[Genotyping of the Plasmodium falciparum msp1 (block 2) and dhfr (codon 108) genes in field samples collected in four endemic Colombian localities].
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.
Guerra
Angela Patricia
AP
Laboratorio de Bioquímica y Biología Celular, Instituto Nacional de Salud, Bogotá, D.C., Colombia. aguerra@ins.gov.co
Knudson
Angélica
A
Nicholls
Rubén Santiago
RS
Galindo
John Alexander
JA
Ravid
Zaava
Z
Rahirant
Sonia
S
Duarte
Nidia
N
Chaparro-Olaya
Jacqueline
J
Wasserman
Moisés
M
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*
D000962:Antimalarials; D020066:Merozoite Surface Protein 1; D013762:Tetrahydrofolate Dehydrogenase