What is the role of serology in the diagnosis of rabies?

Updated: Jun 21, 2019
  • Author: Sandra G Gompf, MD, FACP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

Serum rapid fluorescent focus inhibition test (RFFIT) titer results are positive in 50% of rabies cases. Results of the CSF RFFIT are antibody-positive (2-25% of serum titer) after the first week of illness.

Detection of viral RNA from saliva using PCR assay and viral antigen from brain biopsy specimens yields 100% specificity. Viral antigen assessment involving nuchal skin that contains hair follicles and corneal touch impressions have sensitivities of 67% and 25%, respectively.

Rabies virus RNA may be detected via PCR in saliva, nuchal skin containing hair follicles, CSF, and urine. [20]

In true rabies cases, however, the rise in specific neutralizing antibodies is often not documented through an RFFIT, because the victims succumb to the disease prior to mounting a response. Serologic testing is more useful to ascertain serostatus in immunized animals and humans. [27]


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