Diagnostics in Patients At Risk for Both Dengue and Zika Infection

The United States Centers for Disease Control and Prevention (CDC) has summarized present and updated guidelines on dengue and Zika virus diagnostic testing in patients with a clinically compatible illness who live in or recently traveled to an area in which there is risk for infection with both viruses in the Morbidity and Mortality Weekly Report.

Zika virus and dengue are closely-related mosquito-borne flaviviruses that share similar transmission cycles, geographic distributions, and disease manifestations. In patients suspected of having either virus, nucleic acid amplification tests (NAATs) are the recommended diagnostic approach. Although IgM antibody testing can be used to identify additional infections and remains an important tool, interpreting antibody test results is complicated as a result of cross-reactivity and because timing of infections is difficult to pinpoint. This is especially a concern in determining whether Zika infections in pregnant women occurred during or before pregnancy.

The recommendations for screening asymptomatic pregnant women with possible exposure to Zika are unchanged. For pregnant women experiencing symptoms, serum and urine samples should be collected for concurrent NAAT and IgM testing as soon as possible for dengue testing, and within 12 weeks of symptom onset for Zika testing. In symptomatic non-pregnant individuals, NAATs for dengue and Zika are recommended using serum collected ≤7 days after the onset of symptoms. IgM antibody tests for both viruses should be done on NAAT-negative serum samples or serum collected >7 days after symptom onset. Test results positive for IgM but NAAT-negative are recommended to be retested and confirmation by neutralizing antibody test when clinically or epidemiologically indicated, including in all pregnant women. The report also recommends that when deciding which tests to perform and interpreting the results, data on the epidemiology of viruses known to be circulating at the exposure site and clinical findings should be considered.

According to the report, patients with clinically suspected dengue should be appropriately managed to monitor and treat shock and hemorrhage. In women with laboratory evidence of possible Zika infection during pregnancy, both mothers and their infants require evaluation and management of possible adverse outcomes. The report also reminds physicians that both dengue and Zika virus infections are nationally notifiable conditions and cases should be reported to public health authorities.

Reference

Sharp TM, Fischer M, Muñoz-Jordán JL, et al. Dengue and Zika virus diagnostic testing for patients with a clinically compatible illness and risk for infection with both viruses. MMWR Recomm Rep. 2019;68:1-10.