Volume 76, Issue 4
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645


Artemisinin combination therapies (ACTs) have recently been adopted as first-line therapy for infections in most malaria-endemic countries. In this study, we estimated the association between artesunate-mefloquine therapy failure and genetic changes in the putative transporter, . Blood samples were acquired from 80 patients enrolled in an 2004 efficacy study in Pailin, Cambodia, and genotyped for copy number and haplotype. Having parasites with three or more copies of before treatment was strongly associated with recrudescence (hazard ratio [HR] = 8.30; 95% CI: 2.60–26.43). This relationship was maintained when controlling for initial parasite density and hematocrit (HR = 7.91; 95% CI: 2.38–26.29). Artesunate-mefloquine treatment selected for increased copy number, because isolates from recurrent episodes had higher copy numbers than the paired enrollment samples (Wilcoxon rank test, = 0.040). copy number should be evaluated further as a surveillance tool for artesunate-mefloquine resistance in Cambodia.


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  1. Payne D, 1987. Spread of chloroquine resistance in Plasmodium falciparum. Parasitol Today 3 : 241–246.
  2. Fontanet AL, Johnson BD, Walker AM, Bergqvist Y, Hellgrn U, Rooney W, 1994. Falciparum malaria in eastern Thailand: a randomized trial of the efficacy of a single dose of mefloquine. Bull World Health Organ 72 : 73–78.
  3. Yeung S, Pongtavornpinyo W, Hastings IM, Mills AJ, White NJ, 2004. Antimalarial drug resistance, artemisinin-based combination therapy, and the contribution of modeling to elucidating policy choices. Am J Trop Med Hyg 71 : 179–186.
  4. World Health Organization, 2005. Susceptibility of Plasmodium falciparum to Antimalarial Drugs: Report on Global Monitoring: 1996–2004. Geneva: World Health Organization.
  5. Vijaykadga S, Rojanawatsirivet C, Cholpol S, Phoungmanee D, Nakavej A, Wongsrichanalai C, 2006. In vivo sensitivity monitoring of mefloquine monotherapy and artesunate-mefloquine combinations for the treatment of uncomplicated falciparum malaria in Thailand in 2003. Trop Med Int Health 11 : 211–219.
  6. Mey Bouth D, Tsuyuoka R, Poravuth Y, Narann TS, Seila S, Lim C, Incardona S, Lim P, Sem R, Socheat D, Christophel E, Ringwald P, 2006. Surveillance of the efficacy of artesunate and mefloquine combination for the treatment of uncomplicated falciparum malaria in Cambodia. Trop Med Int Health 11 : 1360–1366.
  7. Bloland PB, Ettling M, 1999. Making malaria-treatment policy in the face of drug resistance. Ann Trop Med Parasitol 93 : 5–23.
  8. Olliaro P, 2005. Drug resistance hampers our capacity to roll back malaria. Clin Infect Dis 41 : S247–S257.
  9. Khim N, Bouchier C, Ekala MT, Incardona S, Lim P, Legrand E, Jambou R, Doung S, Puijalon OM, Fandeur T, 2005. Countrywide survey shows very high prevalence of Plasmodium falciparum multilocus resistance genotypes in Cambodia. Antimicrob Agents Chemother 49 : 3147–3152.
  10. Duraisingh MT, Roper C, Walliker D, Warhurst DC, 2000. Increased sensitivity to the antimalarials mefloquine and artemisinin is conferred by mutations in the pfmdr1 gene of Plasmodium falciparum. Mol Microbiol 36 : 955–961.
  11. Pickard AL, Wongsrichanalai C, Purfield A, Kamwendo D, Emery K, Zalewski C, Kawamoto F, Miller RS, Meshnick SR, 2003. Resistance to antimalarials in Southeast Asia and genetic polymorphisms in pfmdr1. Antimicrob Agents Chemother 47 : 2418–2423.
  12. Price RN, Cassar C, Brockman A, Duraisingh M, van Vugt M, White NJ, Nosten F, Krishna S, 1999. The pfmdr1 gene is associated with a multidrug-resistant phenotype in Plasmodium falciparum from the western border of Thailand. Antimicrob Agents Chemother 43 : 2943–2949.
  13. Nelson AL, Purfield A, McDaniel P, Uthaimongkol N, Buathong N, Sriwichai S, Miller RS, Wongsrichanalai C, Meshnick SR, 2005. pfmdr1 genotyping and in vivo mefloquine resistance on the Thai-Myanmar border. Am J Trop Med Hyg 72 : 586–592.
  14. Reed MB, Saliba KJ, Caruana SR, Kirk K, Cowman AF, 2000. Pgh1 modulates sensitivity and resistance to multiple antimalarials in Plasmodium falciparum. Nature 403 : 906–909.
  15. Sidhu AB, Valderramos SG, Fidock DA, 2005. pfmdr1 mutations contribute to quinine resistance and enhance mefloquine and artemisinin sensitivity in Plasmodium falciparum. Mol Microbiol 57 : 913–926.
  16. Cowman AF, Galatis D, Thompson JK, 1994. Selection for mefloquine resistance in Plasmodium falciparum is linked to amplification of the pfmdr1 gene and cross-resistance to halofantrine and quinine. Proc Natl Acad Sci USA 91 : 1143–1147.
  17. World Health Organization, 2003. Assessment and Monitoring of Antimalarial Drug Efficacy for the Treatment of Uncomplicated Falciparum Malaria. Geneva: World Health Organization.
