Now rare in North America and Western Europe, rabies remains comparatively common in Asia and some portions of southeastern Europe. Over 50 000 cases of rabies are reported to the World Health Organization annually. Worldwide, infected canines remain the major vector of human rabies. It is caused by a large single-stranded RNA containing a rod-shaped (rhabdo) lyssa group virus that is transmitted to humans from the saliva through bites or skin abrasions. Passage to the brain occurs via axonal transport through sensory and motor nerve fibers without an intervening viremia. The incubation period may be only a few days in the case of severe bites, particularly on the scalp and face, and is typically lengthy when the site of entry is in the lower extremities. As with herpes simplex encephalitis, rabies may initially manifest as an infection of the limbic regions of the brain. Characteristic symptoms and signs are dramatic and include agitated delirium, extremely high fevers, hypersalivation, and violent bouts of hydro- and aerophobia (phobic spasms). Less commonly, rabies may manifest as a Guillain-Barré syndrome (paralytic or dumb rabies) with relative preservation of sensorium. Survival after establishment of rabies within the brain and the onset of symptoms is exceptional. Presently, the focus of management is immediate provision of both passive and active immunization to individuals exposed or likely to have been exposed to a rabid animal ( Table... 2). Research continues to focus on bolstering the characteristically deficient immune response to infection and the possible role of 'excitotoxicity' (hyperstimulation of central nervous system glutamate receptors) in the clinical manifestations of encephalitic rabies. Management remains essentially supportive and comfort oriented.
Table 2 Rabies postexposure prophylaxis schedule
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