title: Recurrent parasitemias and population dynamics of Plasmodium vivax polymorphisms in rural Amazonia.
abstract: Clinical trials documented alarming post-treatment Plasmodium vivax recurrence rates caused by recrudescence of surviving asexual blood stages, relapse from hypnozoites, or new infections. Here we describe high rates of P. vivax recurrence (26-40% 180 days after treatment) in two cohorts of rural Amazonians exposed to low levels of malaria transmission after a vivax malaria episode treated with chloroquine-primaquine. Microsatellite analysis of 28 paired acute infection and recurrence parasites showed only two pairs of identical haplotypes (consistent with recrudescences or reactivation of homologous hypnozoites) and four pairs of related haplotypes (sharing alleles at 11-13 of 14 microsatellites analyzed). Local isolates of P. vivax were extraordinarily diverse and rarely shared the same haplotype, indicating that frequent recurrences did not favor the persistence or reappearance of clonal lineages of parasites in the population. This fast haplotype replacement rate may represent the typical population dynamics of neutral polymorphisms in parasites from low-endemicity areas.
authors.affiliation: Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil. pamelaorjuela@gmail.com
authors.forename: Pamela
authors.initials: P
authors.lastname: Orjuela-Sánchez
authors.forename: Natal Santos
authors.initials: NS
authors.lastname: da Silva
authors.forename: Mônica
authors.initials: M
authors.lastname: da Silva-Nunes
authors.forename: Marcelo Urbano
authors.initials: MU
authors.lastname: Ferreira
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000627:therapeutic use; D001938:Brazil / Q000453:epidemiology; D002738:Chloroquine / Q000627:therapeutic use; D004351:Drug Resistance; D006239:Haplotypes; D006801:Humans; D016780:Malaria, Vivax / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology*; D018895:Microsatellite Repeats / Q000235:genetics; D018512:Parasitemia / Q000469:parasitology*; D010966:Plasmodium vivax / Q000235:genetics*; D011319:Primaquine / Q000627:therapeutic use; D012008:Recurrence; D012424:Rural Population; D013997:Time Factors
chemical_list: D000962:Antimalarials; D002738:Chloroquine; D011319:Primaquine