Origin of Plasmodium falciparum malaria is traced by mitochondrial DNA

The origin and geographical spread of Plasmodium falciparum is here determi ned by analysis of mitochondrial DNA sequence polymorphism and divergence f rom its most closely related species P. reichenowi (a rare parasite of chim panzees). The complete 6 kb mitochondrial genome was sequenced from the sin gle known isolate of P. reichenowi and from four different cultured isolate s of P. falciparum, and aligned with the two previously derived P. falcipar um sequences. The extremely low synonymous nucleotide polymorphism in P. fa lciparum (pi = 0.0004) contrasts with the divergence at such sites between the two species (K = 0.1201), and supports a hypothesis that P. falciparum has recently emerged from a single ancestral population. To survey the geog raphical distribution of mitochondrial haplotypes in P. falciparum, 104 iso lates from several endemic areas were typed for each of the identified sing le nucleotide polymorphisms. The haplotypes show a radiation out of Africa, with unique types in Southeast Asia and South America being related to Afr ican types by single nucleotide changes. This indicates that P. falciparum originated in Africa and colonised Southeast Asia and South America separat ely. (C) 2000 Elsevier Science B.V. All rights reserved.