Typical morphology of erythrocytic stages of B. microti in patients in the area along the China-Myanmar border in the Yunnan province, P.R. China. Giemsa-stained thin blood films from field samples. A: Early trophozoite or ring form of P. falciparum and malaria pigment was scattered in the infected erythrocytes. B: Ring forms of B. microti in one erythrocyte without pigment. C: Two ring forms take residents in one erythrocyte D: Tetrads of merozoites that are arranged in a cross-like pattern (a so-called Maltese cross).