External Quality Assessment for Zika Virus Molecular Diagnostic Testing, Brazil

Abstract

We conducted an external quality assessment of Zika virus molecular diagnostic tests in Brazil using a new Zika virus standard. Of 15 laboratories, 73% showed limited sensitivity and specificity. Viral load estimates varied significantly. Continuous quality assurance is required for adequate estimates of Zika virus–associated disease and determination of patient care.

External Quality Assessment for Zika Virus Molecular Diagnostic Testing, Brazil

“…To the Editor: Fischer et al described an external quality assessment exercise for laboratories in Brazil that perform molecular testing for Zika virus and the development of an armored RNA control material ( 1 ). Armored RNAs are RNA transcripts synthesized by in vitro transcription; they are encapsulated in a bacteriophage protein coat and are nuclease resistant.…”

The difficulties in obtaining reliable Zika virus diagnostics

“…73% of Brazilian laboratories presented with reduced sensitivity and specificity in detection of Zika virus genetic material. 2 The overall risk of false-negative results was 16•7% (95% CI 5•4-28•0), and the overall risk of false-positive results was 26•7% (5•0-48•5). The high risk of incorrect test results is alarming, but not restricted to resource-limited HIV epidemic in Kot Imrana is unprecedented, having expanded from a prevalence of 1•29% to one of 13•38% in just 6 months.…”

“…1 This decade, the number of travellers exporting yellow fever virus to non-endemic countries is at a record high. 2 Furthermore, in 2016, for the first time in documented history, confirmed yellow fever virus was exported in travellers from Africa to Asia, where about 2 billion immunologically naive people live in areas inhabited by the Aedes aegypti mosquito vector and are at risk for transmission. 3 The casefatality rate of yellow fever is among the highest of all arboviral diseases, underscoring the threat of a newly emerging epidemic disease problem in Asia.…”

“…Unreliable Zika virus diagnostics have a huge effect on individual and public health, potentially including illegal abortions based on false-positive test results, 4 unwarranted delays of pregnancy, and biased estimates of the absolute risk of congenital disease upon maternal infection during pregnancy. 2 The article we published on our study 2 attracted broad attention. After our paper went to press in May, 2018, the largest Brazilian newspaper, Folha de São Paulo, reported on our results.…”

“…Access of laboratories in affected regions to state-of-the-art reagents and external quality control is an unresolved key component of outbreak response. 2 Thus, national and supranational stakeholders must support public laboratories in outbreak regions that commonly deal with a huge burden of testing in the absence of adequate reagent supply.…”