We conducted surveillance for multidrug-resistant Plasmodium falciparum in Cambodia during 2004-2006 by assessing molecular changes in pfmdr1. The high prevalence of isolates with multiple pfmdr1 copies found in western Cambodia near the Thai border, where artesunate-mefloquine therapy failures occur, contrasts with isolates from eastern Cambodia, where this combination therapy remains highly e...

Malaria control is compromised by the development and spread of Plasmodium falciparum resistance to antimalarial drugs, which has caused an increase in malaria related morbidity and mortality. Artemisinin based combination therapy (ACT) has been implemented in almost all malaria endemic areas in an attempt to suppress drug resistance. The ACT artemether-lumefantrine (Coartem®; Novartis) is one ...

Surveillance for Plasmodium falciparum drug resistance mutations is becoming an established tool for assessing antimalarial treatment effectiveness. We used an extended version of a high-throughput post-PCR multiplexed ligase detection reaction fluorescent microsphere assay (LDR-FMA) to detect single-nucleotide P. falciparum drug resistance polymorphisms in 402 isolates from children in Papua N...

On the western border of Thailand, Plasmodium falciparum has become resistant to almost all antimalarial agents. The molecular basis of resistance in these parasite populations has not been well characterized. This study assessed genetic polymorphisms in the pfmdr1 gene in 54 parasites collected from the western border of Thailand to determine the relationship of pfmdr1 copy number and codon mu...

Single Nucleotide Polymorphisms (SNPs) in the Pfmdr1, and Pfcrt, genes of Plasmodium falciparum may confer resistance to a number of anti-malaria drugs. Pfmdr1 86Y and haplotypes at Pfcrt 72-76 have been linked to chloroquine (CQ) as well as amodiaquine (AQ) resistance. mefloquine (MQ) and lumefantrine (LU) sensitivities are linked to Pfmdr1 86Y. Additionally, Pfcrt K76 allele carrying parasite...

The drug sensitivity characteristics and Plasmodium falciparum pfmdr1 status of five isolates of P. falciparum recently isolated from patients presenting for treatment from the Thailand/Myanmar border have been investigated. The aim of the study was to avoid the criticisms of some earlier studies by focusing on newly collected isolates from a specific geographic location. Three of the isolates ...

artesunate [6]. On the other hand, the potentially multigenic mechanism generally associated with quinoline antimalarial drugs offers hope for a slower development of resistance to lumefantrine. We presently favor the hypothesis that the selection of the pfmdr1 86N mutation is just the first step in a multistep process, as opposed to being a genetic background allowing the establishment of 1 mu...

To the Editor: Amplification and overexpression of the Plasmo-dium falciparum multidrug resistance 1 gene (Pfmdr1) have been associated with mefloquine resistance in P. Another isolate was obtained in a patient from Benin who did not respond clinically to mefloquine treatment (8). Pfmdr1 amplification has not been found in samples collected either before or after treatment for recurring P. falc...

1. Price RN, Uhlemann AC, Brockman A, McReady R, Ashley E, Phaipun L, et al. Mefloquine resistance in Plasmodium falciparum and increased pfmdr1 gene copy number. Lancet. 2004;364: 438–47. http://dx.doi.org/10.1016/S01406736(04)16767-6 2. Basco LK, Le Bras J, Rhoades Z, Wilson CM. Analysis of pfmdr1 and drug susceptibility in fresh isolates of Plasmodium falciparum from Subsaharan Africa. Mol B...

Genetic analysis of molecular markers is critical in tracking the emergence and/or spread of artemisinin resistant parasites. Clinical isolates collected in western Kenya pre- and post- introduction of artemisinin combination therapies (ACTs) were genotyped at SNP positions in regions of strong selection signatures on chromosome 13 and 14, as described in Southeast Asia (SEA). Twenty five SNPs ...