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Serum or plasma concentration of viral RNA (e.g., West Nile virus)

Published: August 9, 2026Updated: August 16, 2026

This test detects genetic material from West Nile virus in your blood or plasma. It helps determine if you have an active infection.

Quick summary

["Helps diagnose recent West Nile virus exposure by checking for its RNA in your blood."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
31701-6
Short code
WNV IgG Ser Ql
Synonyms
WNV IgG Ser Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What This Test Measures

The test looks for the presence of West Nile virus RNA, which is a type of genetic material found in the virus. If the virus is active in your body, its RNA will be detected in your blood or plasma sample.

Why It’s Done

Your healthcare provider may order this test if you have symptoms like fever, headache, body aches, or neurological issues (such as confusion, weakness, or seizures) that could be linked to West Nile virus infection, especially after exposure to mosquitoes in endemic areas.

What to Expect Before the Test

No special preparation is needed. You may have a blood draw from a vein in your arm, similar to other blood tests. If you’re concerned about needles, let your healthcare provider know.

What the Results Mean

Positive results indicate active West Nile virus infection. Negative results mean the virus RNA was not detected in this sample, but you may still have an infection if symptoms persist or if testing was done too early.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

West Nile Virus RNA (Serum/Plasma)

Frequently asked questions

How soon after exposure can this test detect West Nile virus?
West Nile virus RNA may be detectable in blood as early as 3–5 days after infection, but results can vary. Testing too soon may yield false negatives, so follow-up testing may be needed if symptoms develop.
Can this test be done on urine or saliva instead of blood?
No, this test specifically checks for viral RNA in serum or plasma. Urine or saliva tests are not used for this purpose.
What if my results are positive but I feel fine?
A positive result means the virus is active in your body, even if you’re asymptomatic. Some people may not experience symptoms until days or weeks later. Follow up with your healthcare provider for further evaluation.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy