Key points
- NS1 antigen testing is recommended to identify dengue virus infections during the first 7 days of illness.
- A positive NS1 antigen test result confirms dengue virus infection without providing serotype information.
- The NS1 ELISA test is the only antigen test approved for diagnostic use by the FDA. The performance of other antigen tests has not been validated by CDC.
What the test is
- NS1 antigen tests detect the non-structural protein 1 (NS1) of dengue virus.
- This protein is secreted into the blood during a dengue infection.
- Most of these tests use synthetically labeled antibodies to detect dengue NS1 protein.
How NS1 antigen tests should be used and at what time during infection
Overview
- NS1 is detectable during the acute phase of dengue virus infections.
- NS1 antigen tests can be as sensitive as molecular tests during the 7 days of symptoms.
- NS1 can be detected in some people for several days after symptoms resolve.
Additional considerations
- A positive NS1 antigen test result is indicative of a dengue virus infection but does not provide serotype information. Knowing the serotype of the infecting virus is not necessary for patient care.
- However, if serotype information is needed for surveillance purposes, the sample should be tested by nucleic acid amplification tests (NAAT) (e.g., RT-PCR).
- In combination, NS1 antigen and IgM ELISA antibody tests can usually provide a diagnostic result during the first 7 days of illness.
- If results of both tests are negative, a second, convalescent specimen can be tested for IgM to help confirm or rule out infection.
Specimen type
- Serum is preferred for the NS1 ELISA test. Commercial products may accept additional specimen types like whole blood or plasma. Please refer to product specifications for more information.
Interpretation of results
- A positive NS1 antigen test result is indicative of a dengue virus infection.
- A negative NS1 antigen test result does not rule out infection.
- Patients with a negative NS1 antibody test and negative or unavailable NAAT test should be tested for the presence of dengue IgM antibodies to determine possible recent dengue exposure.
Availability
Currently, the NS1 ELISA test is the only dengue antigen test approved by the U.S. Food and Drug Administration (FDA). The performance of other commercial dengue NS1 antigen and rapid diagnostic tests is not well established by CDC. These tests are labeled for Research Use Only (RUO) and are not intended for diagnostic procedures. No rapid diagnostic tests that include dengue NS1 detection have received FDA approval.