No abstract

Zika virus (ZIKV) emerged and spread rapidly in South American countries during 2015. Efforts to diagnose ZIKV infection using serological tools were challenging in dengue-endemic areas because of antigenic similarities between both viruses. Here, we assessed the performance of an in-house developed IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) and the plaque reduction neutralization test (PRNT) to diagnose ZIKV infection. Acute and convalescent paired serum samples from 51 patients who presented with clinical symptoms suggestive of an arbovirus illness in dengue-endemic areas of Honduras, Venezuela, Colombia and Peru were used in the assessment. Samples were tested for ZIKV, dengue and chikungunya virus using a variety of laboratory techniques. The results for the ZIKV-RNA screening and seroconversion detected by the microneutralization test were used to construct a composite reference standard. The overall sensitivity and specificity for the MAC-ELISA were 93.5% and 100.0%, respectively. Contrastingly, the overall sensitivity and specificity for the PRNT were 96.8% and 95.0%, respectively. Restricting the analysis according to IgM or neutralizing antibodies against dengue, the performances of both serological assays were adequate. The findings of this study reveal that the MAC-ELISA and PRNT would provide initial reliable laboratory diagnostic assays for ZIKV infection in dengue-endemic areas.

The isolation of Zika virus (ZIKV) from serum of suspected human cases for diagnostic purposes can be challenging due to infrastructure constraints of laboratory testing technology. Therefore, as an alternative method, the objective of this study was to evaluate a random sample of oropharyngeal swabs for the diagnosis of ZIKV infection among patients with symptoms of arboviral and respiratory illness. The results revealed that ZIKV RNA could be detected by a reverse transcriptase polymerase chain reaction (RT-PCR) assay and isolated from oropharyngeal swabs from five of 38 samples, but serum samples from the same patients were negative for ZIKV by a variety of laboratory diagnostic approaches including RT-PCR and viral isolation followed by immunofluorescence assays. The findings suggested that the molecular detection and isolation of ZIKV in oropharyngeal swab warrants further study for consideration as an improved diagnostic procedure.