Table 3. Diagnostic test interpretations among participants with PCR-confirmed Zika virus disease in Miami–Dade County, Florida, USA, based on IgM and neutralizing antibody results 12–19 months after onset*.
| Test results | No. (%), n = 62 | Interpretation† |
|---|---|---|
| Zika virus IgM positive or equivocal, n = 57 | ||
| Zika virus PRNT titer >10 and DENV PRNT titer <10 | 21 (34) | Recent Zika virus infection |
| Zika virus PRNT titer >4-fold higher than DENV PRNT titer | 21 (34) | Recent flavivirus infection |
| <4-fold difference between Zika virus and DENV PRNT titers | 11 (18) | Recent flavivirus infection |
| DENV PRNT titer >4-fold higher than Zika virus PRNT titer |
4 (6) |
Recent flavivirus infection |
| ZIKV IgM negative, n = 5 | ||
| Zika virus PRNT titer >10 and Zika virus PRNT titer <10 | 2 (3) | Previous Zika virus infection |
| Zika virus PRNT titer >4-fold higher than DENV PRNT titer | 1 (2) | Previous flavivirus infection |
| <4-fold difference between Zika virus and DENV PRNT titers | 1 (2) | Previous flavivirus infection |
| DENV PRNT titer >4-fold higher than Zika virus PRNT titer | 1 (2) | Previous flavivirus infection |
*DENV, dengue virus; PRNT, plaque reduction neutralization test. †Recent Zika virus infection: Zika virus IgM positive or equivocal with a Zika virus PRNT titer ≥10 and dengue PRNT titer <10; recent flavivirus infection: Zika virus IgM positive or equivocal with a Zika virus PRNT titer >10 or dengue PRNT titer >10; previous Zika virus infection: Zika virus IgM negative with a Zika virus PRNT titer ≥10 and dengue PRNT titer <10; previous flavivirus infection: Zika virus IgM negative with a Zika virus PRNT titer >10 or dengue PRNT titer >10.