Rhesus macaques with clinically undetectable Plasmodium relapse infections still harbor parasitic gametocytes that may be infectious to mosquitoes, according to a study published September 19 in PLOS Pathogens by F. Eun-Hyung Lee and Mary R. Galinski of Emory University, Tracey J. Lamb of the University of Utah, and colleagues. The study has important epidemiological implications relevant to malaria elimination strategies.