Testing of specimens within the United States to determine possible Zika virus infection should be limited to specimens collected from patients meeting CDC’s clinical and epidemiological criteria for testing. As previously indicated, information on clinical signs and symptoms associated with Zika virus infection is available from the CDC. It is important to note that Zika virus infection can cause signs and symptoms similar to those seen in patients with dengue and chikungunya virus infections. In addition, the primary diagnostic specimens recommended by the CDC for Zika virus infection are serum and urine.
Complete testing algorithms for symptomatic individuals and asymptomatic pregnant women are available from the CDC. The images are reproductions of the testing algorithms for symptomatic individuals with specimens collected <14 days after symptoms (on the right) and symptomatic individuals with specimens collected >14 days after symptoms (below).
The following are summaries of the testing algorithms for symptomatic individuals meeting epidemiological criteria:
- Serum and urine collected from symptomatic patients <14 days post onset of symptoms should be tested by the Zika virus rRT-PCR method.
- A positive Zika virus rRT-PCR result in either specimen is sufficient to diagnose Zika virus infection. If Zika virus rRT-PCR results are negative for both specimens, serum should be tested by antibody detection methods (Zika MAC-ELISA).
- If serum results for Zika MAC-ELISA are positive or equivocal, then the serum must be confirmed by PRNT assay. If Zika MAC-ELISA is negative, then no further testing is required.
- Serum that has been collected from patients presenting 2-12 weeks from onset of symptoms should be tested first by Zika MAC-ELISA method, If the Zika MAC-ELISA test is positive or equivocal and patient is non-pregnant, then the PRNT test should be performed. If patient is pregnant, then rRT-PCR for Zika should be performed.
