Rabies

For further information, see CMDT Part 32-03: Other Neurotropic Viruses

• A rhabdovirus infection causing encephalitis, transmitted by infected saliva after an animal bite

• Bats, raccoons, and skunks are most common vectors in the United States

• Other rabid animals include foxes, cats, cattle, and dogs

• Human cases rare in the United States

• Incubation period of 3–7 weeks, proportional to distance from wound to CNS

• Usually fatal unless patients receive postexposure prophylaxis

• Prodrome includes pain at site of bite, fever, nausea

• CNS symptoms (encephalitis or paralysis) begin about 10 days later

• Encephalitis: delirium and extremely painful laryngeal spasms that lead to hydrophobia

• Paralysis: less common; ascending paralysis resembles Guillain-Barré syndrome

• Both encephalitic and paralytic forms progress to coma, autonomic dysfunction, death

• Diagnosis suggested by history of animal bite, initial viral prodrome followed by CNS symptoms

• Diagnosis confirmed with fluorescent antibody testing of sacrificed animal brain

• Skin biopsy from the patient's posterior neck has ∼80% sensitivity

• Quantitative reverse transcriptase PCR (qRT-PCR), nucleic acid sequence-based amplification, direct rapid immunohistochemical test (DRIT) and viral isolation from the cerebrospinal fluid or saliva are advocated as definitive diagnostic assays

• Animal bite wounds should not be sutured

• Local wound cleansing, débridement, and flushes are useful

• Treatment includes both passive antibody and vaccination

• Single case report of treatment success with ribavirin, amantadine, plus midazolam

• A combination of rabies vaccine, rabies immune globulin, monoclonal antibodies (investigational), ribavirin, interferon-α, and amantadine may be helpful

• For suspected cases, use of postexposure immunization should be based on clinical guidelines, and on recommendations of local health officials

• Prevention

  • Immunization of household dogs

  • Avoidance of animals associated with rabies