Finding the right tests…
Emergency services available 24 x 7
Emergency services available 24 x 7
Finding the right tests…
Serology
DENGUE (NS1) looks for a piece of the dengue virus itself, a protein called NS1, rather than your immune response to it. Because NS1 appears in your blood before your immune system makes antibodies, this test can catch dengue very early — often from the first day of fever — and stays useful through roughly the first week of illness. After about day 7, NS1 levels fall enough that a negative result no longer rules dengue out, and antibody testing becomes more useful instead. Your doctor typically orders this test in the first few days of a fever that looks like dengue, when antibody tests might still come back falsely negative.
NS1 antigen either shows up in your blood or it doesn't, which is what this test reports as a positive or negative result rather than a numeric value. NS1 can be detected as early as day 1 of illness and generally stays detectable through about day 9, though it's most reliable in the first week. It's usually ordered on its own only in the very early days of fever; after that window, your doctor typically adds an antibody test since NS1 alone becomes less reliable. A single blood sample is enough, with no special preparation needed.
NS1 is a protein the dengue virus makes and releases into your blood during active infection, well before your immune system has built up antibodies against it. This is what makes an NS1 test useful in the first days of illness, when an antibody test might still come back negative even in someone who genuinely has dengue.
NS1 is typically detectable within the first one to two days of infection and remains so for up to nine days after symptoms start. In someone who's had dengue before, a second infection can still be detected by NS1, but usually for a shorter stretch — around one to four days after symptoms begin — since a stronger, faster immune response clears the antigen sooner.
A positive NS1 result is a strong indicator of current dengue infection. A negative result taken after about day 7 is much less reassuring, since the antigen may already have cleared even though the illness continues — at that point, IgM and IgG antibody testing becomes the more reliable check. This is why doctors often pair NS1 with an antibody test, or order antibody testing on its own once several days have passed since symptoms began.
NS1 can be detected within the first one to two days of infection, according to CDC guidance, and remains useful through roughly the first week of illness.
A negative result after about day 7 is far less reassuring, since NS1 levels can fall even though the illness continues. Your doctor will likely rely on antibody testing instead at that point.
No. NS1 is a viral protein, so this test detects a piece of the dengue virus itself rather than your immune system's antibody response to it.
Yes, but usually for a shorter window — around one to four days after symptoms start — compared with a first infection, since a stronger immune response clears the antigen faster the second time.
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.
Often, yes. CDC guidance recommends pairing NS1 with an IgM antibody test during the first week of illness, since the two catch dengue at different points in the infection.
No. No special preparation, including fasting, is needed before this blood draw.
No. This test only shows whether dengue NS1 protein is present, not which of the four dengue virus serotypes is responsible; that needs specialised molecular testing.