Zika virus diagnostic algorithm

Establishment of a comprehensive and high throughput serological algorithm for Zika virus diagnostic testing. Mendoza EJ*, Makowski K*, Barairo N*, Holloway K*, Dimitrova K*, Sloan A*, Vendramelli R*, Ranadheera C*, Safronetz D*, Drebot MA*, Wood H*. Diagn Microbiol Infect Dis 2019 Jun;94(2):140-6. doi: https://doi.org/10.1016/j.diagmicrobio.2019.01.004

The important work described in this publication is being implemented to improve turnaround time for Zika virus testing. As the reference laboratory for Canada, the NML plays a key role in not only conducting diagnostic testing, but also innovating and applying discovery research to address public health priorities.

What was known about this area prior to your work, and why was the research done?

During the 2015-2016 Zika virus (ZIKV) epidemic, thousands of Canadian travelers sought testing to assess the risk of having a baby with birth defects associated with ZIKV infection during pregnancy. At that time, a large proportion of samples required confirmation by the plaque reduction neutralization test (PRNT), proving to be laborious and time-consuming. The new diagnostic algorithm proposed in this study uses a combination of serological tests for preliminary screening to reduce the number of samples requiring confirmatory testing via PRNT.

What are your most significant findings from this work?

This study established anti-ZIKV IgM and IgG ELISA combinations with improved sensitivities for acute and convalescent samples over the previous serological screening protocol. The combinations demonstrated near-perfect inter-rater agreement with the gold-standard serological assay, PRNT. Future studies could identify the maximum sample collection time post-exposure/onset to ensure screening is effective. Until then, PRNT testing should be considered for samples collected after 3 months of exposure/onset from pregnant women, in their first trimester of pregnancy, who have travelled to areas with active ZIKV transmission.

What are the implications or impact of the research?

The new high throughput serological algorithm for ZIKV diagnostic testing has been implemented at the National Microbiology Laboratory. It has proven to greatly reduce the logistical limitations and turnaround times for ZIKV diagnostic testing. Furthermore, the algorithm has now been implemented by four provincial laboratories conducting ZIKV serological screening.

Additional References of Significance:

  • Lanciotti RS, Kosoy OL, Laven JJ, et al. Genetic and Serologic Properties of Zika Virus Associated with an Epidemic, Yap State, Micronesia, 2007. Emerg Infect Dis 2008 Aug;14(8) :1232–9. doi: http://doi.org/10.3201/eid1408.080287
  • Campos GS, Bandeira AC, Sardi SI. Zika Virus Outbreak, Bahia, Brazil. Emerg Infect Dis 2015 Oct;21(10):1885-6. doi: http://doi.org/10.3201/eid2110.150847

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