Short report: Rosette formation in Plasmodium ovale infection.

Red blood cells infected by mature stages of Plasmodium ovale obtained from a 56-year-old Thai patient formed rosettes readily with uninfected erythrocytes. Ex vivo, the ring stage-infected erythrocytes matured well under the in vitro conditions used for P. falciparum culture, and the infected erythrocytes formed rosettes when the parasites became mature trophozoites. These rosettes were stable and remained intact until completion of schizogony. Plasmodium ovale rosettes were similar to those formed by P. falciparum- and P. vivax-infected erythrocytes. Rosette formation appears to be a common property of three species of human plasmodia.