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Test Id : POWVC

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Powassan Virus, RNA, Molecular Detection, PCR, Spinal Fluid

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Overview

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Useful For
Suggests clinical disorders or settings where the test may be helpful

Rapid testing for Powassan virus RNA (lineage 1 and lineage 2) using cerebrospinal fluid specimens

 

An adjunctive test to serology for detection of early Powassan virus infection (ie, first few days after symptom onset)

 

This assay should not be used for screening asymptomatic individuals and should only be used to test patients with signs and symptoms of Powassan virus disease.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Method Name
A short description of the method used to perform the test

Real-Time Polymerase Chain Reaction (PCR)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Powassan Virus, PCR, CSF

Aliases
Lists additional common names for a test, as an aid in searching

Powassan

Powassan virus

POWV

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Specimen Type
Describes the specimen type validated for testing

CSF

Ordering Guidance

The Powassan virus polymerase chain reaction result may remain positive for a longer time in urine than in blood, serum, and cerebrospinal fluid (7 days or more).

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Container/Tube: Sterile vial

Specimen Volume: 1 mL

Collection Instructions:

1. Send specimen from collection vial 2.

2. Do not centrifuge or heat inactivate.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T732) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.3 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Heat-inactivated specimen Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
CSF Refrigerated (preferred) 7 days
Frozen 7 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Rapid testing for Powassan virus RNA (lineage 1 and lineage 2) using cerebrospinal fluid specimens

 

An adjunctive test to serology for detection of early Powassan virus infection (ie, first few days after symptom onset)

 

This assay should not be used for screening asymptomatic individuals and should only be used to test patients with signs and symptoms of Powassan virus disease.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Powassan virus (POWV) is an emerging tick-borne virus, harbored by Ixodes species ticks, which are the same ticks that transmit Lyme disease (Borrelia spp.), Babesia spp., and Anaplasma phagocytophilum, among other pathogens. POWV is a member of the Flavivirus genus, which includes other arthropod-borne viruses (arboviruses) such as West Nile virus (WNV) and St. Louis encephalitis virus. Two lineages of POWV have been identified, sharing approximately 94% amino acid sequence identity, including lineage 1, which is the prototypical POWV lineage transmitted by Ixodes marxi and Ixodes cookei, and lineage 2, which includes deer tick virus and is transmitted by Ixodes scapularis. POWV is maintained in the environment in groundhogs, skunks, squirrels, and white footed mice. Unlike other tick-borne pathogens, following tick attachment to a host, POWV can be transmitted in as little as 15 minutes.

 

Following infection, the incubation period can last anywhere from 4 to 14 days, after which approximately 66% of patients will remain asymptomatic. Symptomatic patients may present with a nonspecific influenza-like illness, including high fever, fatigue, malaise, and myalgia. Approximately 30% of symptomatic patients will progress to develop neurologic manifestations, most commonly encephalitis. While some patients may recover, over 50% of individuals will have persistent neurologic sequelae. POWV has been associated with an overall mortality rate of 10%.

 

Although there is no targeted antiviral therapy and treatment is entirely supportive care, diagnosis is important for a number of reasons, including the ability to discontinue empiric antibiotics and to provide prognostic information for patients and families.

 

While limited data exist for POWV real-time reverse transcription polymerase chain reaction (RT-PCR) detection, data from testing for the related flavivirus, WNV, suggests that blood may be a more sensitive source than serum for detecting viral RNA. Similarly, data from WNV and other flaviviruses suggest that viral RNA may be detected in urine for a longer period of time than in blood or serum. POWV RNA may be detected from cerebrospinal fluid in cases of neuroinvasive disease.

 

Powassan infections are often diagnosed based on a patient's symptoms and exposure risk in conjunction with molecular and serologic testing. The use of RT-PCR can provide a rapid laboratory confirmation of POWV RNA early in infection, particularly during the first 7 days of illness when serologic testing is typically negative. After 7 days, POWV RT-PCR is less sensitive and serologic testing is the preferred diagnostic method. It is common for RT-PCR and serology to be used together for diagnosis of early infection, as they are complementary methods.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Negative

Interpretation
Provides information to assist in interpretation of the test results

A positive result indicates the presence of Powassan virus RNA and is consistent with early Powassan virus infection.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

The sensitivity of the assay is dependent upon the time of illness onset in which the specimen is collected. Polymerase chain reaction testing has the greatest utility when used within the first few days of symptom onset.

