The PCR test for dengue detects dengue virus RNA in a patient's blood to confirm acute infection. It is most useful during the early febrile phase (typically the first 5–7 days), offers high sensitivity and can identify the specific dengue serotype. Testing requires specialized laboratory equipment and becomes less helpful once antibodies develop later in illness.

PCR is generally better for early dengue detection and confirmation: it detects viral RNA with higher sensitivity and specificity in the first 5–7 days and can identify serotype. NS1 antigen testing is useful as a rapid point-of-care test early in illness but is less sensitive in secondary infections and later stages. PCR requires specialized labs and is costlier.

The cost of a dengue PCR test varies widely by country and lab. In India it commonly ranges about ₹1,500–₹5,000 (≈ $20–$65). In private laboratories in other countries it typically costs roughly $50–$300; public or referral labs may offer free or subsidised testing. Final price depends on location, test platform, urgency, and whether insurance or government programs cover it.

Three main tests diagnose dengue: NS1 antigen test (detects viral protein early, usually first ~1–5 days), RT‑PCR (detects dengue RNA, useful in the acute phase), and serology for dengue-specific antibodies (IgM indicates recent infection from about day 4–5; IgG suggests past or secondary infection). Clinicians choose tests by illness day and clinical context.

Dengue PCR is usually positive during the acute viremic phase, typically from day 1 of fever up to about day 5–7. Sensitivity declines sharply after the first week of illness, so PCR is most useful within the first 4–7 days. After this period, antibody tests (IgM/IgG) are generally preferred, although rare cases may show detectable RNA slightly longer.

PCR (polymerase chain reaction) testing detects a pathogen’s genetic material by copying and amplifying DNA or RNA (via reverse transcription for RNA viruses). A sample (e.g., nasal swab or saliva) is processed to reveal tiny amounts of target sequences. PCR is highly sensitive and specific, widely used for diagnosing infections like COVID‑19; a positive result shows genetic material was present, not necessarily active infectiousness.