<i>P. vivax</i> Invasion Up Close (IMAGE) Case Western Reserve University Caption Plasmodium vivax has traditionally infected red blood cells of hosts in the Duffy positive blood group but Duffy negative people have been resistant. Credit Samantha Zimmerman Usage Restrictions Credit Samantha Zimmerman 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.