Linearized, circular neighbour-joining tree showing the relationships between multilocus microsatellite haplotypes derived from 55 Plasmodium falciparum isolates from Acre, Brazil. The genetic distance between pairs of haplotypes was estimated as 1 – the proportion of shared alleles. Different symbols at the branch tips show the date of collection of the parasites: 2004, black circles; 2005, white circles; 2006, white squares; and 2008, black squares. Terminal branches of zero length indicate parasites with identical multilocus haplotypes. The most common haplotype was shared by 9 isolates collected in Granada in 2004 and 2006 and by 1 isolate collected in Plácido de Castro in 2008.