ELISA NS1 antigen for dengue is a blood test that detects the viral NS1 protein produced during acute infection. Using an enzyme-linked immunosorbent assay, it identifies infection early (usually within the first 0–7 days), enabling prompt diagnosis. It’s most useful in the acute phase and is often used alongside antibody tests (IgM/IgG) to confirm or stage infection.

Most dengue ELISA kits report results as an index (absorbance ratio). Typical interpretation: index <0.9 = negative, 0.9–1.1 = equivocal/borderline, >1.1 = positive. This applies to IgM and IgG ELISAs; NS1 ELISA is usually reported qualitatively. Cutoffs can vary by kit and lab—always check the laboratory’s reference ranges and correlate with clinical timing.

A positive NS1 antigen indicates early, active dengue infection — the test detects a dengue viral protein usually present in the first days of illness (typically within 0–5 days). It confirms recent infection but does not predict severity. Patients should seek medical evaluation, have serial blood counts (platelets, hematocrit) monitored, maintain hydration, and avoid NSAIDs; follow clinician advice for warning signs.

Costs vary widely: in India ~₹300–1,500 in private labs; in the UK it's usually free on the NHS but private testing ~£20–80; in the US private/insured costs $20–150 depending on lab/insurance. Prices depend on location, lab, turnaround time and whether bundled with other dengue tests. Contact your local lab for the exact fee.

ELISA can help confirm dengue by detecting NS1 antigen or dengue-specific IgM and IgG antibodies. NS1 and PCR are most useful in the first one to five days of illness; IgM appears after about four to five days and indicates recent infection. Demonstrating rising IgG or seroconversion confirms diagnosis. Cross‑reactivity with other flaviviruses and timing can affect accuracy, so clinical correlation and repeat testing may be needed.

ELISA test costs vary by country and purpose. In India typical patient charges are roughly ₹300–1,500 per test; in the US private lab prices usually range from about $10–$200. Research ELISA kits cost more (hundreds per kit but lower per-sample). In the UK routine ELISA testing is usually covered by the NHS, while private testing incurs separate fees.