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Dengue NS1

Dengue Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Dengue

Overview

The Dengue NS1 test detects the nonstructural protein 1 (NS1) antigen of dengue virus in blood; NS1 is produced and secreted by infected cells during active viral replication. The assay is used to identify acute dengue infection, especially in the early febrile phase (typically days 0–9 after symptom onset, most sensitive days 0–5). Clinicians suspect the test with acute fever, severe headache, retro-orbital pain, myalgia/arthralgia, rash, bleeding, abdominal pain, vomiting, or signs of plasma leakage. Test performance can vary by timing of sample, primary versus secondary infection, dengue serotype, age (children may present differently), and prior flavivirus immunity; sensitivity may be lower in secondary infections.

Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: Included in the "Dengue" diagnostic profile (acute dengue workup).
Symptoms prompting test: Acute febrile illness with headache, muscle/joint pain, rash, bleeding, abdominal pain, or hypotension.
Diagnoses/monitoring: Confirms acute dengue infection and helps guide early clinical management and monitoring for severe dengue.
Reasons for abnormal (positive) result: Active dengue viremia/antigenemia.
Biological meaning: Positive NS1 = circulating dengue antigen indicating active viral replication.
Contributors to abnormal results: Recent mosquito exposure or travel to endemic areas, timing of sample (early vs late), previous dengue or other flavivirus exposure may affect results.

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Understanding Test Results

A negative NS1 result (not detected) is expected in uninfected individuals or when testing occurs late (>7–9 days) after symptom onset, or in some secondary dengue infections where NS1 sensitivity is reduced.
A positive NS1 result indicates active dengue infection (antigenemia), most reliable within days 0–5 of illness and usually detectable up to about day 9.
Positive NS1 often correlates with higher viral load; early positivity warrants close clinical monitoring for progression to severe dengue (warning signs: persistent vomiting, abdominal pain, mucosal bleeding, lethargy, hepatomegaly, rising hematocrit with falling platelets).
False negatives can occur with late testing or secondary infections; false positives are uncommon but possible with other flavivirus exposure.
Negative NS1 does not fully exclude dengue—confirm with dengue PCR or paired IgM/IgG serology if clinical suspicion remains.

Normal Range

Negative (Not detected)

FAQs

Q: What does a positive NS1 Elisa mean for dengue?

A: A positive NS1 ELISA indicates dengue virus antigen is present in the blood and strongly suggests an acute, early dengue infection (usually within the first week of symptoms). It’s a reliable early diagnostic marker but doesn’t indicate disease severity or immune status. Confirmatory tests (PCR, IgM/IgG) and clinical assessment guide management. Patients with a positive NS1 should be monitored closely for warning signs and receive supportive care.

Q: Is dengue NS1 serious?

A: Dengue NS1 is a viral protein detected early in infection and indicates acute dengue. Its presence alone doesn't predict severity, although higher NS1/viral load can correlate with worse outcomes. Disease severity depends on immune status, prior infections and clinical warning signs (bleeding, severe abdominal pain, persistent vomiting, rapid breathing, low urine output, dizziness). If NS1 positive, seek prompt medical evaluation and monitoring.

Q: What is a normal dengue NS1 result?

A: A normal dengue NS1 result is negative no NS1 antigen detected, meaning no evidence of acute dengue infection at the time of testing. NS1 is most reliably positive during the first five days of fever, so a negative result does not completely rule out dengue. If symptoms continue or testing was later, clinicians may repeat testing or use IgM/IgG antibody tests.

Q: What is the cost of Elisa dengue NS1?

A: Cost of an ELISA dengue NS1 test varies by country and facility: in India it typically runs about ₹300–1,500 (~$4–20), in the United States about $30–150, and in the UK testing is free on the NHS or £30–100 privately. Prices depend on the lab, whether a rapid vs. ELISA method is used, and any consultation or reporting fees.

Q: How early can NS1 detect dengue infection?

A: The NS1 antigen can be detected very early—often from day 1 of fever and commonly during the first 5 days of illness. Sensitivity is highest in the first 3–5 days and may remain detectable up to about day 7–9 in some cases. After about day 5 antibodies (IgM/IgG) rise and NS1 levels usually decline, reducing test sensitivity.

Q: How long does NS1 stay positive in dengue?

A: NS1 antigen is usually detectable in blood from the first day of fever through about days 5 to 7 of dengue illness, allowing early diagnosis. In some patients it can remain positive up to around day 9, but sensitivity declines as antibodies (IgM and IgG) develop, especially in secondary infections. After the first week, antibody tests are more reliable for confirming dengue.