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Class of Test Specific Type of Test Estimated Sensitivity Estimated Specificity Risk of Cross-Reactivity Timing Molecular: identify Zika RNA Polymerase chain reaction; transcription-mediated amplification Incompletely characterized; tests currently authorized for US use have labeled limits of detection across three orders of magnitude. So, while some are extremely sensitive, the least sensitive tests would have failed to detect more than half of positive cases in a recent, large Nicaraguan cohort. Incompletely characterized but expected to be high. Expected to be rare. Only positive while the person is viremic. Window period is normally short, but will cease positive results within a few weeks after symptoms resolve. Mild and nonspecific symptoms for many patients complicate correct timing. Serologic: identify antibody against Zika Enzyme-linked immunosorbent assay 37% to 100% in various studies. 66% to 100% in various studies. Risk of false positives calls for confirmation by plaque reduction neutralization test under certain situations in CDC algorithm. 8% to 40% in various studies, which would reduce effective specificity when cross-reacting viruses are likely present. Most tests identify IgM, which usually develops within a few days after symptoms and decline after about three months (though it sometimes be detected for over a year). A few tests identify IgG, which develops later, although as early as 10 days after symptoms in some cases, but persists for years. CDC, Centers for Disease Control and Prevention.
Criteria for testing Pregnant women who
traveled while pregnant to an area with Zika virus transmission OR
had unprotected sex (vaginal, anal, or oral) with a partner who spent time in an area with Zika virus transmission
Persons who develop/developed compatible symptoms during or within 4 weeks of travel to an area with Zika virus transmission
Neonates with suspected or confirmed microcephaly or intercranial calcifications born to women who
traveled while pregnant to an area with Zika virus transmission OR
had unprotected sex (vaginal, anal, or oral) with a partner who spent time in an area with Zika virus transmission
Anyone who developed Guillain-Barré syndrome after spending time in an area with active Zika virus transmission
Other special conditions with epidemiological linkage to a confirmed or probably case of Zika virus infection including
recipient of blood, blood products, or organ transplant OR
suspected transfusion-associated transmission, OR
suspected mosquito-borne transmission, OR
any other unusual clinical manifestation or suspected route of exposure
Laboratory testing, if indicated, can be performed at DOHMH or at a specified commercial laboratory. Patient specimens from travel-associated cases of suspected Zika virus infection are sent to the commercial laboratory for testing and do not require the clinician to call DOHMH. Clinicians are instructed to call DOHMH for testing in all nontravel-associated cases of suspected Zika virus disease. DOHMH, Department of Health and Mental Hygiene.
