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viral and rickettsial disease laboratory

VRDL Guidelines for Specimen Collection and Submission for Pathologic Testing

The CDPH Viral and Rickettsial Disease Laboratory (VRDL) provides diagnostic and confirmatory testing of ante-mortem and post-mortem specimens where there is suspect viral etiology.  Polymerase chain reaction (PCR) testing is the primary diagnostic method at VRDL and can be performed on swabs in viral transport media (VTM), nasopharyngeal washes and aspirates, and tissues.  The collection of appropriate specimens at the time of autopsy is very important to facilitate post-mortem diagnosis.  Since the distribution of respiratory tract viruses is highly variable, both lower and upper respiratory tract specimens should be obtained to ensure that virus is detected.

Respiratory Specimens


A nasopharyngeal swab, wash, or aspirate is an acceptable specimen for PCR testing.  Oropharyngeal (throat) swabs are also acceptable, but may not have as high of a yield.  If oropharyngeal specimens are collected, they should be accompanied by a specimen from the nasal cavity.


Suitable specimens include swabs of the lung, bronchi, or respiratory pathway.  Pleural fluid is also an acceptable specimen.

Specimen Storage:

Only swabs composed of synthetic fibers (e.g. rayon, nylon, dacron) should be used to collect samples.  The swabs should be placed in a standard container with 2-3 ml of VTM or similar media approved for viruses.  The specimens should be kept refrigerated at 4 ºC after innoculation.  If there will be prolonged specimen storage (>5 days), then the specimen should ideally be frozen at -70 ºC or below.

Tissue Specimens

The required specimens for testing at the VRDL are fresh frozen tissue collected from representative sites in the lower respiratory tract.  Wet fixed tissue in formalin and/or paraffin-embedded tissue blocks can also be submitted and may be tested at the VRDL as well as forwarded to the CDC. 

Respiratory tissue from the following sites should be collected:

  • Central (hilar) lung with semental bronchi
  • Right and left primary bronchi
  • Proximal and distal trachea
  • Representative tissue from pulmonary parenchyma

In cases with significant associated clinical symptoms, please submit representative tissues for further evaluation.  Of interest are cases in which there is suspicion of encephalitis, myocarditis, or gastrointestinal symptoms.  In each instance, please submit:

  • Encephalitis – CSF, cerebral cortex, basal ganglia, pons, medulla, cerebellum
  • Myocarditis – right and left ventricle tissue
  • Rhabdomyalysis – muscle tissue

Specimen Storage

Wet formalin-fixed tissue and paraffin-embedded blocks can be kept at room temperature.  Fresh tissue should ideally be frozen at -70 °C, but it may be acceptable to temporarily store the tissue in a -25 °C freezer until the specimens can be shipped to the VRDL.

Specimen Submission

All samples to be submitted to the VRDL must be accompanied by this VRDL specimen submittal form: General Purpose Specimen Submittal Form (PDF). Handwritten General Purpose Specimen Submittal Forms will not be accepted. The submittal form must be filled out as completely as possible and include supporting clinical information such as:

  • Clinical summary of the case including the name of the hospital where medical care was received
  • Medical records
  • Pathology report
  • Preliminary or final autopsy reports (required for specimen submission to the CDC)

Package and Transport

Specimens should be sent by an overnight courier according to the storage temperature.

  • Preserved specimens (fixed/paraffin blocks) can be sent at room temperature, but cold packs are recommended in warmer weather
  • Refrigerated specimens can be sent on 1-2 cold packs
  • Frozen specimens should be sent on dry ice

All shipments must meet the IATA packing instructions 650 and have outer packaging labels to designate the package as a “UN3373” and “Biological Substance Category B” shipment. If the package is shipped with dry ice, a Class 9 Dry Ice UN1845 hazard label must also be filled out and attached to the package. Please refer to the shipping protocols of your courier for additional requirements or more information.


All packages should be addressed to:

California Department of Public Health - VRDL  
ATTN: Specimen Receiving
850 Marina Bay Parkway   
Richmond, CA 94804     

For questions, please call the VRDL Medical Epidemiology Liaison Section at (510) 307-8585.


If you are having difficulty accessing the General Purpose Specimen Submittal Form (PDF) please contact CDPH at (510) 307-8585 to request this information in an alternate format. We are currently in the process of converting this document to ADA web accessible formats. ​

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