Snapshot A 10-year-old boy presents in the ED with his mother. He reports exploring a cave where he and his friends saw bats about seven days ago. He recalls being scratched on the face and upper extremities when he and his friends startled the bats. Physical exam was unremarkable. Patient was immediately given a dose of HRIG. Introduction Classification virus single-stranded (-) linear, bullet-shaped RNA virus enveloped rhabdovirus rabies Central nervous system infection travels to CNS via retrograde transport up nerve axons Negri bodies (image to the right) eosinophilic inclusion bodies in the cytoplasm of hippocampal nerve cells common in Purkinje cells of cerebellum Epidemiology appproximately 55,000 deaths worldwide annually (mostly Asia and Africa) US incidence - 83 reported cases from 1983-2015 25 of these assumed to be acquired abroad 8 were organ transplant recipients Transmission bat, racoon, skunk, and dog bites virus is present in nerves and saliva of symptomatic rabid animal virus travels from PNS to CNS via retrograde transport Presentation Symptoms has long incubation period (weeks to months) before symptom onset progression is from fever and malaise to agitation, photophobia, and hydrophobia to paralysis and coma finally, death once symptoms have presented, survival is rare Evaluation Usually a clinical diagnosis Rapid immunofluorescence detects antigen in corneal smear or skin biopsy PCR or viral culture taken from brain samples after death definitive diagnosis Negri bodies cerebral inclusions that are 100% diagnostic only found in 80% of cases Differential Herpes simplex encephalitis Seizure disorders Psychosis Tetanus Treatment Post-exposure prophylaxis wound cleansing vaccination with inactivated vaccine (4 doses over 14 days) human rabies immunoglobulin (HRIG) (1 dose) Prognosis, Prevention, and Complications Prognosis post-exposure prophylaxis (PEP) is highly successful must be administered promptly-within 6 days of infection usually fatal after neurologic symptoms have developed Prevention pre-exposure prophylaxis only for those who have professions that handle potentially infected animals work with the rabies virus in labs live in rabies-endemic areas protection is via inactivated vaccine