Rabies testing is a test generally done on animals (predominantly wild animals) when a person has been bitten.

Since the 1960s, the standard test for rabies

Rabies

Rabies is a viral disease that causes acute encephalitis in warm-blooded animals. It is zoonotic , most commonly by a bite from an infected animal. For a human, rabies is almost invariably fatal if post-exposure prophylaxis is not administered prior to the onset of severe symptoms...

 has been Direct fluorescent antibody

Direct fluorescent antibody

Direct fluorescent antibody is a laboratory test that uses antibodies tagged with fluorescent dye that can be used to detect the presence of microorganisms. This method offers straightforward detection of antigens using fluorescently labeled antigen-specific antibodies...

 test (dFA test). Because rabies is present in nervous tissue (and not blood like many other viruses), it's best to test for rabies in brain tissue. This test can only be done post-mortem.

The dFA test is the quickest, most reliable test available. This is important because treatment on the bitten victim must start as soon after infection as possible. Furthermore, treatment is painful, expensive and potentially debilitating making it even more important to get accurate and timely results.

In living humans, several tests are required to diagnose rabies because no single test is sufficient. Samples of saliva

Saliva

Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...

, serum

Blood plasma

Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...

, spinal fluid

Cerebrospinal fluid

Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...

, and skin biopsies

Biopsy

A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...

 of hair follicle

Hair follicle

A hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....

s at the nape of the neck are all tested.

Because the number and complicated nature of the tests, biting victims are sometimes advised to start treatment while waiting for the results.