title: A molecular surveillance system for global patterns of drug resistance in imported malaria.
abstract: Analysis of imported malaria in travelers may represent a novel surveillance system for drug-resistant malaria. We analyzed consecutive falciparum malaria isolates from Canadian travelers from 1994 to 2000, for polymorphisms in pfcrt, dhfr, and dhps linked to chloroquine and pyrimethamine/sulfadoxine resistance. Forty percent of isolates possessed the K76 pfcrt allele, suggesting that many imported falciparum infections are still responsive to chloroquine. Travelers who had recently taken chloroquine had a significantly increased risk of harboring isolates with pfcrt resistance alleles (odds ratio = 4.47; p=0.03). The presence of two or more mutations in dhfr or dhps was found in 64.8% (95% confidence interval [CI] 54.6 to 73.9) and in 30.4% (95% CI 21.7 to 40.3) of isolates, respectively, and increased significantly over the course of the study. These molecular markers indicate that pyrimethamine/sulfadoxine resistance is increasing and is now too high to rely on this drug as a routine therapeutic agent to treat malaria in travelers.
authors.affiliation: Toronto General Hospital, University of Toronto, Canada.
authors.forename: Annie-Claude
authors.initials: AC
authors.lastname: Labbé
authors.forename: Samir
authors.initials: S
authors.lastname: Patel
authors.forename: Ian
authors.initials: I
authors.lastname: Crandall
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Kain
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D002738:Chloroquine / Q000494:pharmacology; D004351:Drug Resistance / Q000235:genetics*; D005260:Female; D005819:Genetic Markers; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000469:parasitology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics; D011159:Population Surveillance; D015800:Protozoan Proteins / Q000235:genetics; D011739:Pyrimethamine / Q000494:pharmacology; D013413:Sulfadoxine / Q000494:pharmacology; D014195:Travel
chemical_list: D000962:Antimalarials; D005819:Genetic Markers; D015800:Protozoan Proteins; D013413:Sulfadoxine; D002738:Chloroquine; D011739:Pyrimethamine