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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
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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
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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
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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