfortunate transplantation of organs from unsuspected rabid donors. Rabies virus enters the nervous system via a motor neuron through the neuromuscular junction or via a sensory nerve through nerve spindles. It then travels from one neuron to the next along the spinal cord to the brain. It causes behavior changes such as a furious state in dogs, loss of natural shyness in wild animals, or spectacular hydrophobia in humans. After brain invasion, the virus reaches the salivary glands where virions are excreted in the saliva. In the meantime, virus spreads to several peripheral organs of digestive, pulmonary, and urinary systems. Once the virus enters the central nervous system, no therapeutic treatment can battle the infection, and rabies is almost invariably fatal. Successful invasion of the nervous system by rabies virus seems to be the result of a subversive strategy based on the survival of infected neurons. However, rabies can be prevented by prompt post-exposure treatment with injection of killed rabies vaccine along with rabies-specific immunoglobulins. Postexposure treatment of rabies requires public information, access to medical facilities, and availability of efficient postexposure rabies vaccine, which are lacking in most parts of the world.