Rabies Virus

  • Diagnosis
  • Background
  • Lab Tests
  • References
  • Related Topics

Indications for Testing

  • Symptoms compatible with disease and no other known etiology; history of animal bite that was not treated with rabies immunoglobulin

Laboratory Testing

  • Rabies diagnosis information (CDC)
  • Disease is frequently not recognized until after death
  • Antemortem – CSF, salivary or virus-specific fluorescent material in skin biopsies taken from the nape of the neck; recent polymerase chain reaction (PCR) using saliva, tears and skin biopsy
  • Postmortem – presence of Negri bodies by direct visualization or direct immunofluorescence on brain biopsy; antibody testing of the brain


  • Antemortem – corneal impression for the presence of viral antigens

Differential Diagnosis

Rabies is a fatal viral zoonosis that causes 750,000 deaths worldwide each year.


  • Incidence – <100 cases each year in the U.S.; disease is endemic in Africa and Asia
    • >55,000 cases each year worldwide (WHO 2002)
  • Transmission – saliva from the bite of an infected animal; recently, transmission via tissue/organ transplantation; on rare occasions, transmission via aerosol droplets (lab accidents)
    • In the U.S., the most commonly infected animals are bats, raccoons, skunks and foxes
    • Infection by native dogs is uncommon in the U.S.
    • Worldwide infections – 54% from dogs, 42% from wildlife, 4% from bats


  • Single-stranded RNA virus
  • Member of the Rhabdoviridae family
  • Virus has predilection for nerve tissue, muscles and salivary glands
  • Virus spreads via peripheral nerves to the brain, causing encephalomyelitis

Clinical Presentation

  • Three phases of disease – prodromal, furious, paralytic
  • Incubation period – 2 weeks to 6 years (average is 2-3 months)
  • Prodromal phase
    • Loss of appetite, headache, myalgias
  • Furious phase (anterior horn cell dysfunction)
    • Fever, insomnia, photophobia, dysarthria, difficulty swallowing, hydrophobia
  • Paralytic phase (peripheral nerve dysfunction)
    • Flaccid, ascending paralysis
    • No hydrophobia
    • Death within 5 days at this stage if ICU support not available


  • Clean wound
  • Rabies vaccine (days 0, 3, 7, 14, 28 in deltoid only) plus rabies immunoglobulin infiltrated around wound at a dose of 20 IU/kg in a previously unvaccinated patient
    • If not given the first day of exposure, immunoglobulin can be infiltrated up to 7 days after first vaccine dose
  • Rabies vaccine (days 0 and 3) in a previously vaccinated patient
  • Once the patient is symptomatic, vaccination does not improve prognosis and treatment is symptomatic
  • <10 cases of survival from symptomatic rabies reported in the literature
    • Two most recent survivors demonstrated high serum and CSF neutralizing antibody titers shortly after hospital admission without virus isolation
      • Suggests that patients were able to produce antibodies against rabies virus


  • Rabies cannot be treated; therefore, prevention is essential
    • Immunization of pets
    • Pre-exposure prophylaxis in high-risk populations (veterinarians, animal handlers, lab personnel who handle the virus)
      • Rabies vaccine – should have IgG testing to evaluate immunization status with repeat every 6 months if in high-exposure job
    • Immediate post-exposure prophylaxis
Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Rabies Antibody, IgG (Vaccine Response) 0099132
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay


Intended for vaccine response only, not for diagnosis of infection

General References

Hemachudha T, Ugolini G, Wacharapluesadee S, Sungkarat W, Shuangshoti S, Laothamatas J. Human rabies: neuropathogenesis, diagnosis, and management. Lancet Neurol. 2013; 12(5): 498-513. PubMed

Jackson AC. Rabies. Neurol Clin. 2008; 26(3): 717-26, ix. PubMed

Wacharapluesadee S, Hemachudha T. Ante- and post-mortem diagnosis of rabies using nucleic acid-amplification tests. Expert Rev Mol Diagn. 2010; 10(2): 207-18. PubMed

Woldehiwet Z. Clinical laboratory advances in the detection of rabies virus. Clin Chim Acta. 2005; 351(1-2): 49-63. PubMed

Yousaf MZ, Qasim M, Zia S, Khan Mu, Ashfaq UA, Khan S. Rabies molecular virology, diagnosis, prevention and treatment. Virol J. 2012; 9: 50. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology®

Medical Reviewers

Last Update: August 2016