title: [Genotyping of the Plasmodium falciparum msp1 (block 2) and dhfr (codon 108) genes in field samples collected in four endemic Colombian localities].
abstract: BACKGROUND
  Plasmodium falciparum is a highly polymorphic parasite, which allows it to evade the host's immune response, spread drug resistance and favours transmission.
  
  
  OBJECTIVE
  To analyse the genetic diversity of P. falciparum populations in samples from four endemic localities in Colombia.
  
  
  METHODS
  123 blood samples were collected on filter paper from patients with non-complicated P. falciparum malaria during 2002 to 2004. The samples were genotyped using polymerase chain reaction with specific primers for the polymorphic region of block 2 of the msp1 gene and the 108 codon of the dhfr gene.
  
  
  RESULTS
  In msp1 block 2, 95.9% (118/123; 95% CI: 90.8-98.7) of the samples harboured MAD20; 6.5% K1 (8/123; 95% CI: 2.8-12.4) and 2.4% RO33 (3/123; 95% CI: 0.5-6.9). For the dhfrgene the mutant allele N 108 was found in all the samples amplified, T 108 in 3.2% and the wild type S108 in 34.1%. Taking together all the results from both genes, 61.8% (76/123; 95% CI: 52.6-70.4) of the samples were simple infections and 38.2% (47/123; 95% CI: 29.6-47.4) were mixed infections. MAD20/N108-S108 (30.1%) was the most frequent combination among the latter.
  
  
  CONCLUSIONS
  Simple infections, i.e, a single allelic type in each one of the genes studied, prevailed among the circulating parasite populations. In this study the genetic composition of P. falciparum parasite populations was very homogeneous.
authors.affiliation: Laboratorio de Bioquímica y Biología Celular, Instituto Nacional de Salud, Bogotá, D.C., Colombia. aguerra@ins.gov.co
authors.forename: Angela Patricia
authors.initials: AP
authors.lastname: Guerra
authors.forename: Angélica
authors.initials: A
authors.lastname: Knudson
authors.forename: Rubén Santiago
authors.initials: RS
authors.lastname: Nicholls
authors.forename: John Alexander
authors.initials: JA
authors.lastname: Galindo
authors.forename: Zaava
authors.initials: Z
authors.lastname: Ravid
authors.forename: Sonia
authors.initials: S
authors.lastname: Rahirant
authors.forename: Nidia
authors.initials: N
authors.lastname: Duarte
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Chaparro-Olaya
authors.forename: Moisés
authors.initials: M
authors.lastname: Wasserman
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000627:therapeutic use; D003105:Colombia; D018562:Disease Transmission, Infectious; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy; D020066:Merozoite Surface Protein 1 / Q000235:genetics*; D010963:Plasmodium falciparum / Q000235:genetics / Q000378:metabolism; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*
chemical_list: D000962:Antimalarials; D020066:Merozoite Surface Protein 1; D013762:Tetrahydrofolate Dehydrogenase