We examined geographically distinct isolates of Plasmodium vivax and catego
rized them according to developmental success in Anopheles albimanus. We fo
und that parasites from Central America and Colombia form a group distinct
from those of Asia. New World isolates have a distinct chromosomal transloc
ation and an episomal variation in the open reading frame (ORF) 470 DNA seq
uence that distinguishes them from the other isolates tested. Old World typ
es of P. vivax were introduced into the Americas, and a remnant of this lin
eage remains in P. simium. it is indistinguishable from Old World P. vivax
to the extent determinable by using our encoded markers and the examination
of its developmental pattern in mosquitoes. The cohesive characteristics t
hat separate types of P. vivax are predictors of range and potential for tr
ansmission and hence require taxonomic distinction.