Since the Kachin ethnic group also resides in vivax-malaria endemic areas and many of the participants with the G6PD Mahidol mutation were predicted to have <10% residual enzyme activity based on the complete absence of fluorescence by the FST, the standard 14 day primaquine treatment of vivax malaria needs to be administrated with great caution. This evidence concerns the gene G6PD and Plasmodium vivax malaria.