Rabies differential diagnosis

The differential diagnosis in a case of suspected human rabies may initially include any cause of

• encephalitis
• particularly infection with viruses such as:
  • herpesviruses, enteroviruses
  • arboviruses(e.g., West Nile virus).
• The most important viruses to rule out are:
  • herpes simplex virus type 1
  • varicella-zoster virus
  • (less commonly) enteroviruses including:
    • coxsackieviruses
    • echoviruses
    • polioviruses
    • human enteroviruses 68 to 71.

• A specific diagnosis may be made by a variety of diagnostic techniques, including:
  • polymerase chain reaction (PCR) testing of:
  • cerebrospinal fluid
  • viral culture
  • serology.
• In addition, consideration should be given to the local epidemiology of encephalitis caused by arboviruses belonging to several taxonomic groups, including:
  • eastern
    • Western equine encephalitis viruses
    • St. Louis encephalitis virus
    • Powassan virus
    • The California encephalitis virus serogroup
    • La Crosse virus.

New causes of viral encephalitis are also possible, as was evidenced by the recent outbreak in Malaysia of some 300 cases of encephalitis (mortality rate, 40%) caused by Nipah virus, a newly recognized paramyxovirus. Similarly, well-known viruses may be introduced into new locations, as is illustrated by the recent outbreak of encephalitis due to West Nile virus in the eastern United States. Epidemiologic factors (e.g., season, geographic location, and the patient’s age, travel history, and possible exposure to animal bites, rodents, and ticks) may help direct the diagnostic workup.

References