Multilocus genotyping reveals high heterogeneity and strong local population structure of the Plasmodium vivax population in the Peruvian Amazon.
BACKGROUND
Peru is one of the Latin American countries with the highest malaria burden, mainly due to Plasmodium vivax infections. However, little is known about P. vivax transmission dynamics in the Peruvian Amazon, where most malaria cases occur. The genetic diversity and population structure of P. vivax isolates collected in different communities around Iquitos city, the capital of the Peruvian Amazon, was determined.


METHODS
Plasmodium vivax population structure was determined by multilocus genotyping with 16 microsatellites on 159 P. vivax infected blood samples (mono-infections) collected in four sites around Iquitos city. The population characteristics were assessed only in samples with monoclonal infections (n = 94), and the genetic diversity was determined by calculating the expected heterozygosity and allelic richness. Both linkage disequilibrium and the genetic differentiation (theta) were estimated.


RESULTS
The proportion of polyclonal infections varied substantially by site (11% - 70%), with the expected heterozygosity ranging between 0.44 and 0.69; no haplotypes were shared between the different populations. Linkage disequilibrium was present in all populations (IAS 0.14 - 0.61) but was higher in those with fewer polyclonal infections, suggesting inbreeding and a clonal population structure. Strong population differentiation (theta = 0.45) was found and the Bayesian inference cluster analysis identified six clusters based on distinctive allele frequencies.


CONCLUSIONS
The P. vivax populations circulating in the Peruvian Amazon basin are genetically diverse, strongly differentiated and they have a low effective recombination rate. These results are in line with the low and clustered pattern of malaria transmission observed in the region around Iquitos city.
Van den Eede
Peter
P
Department of Parasitology, Institute of Tropical Medicine, Antwerp, Belgium. pvandeneede@itg.be
Van der Auwera
Gert
G
Delgado
Christopher
C
Huyse
Tine
T
Soto-Calle
Veronica E
VE
Gamboa
Dionicia
D
Grande
Tanilu
T
Rodriguez
Hugo
H
Llanos
Alejandro
A
Anné
Jozef
J
Erhart
Annette
A
D'Alessandro
Umberto
U
D016054:DNA, Protozoan / Q000235:genetics*; D005787:Gene Frequency; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium / Q000235:genetics; D016780:Malaria, Vivax / Q000453:epidemiology / Q000469:parasitology* / Q000635:transmission; D018895:Microsatellite Repeats / Q000235:genetics*; D010568:Peru / Q000453:epidemiology; D010966:Plasmodium vivax / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D011995:Recombination, Genetic; D012189:Retrospective Studies
D016054:DNA, Protozoan