Finding the right tests…
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Emergency services available 24 x 7
Finding the right tests…
Molecular
RT-PCR for dengue looks directly for the virus's genetic material in a blood sample, rather than for antibodies your immune system makes in response to it. That makes it most useful early in the illness, typically within the first five to seven days after fever starts, before antibody-based tests become reliable. Unlike an NS1 antigen test, which detects a viral protein, RT-PCR can also identify which of the four dengue serotypes is causing the infection, information that matters because a second infection with a different serotype later in life carries a higher risk of severe dengue. Doctors treat based on symptoms and don't wait for this result before starting supportive care.
A positive RT-PCR confirms active dengue infection and identifies the viral serotype involved. A negative result taken within the first week makes dengue less likely but doesn't rule it out completely, especially if the sample was collected right at the edge of that window; your doctor may add an NS1 antigen or IgM antibody test to cover the gap. Beyond about a week after symptoms start, RNA levels drop enough that a negative RT-PCR becomes far less informative, and antibody testing takes over as the more reliable option.
Dengue can be diagnosed a few different ways: an antibody test (IgM/IgG), a test for a viral protein called NS1, or RT-PCR, which detects the virus's own RNA. RT-PCR is the only one of the three that can tell your doctor which of the four dengue serotypes you're infected with, which matters because a second infection with a different serotype is linked to a higher chance of severe dengue than a first infection carries.
Dengue virus is present in the blood for roughly the first four to five days of illness, and CDC guidance recommends RT-PCR or another molecular test during the first week after symptoms start. IgM antibodies, by contrast, take days to build up: detectable in only about half of patients by day 3 to 5 of illness, rising in the large majority by day 10. That's the opposite pattern from RT-PCR, most sensitive early and least useful later, once the virus has largely cleared from the bloodstream.
Because RT-PCR's usefulness narrows quickly after the first week, a negative result taken late in the illness carries much less weight than one taken on day two or three. Doctors treat suspected dengue based on symptoms and don't hold off on supportive care while waiting on lab results, since early management matters more than confirming the exact diagnosis immediately.
NS1 detects a viral protein and performs comparably to RT-PCR in the first week of illness, but only RT-PCR identifies which of the four dengue serotypes is involved. Your doctor may order either, or both, depending on how many days into the illness you are.
RT-PCR detects the virus's genetic material directly and works best early in the illness, while IgM detects your immune system's response and becomes more reliable after day 3, once antibody levels have had time to rise. The two tests are most useful at different points in the same illness.
RT-PCR is most useful within the first five to seven days after fever begins, while the virus is still present in the blood in detectable amounts. Testing much later in the illness reduces how much it can tell you.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
It makes dengue less likely, especially if the sample was taken early in the illness, but it doesn't rule dengue out completely, particularly if testing happened later than a week after symptoms began. Your doctor may add an NS1 or IgM test to cover that gap.
A second dengue infection with a different serotype than your first is linked to a higher risk of severe dengue than a first infection generally carries. Knowing the serotype can matter for your doctor's monitoring, especially if you've had dengue before.
This test doesn't typically require fasting, but ask your doctor or the centre about any preparation specific to your situation before your visit.