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 Rabies

Information for State Health Departments

Collection of Samples For Diagnosis of Rabies in Animals

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Testing for rabies in animals is done postmortem and may be necessary to determine the rabies exposure risk to humans. Samples requiring confirmation, variant typing, or formalin-fixed tissues may be sent to the CDC for additional diagnostic testing. The rabies laboratory should be contacted (404-639-1050) before any samples are submitted for testing.

Instructions for formalin-fixed Tissue

  1. Patient History
    If a human exposure is involved, include a complete patient history with all the known information regarding the exposure.
  2. Include reports on pathological findings by light microscopy of the H & E stained slides, if available.
  3. Submit H & E stained section from each paraffin block being submitted, ¹ to include brain stem, hippocampus, and cerebellum and other areas indicative of lesions.
  4. Submit 4 or 5 unstained sections - from each of these blocks mounted on coated slides.*
  5. Submit the paraffin blocks from which these slides were sectioned.
  6. Specimens must be placed in sealed mailing containers or bags put in a Styrofoam box or padded manila envelope, and shipped to:

    Rabies Laboratory
    DASH, Bldg 18, Room SSB218
    Centers for Disease Control and Prevention
    1600 Clifton Road, NE
    Atlanta, GA 30333
    (404) 639-1050

¹ If the submitting laboratory cannot provide unstained sections to CDC and provides paraffin blocks for FFFA testing, processing time will be one week.

Collection of Samples For Diagnosis of Rabies in Humans

State health departments should be the primary contact for physicians during consultation about possible human rabies cases. After consultation with physicians, it may be deemed necessary to send human samples for rabies testing to the Rabies Laboratory at the Centers for Disease Control and Prevention (CDC). Any questions regarding likelihood of a case, sampling techniques, and shipping can be answered by calling the Rabies Section at the CDC at (404)-639-1050.

Additional Resources

  1. Patient History
    Please make sure physicians complete associated form detailing the clinical history of the patient and provide the name and phone number of the physician who should be contacted with the test results in addition to state health department authorities. This form must accompany any samples sent to the Rabies Laboratory at the CDC. (Adobe PDF Icon Possible Human Rabies --Patient Information Form [PDF – 347 KB])
  2. Sample Shipment
    All samples should be considered as potentially infectious. Test tubes and other sample containers must be securely sealed (tape around the cap will insure that the containers do not open during transit). If immediate shipment is not possible, samples should be stored frozen at -20oC or below. Samples should be shipped frozen on dry ice by an overnight courier in water-tight primary containers and leak-proof secondary containers that meet the guidelines of the International Air Transport Association. The rabies laboratory at CDC should be telephoned (404-639-1050) at the time of shipment and given information on the mode of shipment, expected arrival time, and courier tracking number. Shipment address is as follows:

    Rabies Laboratory
    DASH, Bldg 18, Room SSB218
    Centers for Disease Control and Prevention
    1600 Clifton Road, NE
    Atlanta, GA 30333

  3. Sample Collection
    • Saliva
      Using a sterile eyedropper pipette, collect saliva and place in a small sterile container which can be sealed securely. No preservatives or additional material should be added. Laboratory tests to be performed include detection of rabies RNA (by reverse transcription and polymerase chain reaction, RT/PCR, of extracted nucleic acids) and isolation of infectious virus in cell culture. Tracheal aspirates and sputum are not suitable for rabies tests.
    • Neck Biopsy
      A section of skin 5 to 6 mm in diameter should be taken from the posterior region of the neck at the hairline. The biopsy specimen should contain a minimum of 10 hair follicles and be of sufficient depth to include the cutaneous nerves at the base of the follicle. Place the specimen on a piece of sterile gauze moistened with sterile water and place in a sealed container. Do not add preservatives or additional fluids. Laboratory tests to be performed include RT/PCR and immunofluorescent staining for viral antigen in frozen sections of the biopsy.
    • Serum and cerebral spinal fluid (CSF)
      At least 0.5 ml of serum or CSF should be collected; no preservatives should be added. Do not send whole blood. If no vaccine or rabies immune serum has been given, the presence of antibody to rabies virus in the serum is diagnostic and tests of CSF are unnecessary. Antibody to rabies virus in the CSF, regardless of the immunization history, suggests a rabies virus infection. Laboratory tests for antibody include indirect immunofluorescence and virus neutralization.
    • Brain Biopsy
      The rarity of rabies and the lack of an effective treatment make the collection of a brain biopsy unwarranted; however, biopsy samples negative for herpes encephalitis should be tested for evidence of rabies infection. The biopsy is placed in a sterile sealed container; do not add preservatives or additional fluids. Laboratory tests to be performed include RT/PCR and immunofluorescent staining for viral antigen in touch impressions.

      Postmortem diagnosis of rabies is made by immunofluorescent staining of viral antigen in touch impressions of brain tissue. Portions of the medulla (brain stem), the cerebellum, and the hippocampus should be frozen and shipped on dry ice to a public health laboratory or the CDC laboratory. Preservation of tissues by fixation in formalin is not recommended if rabies diagnosis is desired.


Page last modified: April 25, 2008
Content Source: National Center for Zoonotic, Vector-Borne, & Enteric Diseases (ZVED)