 

A negative test does not exclude infection with Powassan virus. Therefore, the results obtained should be used in conjunction with clinical findings and serologic test results to make an accurate diagnosis.

 

This assay detects both viable and nonviable virus. Test performance depends on viral load in the specimen and may not correlate with cell culture performed on the same specimen.

Supportive Data

The following validation data supports the use of this assay for clinical testing.

 

Accuracy/Diagnostic Sensitivity and Specificity:

Accuracy studies were performed by testing negative clinical specimens with whole viral genomic RNA for lineages 1 and 2 near the limit of detection (LOD) and yielded greater than or equal to 97% sensitivity and specificity.

 

Analytical Sensitivity/Limit of Detection:

The lower LOD of this assay is 1 to 52 target copies/mcL of RNA extract for EDTA whole blood and serum, 0.1 to 5.2 copies/mcL for urine, and 0.1 to 52 copies/mcL for cerebrospinal fluid.

 

Precision:

Interassay and intra-assay precisions are 100%.

 

Specificity:

A panel of 15 organisms that can be found in the specimen types acceptable for this assay, as well as closely-related viruses (eg, dengue types 1-4, Japanese encephalitis virus, hepatitis E virus, Murray Valley encephalitis virus, St. Louis encephalitis virus, tick-borne encephalitis virus, yellow fever virus, Zika virus) and those that can cause a similar clinical syndrome were tested by this assay. No cross-reacting positive results were noted.

 

Reportable Range:

This is a qualitative assay, and the results are reported as either negative or positive for targeted Powassan virus.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Centers for Disease Control and Prevention (CDC), National Center for Emerging and Zoonotic Infectious Diseases, Division of Vector-Borne Diseases: Powassan Virus. For Healthcare Providers: Diagnostic testing. CDC; Updated January 26, 2023. Accessed March 28, 2023. Available at www.cdc.gov/powassan/diagnostic-testing.html

2. Piantadosi A, Rubin DB, McQuillen DP, et al. Emerging cases of Powassan virus encephalitis in New England: Clinical presentation, imaging, and review of the literature. Clin Infect Dis. 2016 Mar 15;62(6):707-713. doi: 10.1093/cid/civ1005

Method Description
Describes how the test is performed and provides a method-specific reference

For this real-time reverse-transcription laboratory-developed polymerase chain reaction (PCR) assay, viral nucleic acid is extracted from specimens, followed by amplification and detection on the Roche LightCycler 480 instrument. This PCR assay has been optimized to detect a target sequence in the nonstructural protein. Primers amplify a 179 base pair product. Powassan virus genomic RNA is first transcribed to complementary DNA (cDNA) by reverse transcriptase, followed by amplification of the cDNA product. The LightCycler 480 is an automated instrument that amplifies and monitors the development of target nucleic acid (amplicon) after each cycle of PCR. The detection of amplicon is based on fluorescence resonance energy transfer, which utilizes a hybridization probe with a donor fluorophore, fluorescein, at the 3' end and a second hybridization probe with an acceptor fluorophore, LC-Red 610, at the 5' end. When the target amplicon is present, the LC-Red 610 emits a measurable and quantifiable light signal at a specific wavelength. Presence of the specific organism nucleic acid may be confirmed by performing a melting curve analysis of the amplicon. Using features of the melting curve analysis, the assay primers and specific hybridization probes are able to detect Powassan virus lineage 1 and lineage 2.(Unpublished Mayo method)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

Same day/1 to 5 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

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Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

87798

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
POWVC Powassan Virus, PCR, CSF 34457-2
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
617489 Lineage 1 34457-2
618145 Lineage 2 (Deer Tick Virus) 34457-2
618149 Powassan Virus PCR Comment 77202-0

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | PHP Pdf | CMS Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports