To date, a high degree of polymorphism has been demonstrated at both the MSP1 and MSP2 loci in parasites from areas
of stable malaria transmission. As a consequence, in such areas it is rare to find parasites of the same 2-locus genotype
in more than 1 subject. We have studied MSP1 and MSP2 diversity in parasites collected from subjects with both
symptomatic (n = 86) and asymptomatic (34) malaria living on the island of Santo, Vanuatu, an area of stable malaria
transmission. Polymorphism at the MSP1 and MSP2 loci was considerably less than previously reported: only 5 MSP1
and 5 MSP2 alleles were detected and these showed no size variation within alleles. Santo is unique amongst the areas
studied so far in that it is a small island at the limit of the malaria belt in the South Pacific. Thus, the evolution of the
parasite population may have been affected by the small size and isolation of this island population. Moreover, limited
parasite diversity may explain the unusually mild nature of Plasmodium falciparum disease on Santo. Islands have
fascinated biologists for centuries and fuelled the advancement of evolutionary theory, since they are natural laboratories
for the study of evolution. The simplicity of the Vanuatu P. falciparum population may facilitate the use and interpretation
of sequence level analyses to address the mechanisms by which genetic diversity is generated and maintained in natural
populations.