What is a Dengue NS1 Test?
The Dengue NS1 Test is a blood test that helps in the early detection of dengue fever. It looks for a special protein called NS1 (Non-Structural Protein 1), which is released into the blood when the dengue virus is actively multiplying in the body.This test is usually done within the first 1–7 days of fever, when antibodies have not yet developed, making it one of the most reliable early tests for dengue.
What are the symptoms of dengue fever?
Dengue fever is a mosquito-borne viral infection. Its symptoms usually start 4–10 days after being bitten by an infected Aedes mosquito.
Common Symptoms of Dengue:
High fever (often 104°F or above)
Severe headache
Pain behind the eyes
Muscle, bone, and joint pain (sometimes called “breakbone fever”)
Nausea and vomiting
Skin rash (appearing 2–5 days after fever starts)
Fatigue and weakness
Severe Dengue (Dengue Hemorrhagic Fever) – Warning Signs:
Severe abdominal pain
Persistent vomiting
Bleeding gums or nosebleeds
Blood in urine, stool, or vomit
Difficulty breathing
Cold, clammy skin
What is Principle of Dengue NS1 Test?
The Dengue NS1 Antigen Test works on the principle of antigen detection.The dengue virus produces a special protein called NS1 (Non-Structural Protein 1) during the early phase of infection.This protein circulates freely in the patient’s blood serum within the first 1–7 days of fever.In the test, specific antibodies (already prepared in the test kit) bind with the NS1 antigen, if present.This antigen–antibody reaction is detected through a visible signal (color change, line, or agglutination), confirming the presence of the dengue virus.
What is Preparation of DENGUE NS1 Test ?
Lab Preparation for Dengue NS1 Test
A.Sample Collection:
Collect 3–5 ml venous blood → separate serum.
Avoid hemolyzed/contaminated samples.
B.Storage:
Test immediately or keep at 2–8°C (48 hrs) / -20°C (long-term).
C.Materials Needed:
Patient serum, NS1 kit (Rapid/ELISA), pipette & tips, timer, controls.
D.Reagent Prep:
Bring all reagents & samples to room temp (20–30°C).
Mix gently, avoid bubbles.
E.Quality Control:
Run positive & negative controls.
Calibrate pipettes, check expiry dates.
F.Safety:
Use gloves, lab coat, follow biosafety rules.
Dispose waste properly.
What is the DENGUE NS1 Test Procedure?
Dengue NS1 Test Procedure
1. Rapid Card Method (Point-of-Care Test)
Add 2–3 drops of patient serum/plasma/whole blood to the sample well.
Add 1–2 drops of assay buffer (if required).
Wait 15–20 minutes.
Interpret results:
Positive → Test line + Control line visible.
Negative → Only Control line visible.
Invalid → No control line.
2. ELISA Method (Lab Test)
Add patient serum and controls into ELISA plate wells coated with anti-NS1 antibodies.
Incubate at 37°C for 30–60 min.
Wash wells to remove unbound substances.
Add enzyme-labeled antibody → incubate → wash.
Add substrate → color develops if NS1 antigen present.
Stop reaction with stop solution.
Read OD values in ELISA reader (usually at 450 nm).
Rapid Test = quick screening (bedside/clinic). ELISA = confirmatory & quantitative (lab-based).
What are the limitations of the NS1 Test?
Limitations of Dengue NS1 Test
Early Detection Only
NS1 antigen is detectable mainly in the first 1–7 days of fever.
After that, test may turn negative even if the patient still has dengue.
Reduced Sensitivity in Secondary Dengue
In patients with previous dengue infection, antibodies may mask NS1, leading to false negatives.
False Positives
Cross-reactivity with other flaviviruses (Zika, Yellow Fever, West Nile virus).
Does Not Indicate Severity
A positive NS1 test confirms dengue infection but cannot predict if the patient will develop severe dengue / dengue hemorrhagic fever.
Not Useful Alone
Should be combined with IgM/IgG antibody tests, clinical symptoms, and CBC (platelet count, hematocrit) for accurate diagnosis.
Lab & Kit Variability
Sensitivity and specificity may vary depending on the brand of test kit and lab procedure.
How much does the DENGUE NS1 Test cost?
In major cities, the cost for dengue NS1 ELISA usually ranges from ₹500 to ₹800
Some rapid test variants can cost around ₹500
