What is the standard test to confirm rabies diagnosis in animals post-mortem?

• A. ELISA on serum
• B. PCR on saliva
• C. Direct fluorescent antibody test on brain tissue
• D. Virus isolation from urine

Answer: (C)

Detecting rabies after death relies on showing viral antigen in brain tissue. The direct fluorescent antibody test on brain tissue is the standard confirmatory method. In this test, fresh brain samples (often from the brainstem, cerebellum, and hippocampus) are smeared on slides and treated with fluorescein-labeled antibodies that bind rabies virus antigens. Under a fluorescence microscope, infected neurons illuminate, giving a clear positive result. This approach is highly sensitive and specific when proper samples are used and the lab follows safety and quality controls.

Other options don’t fit as reliably for post-mortem confirmation: testing serum with ELISA isn’t definitive for active infection after death and can reflect vaccination or past exposure rather than disease; PCR on saliva can detect viral RNA but its reliability varies after death due to sample quality and timing; virus isolation from urine isn’t a standard diagnostic method for rabies.