Zika Test Results (IMAGE) Cell Press Caption This image shows a black cartridge containing a paper-based diagnostic for detecting the Zika virus is held up by a researcher at Harvard's Wyss Institute. Areas that have turned purple indicate samples infected with Zika, while yellow areas indicate samples that are free of the virus. Credit Wyss Institute at Harvard University Usage Restrictions Credit Required. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.