Dengue - RNA PCR - Qualitative

The dengue RNA PCR test (RT‑PCR) detects and amplifies dengue virus RNA in a patient’s blood to confirm acute infection. It is most useful in early illness—typically the first 1–7 days—before antibodies develop. The assay is highly sensitive and specific, can identify dengue serotype, requires a diagnostic laboratory, and supports clinical management and outbreak surveillance.

A qualitative dengue test is typically a rapid immunoassay that gives a positive/negative result for dengue NS1 antigen and/or dengue-specific IgM and IgG antibodies. NS1 is usually detectable during the first week of fever, while IgM appears after about 4–5 days (indicating recent infection) and IgG indicates prior exposure. Positive results guide management and may prompt confirmatory testing.

A positive dengue PCR means dengue virus RNA was detected in the blood, confirming an active, acute infection—usually during the first 5 to 7 days of illness. It indicates ongoing viral replication and can identify the serotype. Clinical assessment and monitoring for dehydration, bleeding, or warning signs are needed. PCR doesn’t indicate past immunity; negative results later don’t exclude dengue.

Cost varies widely by country and provider. In India private labs typically charge around ₹2,000–6,000; in the US private lab fees often fall between $100–$400; in the UK NHS testing is usually free but private testing costs about £80–£200. Prices depend on lab, test type, urgency, and whether insurance or public health covers it—check local laboratories or hospitals for exact fees.

Dengue virus RNA is detectable by RT‑PCR during the early (acute) phase, typically within the first 1–7 days of fever. A positive RNA test confirms current dengue infection. After the acute period viral RNA declines and may be undetectable, so a negative result late in illness doesn’t exclude dengue — serologic testing for IgM/IgG is then useful.

Dengue is confirmed by direct detection of the virus or its components: RT‑PCR (viral RNA) or NS1 antigen test during the first 5–7 days of illness. After about day 5, serology (dengue IgM, with IgG indicating past exposure) is used; a rising IgM/IgG titre or paired acute and convalescent samples confirms recent infection. Platelet counts and clinical features support diagnosis.