Key points
- Clinicians should consider dengue in patients with fever, who live in or recently traveled to areas with risk of dengue. In addition to fever, common dengue symptoms include severe headache, retro-orbital pain, myalgia and arthralgia, macular or maculopapular rash.
- For acute dengue diagnosis, clinicians should order a nucleic acid amplification test (NAAT) and an IgM antibody test or an NS1 antigen test and an IgM antibody test.
- If dengue is suspected, clinicians should provide appropriate management without waiting for diagnostic test results.
Overview
To determine if recent illness is due to infection with dengue virus, healthcare providers should review:
- Patient’s medical history
- Patient's place of residence and recent travel history
- CDC travel notices regarding disease outbreaks
- Vaccination records (particularly for dengue, yellow fever, and Japanese encephalitis)
Acute phase: 0-7 days after symptom onset
- During this period, laboratory diagnosis should be made on serum samples using either one of these test combinations:
- A nucleic acid amplification test (NAAT) (e.g., RT-PCR) and an IgM antibody test OR
- An NS1 antigen test and an IgM antibody test
- A serum sample is preferred for dengue testing.
- Dengue virus RNA can be detected with NAAT in blood, serum, and plasma. Most of these tests identify the infecting dengue virus serotype. A positive NAAT test does not require further confirmatory testing.
- The presence of the dengue virus non-structural protein 1 (NS1) in serum during the first 7 days of illness is indicative of a current or recent dengue virus infection.
- A negative result from an NAAT or NS1 antigen test does not rule out infection.
- A positive result by NAAT or NS1 antigen meets the confirmatory laboratory criteria for diagnosis in the National Notifiable Diseases Surveillance System (NNDSS) dengue case definition.
Convalescent phase: >7 days post symptom onset
- When the acute (0-7 days) sample is negative in the recommended test combinations or is not available, a convalescent serum sample can be collected and tested.
- IgM antibody testing is recommended as the primary test after day 7 of symptom onset.
- Some patients may be positive on NAAT or NS1 antigen tests after day 7 of illness.
- IgM antibodies can be detected by an IgM antibody test for approximately 3 months after infection, but its detection becomes less reliable as antibody levels decrease over time.
Interpreting test results
- Patients with a positive NAAT (e.g., RT-PCR) or NS1 antigen test have a confirmed acute dengue virus infection.
- Patients who have IgM antibodies against dengue virus in a single sample are classified as having a presumptive, recent dengue virus infection.
- Patients with a change from negative to positive IgM results in paired samples (first sample collected during the first 7 days of illness, and second sample collected after symptoms subside) are classified as recent dengue infections.
IgG testing
- Serologic testing by IgG in a single specimen is not recommended for diagnosis of acute dengue in patients, as these tests may detect antibodies from dengue infections or other flavivirus infections that occurred in the past
- Patients with a change from negative to positive IgG results in paired samples (first sample collected during the first 7 days of illness, and second sample collected after symptoms subside) are considered recent dengue infections.
Recommended tests
For symptomatic persons with dengue virus infection, dengue virus RNA can usually be detected by molecular tests for the first 0-7 days in the course of illness. After day 7, molecular tests may not be optimal.
NS1 is detectable during the acute phase of dengue virus infections. NS1 antigen tests can be as sensitive as molecular tests during the first 0-7 days of symptoms. After day 7, NS1 tests may not be optimal.
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.
IgM antibody testing can identify most recent dengue infections after day 3 of illness. These tests should be run on samples with negative NS1 antigen and PCR results, particularly after day 3 of illness. Interpreting positive IgM results is complicated because of cross-reactivity with other flaviviruses, like Zika and West Nile viruses.
Plaque Reduction Neutralization Tests (PRNT) can resolve false-positive IgM antibody results caused by non-specific reactivity, and, in some cases, can help identify the infecting virus. However, in areas with high prevalence of dengue and Zika virus neutralizing antibodies, PRNT may not confirm a significant proportion of IgM positive results.
Diagnosis
- All patients with clinically suspected dengue should receive appropriate management without waiting for diagnostic test results. Clinicians should monitor for shock and reduce the risk of complications resulting from increased vascular permeability, plasma leakage, and organ damage.
- Clinical samples can be referred to most state health departments or to commercial laboratories that offer dengue diagnostic testing.
Diagnosis in special circumstances
Cross reactivity is a limitation of dengue serological tests and is seen when antibodies against other flaviviruses react on the dengue IgM antibody test. Physicians may consult with state or local public health laboratories or CDC for guidance about when plaque reduction neutralization testing (PRNT) can help differentiate between dengue and other flaviviruses including, Zika, Japanese encephalitis, St. Louis encephalitis, West Nile, and yellow fever viruses. PRNT does not always a give conclusive diagnostic result, particularly in patients that have previously been exposed to more than one flavivirus. Current dengue molecular tests (e.g., RT-PCR) and NS1 antigen tests do not have cross-reactivity with other flaviviruses of concern.
If the patient is pregnant and symptomatic and lives in or has traveled to an area with risk of exposure to Zika virus, test for Zika using molecular tests in addition to dengue. Clinicians should review Zika testing recommendations.
Reporting cases
In the United States, all suspected cases should be reported to the state or local health department, because dengue is a nationally notifiable disease.
- CDC can provide confirmatory dengue testing on samples submitted by state laboratories.
- CDC will report results to the submitting public health laboratory.
Resources
- Hunsperger EA, Munoz-Jordan J, Beltran M, Colon C, Carrion J, Vazquez J, Acosta LN, Medina-Izquierdo JF, Horiuchi K, Biggerstaff BJ, Margolis HS. Performance of dengue diagnostic tests in a single-specimen diagnostic algorithm. J Infect Dis. 2017 Sept 15;214(7):837-44.
- Santiago GA, Verge E, Quiles Y, Cosme J, Vazquez J, Medina JF, Medina F, Colon C, Margolis H, Munoz-Jordan. Analytical and clinical performance of the CDC real time RT-PCR assay for detection and typing of dengue virus. PLoS Negl Trop Dis. 2013 July;7(7):e2311.
- Santiago GA, Vazquez J, Courtney S, Matias KY, Andersen LE, Butler AE, Roulo R, Bowzard J, Villanueva JM, Munoz-Jordan JL. Performance of the Trioplex real-time RT-PCR assay for detection of Zika, dengue, and chikungunya viruses. Nat Commun. April 2018;11;9(1):1391-1401.
- Sharp TM, Fischer M, Muñoz-Jordán JL, Paz-Bailey G, Staples JE, Gregory CJ, Waterman SH. Dengue and Zika virus diagnostic testing for patients with a clinically compatible illness and risk for infection with both viruses. MMWR. 2019 June 14;68(1):1-10.
- Waterman SH, Margolis HS, Sejvar JJ. Surveillance for dengue and dengue-associated neurologic syndromes in the United States. Am J Trop Med Hyg. 2015 May 7;92(5):997-98.