| Pre-Approval | None |
| Supplemental Information Requested | Requested: Travel history, illness onset date, IgM test result for requested virus
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| Submittal Form | Specimens must be accompanied with a hard copy of the completed VRDL General Purpose Specimen Submittal Formāā (PDF) or a form generated in the VRDL Lab Web Portal. |
| Methodology (Commercial Test Name or Laboratory Developed Test (LDT)) | Plaque Reduction Neutralization Test or āPRNT" (LDT) (Diagnostic) |
| Reflex Testing | None |
| Acceptable Specimen Type(s) and Collection Method | Human specimens: - Serum: serum tubes (red top) or serum separator tubes (red/gray top)
- CSF: sterile collection tubes
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Minimum Volume Requestedā
| - Serum: 1 mL
- Whole blood in serum separator tubes: 5-8 mL
- CSF: 1 mL
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| Transport Medium (if using) | Not Applicable |
| Specimen Labeling | Each specimen tube must be labeled with at least two unique patient identifiers, e.g., patient full name and date of birth. |
| Storage & Preservation of Specimen / Shipping Conditions | - Serum: freeze or refrigerate specimens promptly after collection.
- Whole blood: refrigerate specimens promptly after collection. Do not freeze whole blood.
- CSF: freeze or refrigerate specimens promptly after collection.
Ship refrigerated specimens to VRDL on cold packs. Ship frozen specimens to VRDL on dry ice. |
Shipping Instructions | Work with your local public health department to ensure samples are packaged according to instructions for Biological Substance ā Category B (UN 3373) shipment. Ship specimens and a hard copy of the completed submittal forms to: CDPH VRDL ATTN: Specimen Receiving 850 Marina Bay Parkway Richmond, CA 94804 Phone: 510-307-8585
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| Turnaround Time | 16 Business Days |
| Limitations | Does not distinguish between dengue serotypes. Flavivirus antibodies are often cross-reactive. PRNT is performed with paired viruses that are closely related and geographically co-circulating. Results for both viruses are reported. Traditionally, where neutralizing antibodies are detected for both viruses, a four-fold difference in titer is presumed to indicate the identity of the exposure; however, due to the possibility of an anamnestic antibody response, single specimens are screened at low dilutions and identity is only reported when neutralization is detected for only one virus. Dual reactivity is reported as evidence of undifferentiated flavivirus exposure. Laboratory results with clinical and environmental correlation must be used together with current case definitions to confirm or rule out cases. |
| Additional Information | A convalescent specimen is recommended to help determine recency of infection. When submitted separately, be sure to identify the previously submitted specimen by the VRDL accession number so that the acute and convalescent specimens may be linked, tested to endpoint and interpreted as a pair. |
| VRDL Points of Contact | Medical and Epidemiology Liaisons: (510) 307-8585 or VRDL.submittal@cdph.ca.gov |