Rabies

Background
  • Almost always fatal (diagnosis frequently made postmortem)
  • Indication for prophylaxis:
    • Bite or salivary exposure from bat, or mammalian carnivore
    • Close proximity with unknown salivary exposure (e.g. live/dead bat in room)
  • Prophylaxis not needed if non-salivary exposure, or if bird, reptile, or rodent (rare cases)

Clinical Features

Clinical rabies is incredibly rare.

  • Incubation period = ~20-90 days, but may be shorter or longer

Encephalitic form
  • Hyperexcitability, disorientation, bizarre behavior, hallucinations
  • Autonomic dysfunction (e.g. hypersalivation)

Paralytic form
  • Paresis in bitten extremity → quadriparesis, bilateral facial weakness → coma, organ failure
  • Hydrophobia (50%) --> spasms of larynx, pharynx, diaphragm
  • Death from various complications: pituitary complications, respiratory dysfunction, cardiac dysfunction, autonomic dysfunction.

Differential Diagnosis

Jaw Spasms

Evaluation

Algorithm for Prophylaxis
Animal was captured

Is animal dog or cat?

  • Yes: Observe 10 days, if abnormal, sacrifice and treat patient with the vacc and RIG. Then patient treatment can be discontinued if the animal pathology is negative for rabies
  • No: Sacrifice animal and begin RIG and vaccine. Discontinue if animal negative path for rabies
Animal was not captured

Is Animal dog or cat?

  • Yes: Give vacc and RIG only if rabies risk for species in area
  • No: Treat with full course vacc and RIG

Management

Prophylaxis

Immunocompetent + NOT Vaccinated
  • Clean the wound (e.g. copious irrigation)
  • Rabies vaccine (human diploid cell vaccine)
    • 1mL IM on days: 0, 3, 7, 14[1]
    • Give in deltoid (not buttock), since Ab not created in fat cells
  • AND, Rabies immune globulin
    • 20 IU/kg subcutaneous
    • Infiltrate around wound if possible
    • place remainder opposite arm of vaccine
    • can administer up to 7 days after the first vaccine dose

Immunocompetent + Vaccinated
  • Clean the wound (e.g. copious irrigation)
  • Rabies vaccine (human diploid cell vaccine)
    • 1mL IM on days: 0 and 3
    • Give in deltoid (not buttock), since Ab not created in fat cells
  • NO rabies immune globulin

Immuno-compromised
  • Clean the wound (e.g. copious irrigation)
  • Rabies vaccine (human diploid cell vaccine)
    • 1mL IM on days: 0, 3, 7, 14, and 28[1]
    • Give in deltoid (not buttock), since Ab not created in fat cells
  • AND, Rabies immune globulin
    • 20 IU/kg subcutaneous
    • Infiltrate around wound if possible, except for digits and the penis
    • Place remainder opposite arm of vaccine
    • Can administer up to 7 days after the first vaccine dose

Disposition
  • Patient needing prophylaxis: outpatient
  • Clinical rabies: admit

See Also

References
  1. Use of a Reduced (4-Dose) Vaccine Schedule for Postexposure Prophylaxis to Prevent Human Rabies. http://www.cdc.gov/rabies/resources/acip_recommendations.html
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