  18. Farnert A, Arez AP, Babiker HA, Beck HP, Benito A, Bjorkman A, Bruce MC, Conway DJ, Day KP, Henning L, Mercereau-Puijalon O, Ranford-Cartwright LC, Rubio JM, Snounou G, Walliker D, Zwetyenga J, do Rosario VE, 2001. Genotyping of Plasmodium falciparum infections by PCR: A comparative multicentre study. Trans R Soc Trop Med Hyg 95 : 225–232.
  19. Durrand V, Berry A, Sem R, Glaziou P, Beaudou J, Fandeur T, 2004. Variations in the sequence and expression of the Plasmodium falciparum chloroquine resistance transporter (Pfcrt) and their relationship to chloroquine resistance in vitro. Mol Biochem Parasitol 136 : 273–285.
  20. Purfield A, Nelson A, Laoboonchai A, Congpuong K, McDaniel P, Miller RS, Welch K, Wongsrichanalai C, Meshnick SR, 2004. A new method for detection of pfmdr1 mutations in Plasmodium falciparum DNA using real-time PCR. Malaria J 3 : 9.
  21. Price RN, Uhlemann AC, Brockman A, McGready R, Ashley E, Phaipun L, Patel R, Laing K, Looareesuwan S, White NJ, Nosten F, Krishna S, 2004. Mefloquine resistance in Plasmodium falciparum and increased pfmdr1 gene copy number. Lancet 364 : 438–447.
  22. Ferreira ID, do Rosario VE, Cravo PV, 2006. Real-time quantitative PCR with SYBR Green I detection for estimating copy numbers of nine drug resistance candidate genes in Plasmodium falciparum. Malaria J 5 : 1.
  23. Wellems TE, Panton LJ, Gluzman IY, do Rosario VE, Gwadz RW, Walker-Jonah A, Krogstad DJ, 1990. Chloroquine resistance not linked to mdr-like genes in a Plasmodium falciparum cross. Nature 345 : 253–255.
  24. Collett D, 2003. Modelling Survival Data in Medical Research. Boca Raton, FL: CRC Press.
  25. Poole C, 2001. Low p-values or narrow confidence intervals: Which are more durable? Epidemiology 12 : 291–294.
  26. Greenland S, Pearl J, Robins JM, 1999. Causal diagrams for epidemiologic research. Epidemiology 10 : 37–48.
  27. Greenland S, 1999. Re: Confidence limits made easy: interval estimation using a substitution method. Am J Epidemiol 149 : 884.
  28. Price RN, Nosten F, Luxemburger C, van Vugt M, Phaipun L, Chongsuphajaisiddhi T, White NJ, 1998. Artesunate/mefloquine treatment of multi-drug resistant falciparum malaria. Trans R Soc Trop Med Hyg 91: 574–577.
  29. Mawili-Mboumba DP, Kun JF, Lell B, Kremsner PG, Ntoumi F, 2002. Pfmdr1 alleles and response to ultralow-dose mefloquine treatment in Gabonese patients. Antimicrob Agents Chemother 46 : 166–170.
  30. Pillai DR, Hijar G, Montoya Y, Marouino W, Ruebush TK 2nd, Wongsrichanalai C, Kain KC, 2003. Lack of prediction of mefloquine and mefloquine-artesunate treatment outcome by mutations in the Plasmodium falciparum multidrug resistance 1 (pfmdr1) gene for P. falciparum malaria in Peru. Am J Trop Med Hyg 68 : 107–110.
  31. Ittarat W, Pickard AL, Rattanasinganchan P, Wilairatana P, Looareesuwan S, Emery K, Low J, Udomsangpetch R, Meshnick SR, 2003. Recrudescence in artesunate-treated patients with falciparum malaria is dependent on parasite burden not on parasite factors. Am J Trop Med Hyg 68 : 147–152.
  32. Lim P, Chim P, Sem R, Nemh S, Poravuth Y, Lim C, Seila S, Tsuyuoka R, Denis MB, Socheat D, Fandeur T, 2005. In vitro monitoring of Plasmodium falciparum susceptibility to artesunate, mefloquine, quinine and chloroquine in Cambodia: 2001–2002. Acta Trop 93 : 31–40.
  33. Karbwang J, White NJ, 1990. Clinical pharmacokinetics of mefloquine. Clin Pharmacokinet 19 : 264–279.
  34. Teja-Isavadharm P, Watt G, Eamsila C, Jongsakul K, Li Q, Keeratithakul G, Sirisopana N, Luesutthiviboon L, Brewer TG, Kyle DE, 2001. Comparative pharmacokinetics and effect kinetics of orally administered artesunate in healthy volunteers and patients with uncomplicated falciparum malaria. Am J Trop Med Hyg 65 : 717–721.
  35. Hastings IM, Ward SA, 2005. Coartem (artemether-lumefantrine) in Africa: The beginning of the end? J Infect Dis 192 : 1303–1304; author reply 1304–1305.
  36. Denis MB, Kouznetsov RL, Giboda M, 1991. In vivo response of multi-resistant Plasmodium falciparum infections to mefloquine and its combination with sulfadoxine/pyrimethamine in Cambodia. Folia Parasitol (Praha) 38 : 187–188.
  37. Thimasarn K, Sirichaisinthop J, Vijaykadga S, Tansophalaks S, Yamokgul P, Laomiphol A, Palananth C, Thamewat U, Thaithong S, Rooney W, 1995. In vivo study of the response of Plasmodium falciparum to standard mefloquine/sulfadoxine/pyrimethamine (MSP) treatment among gem miners returning from Cambodia. Southeast Asian J Trop Med Public Health 26 : 204–212.
  38. Stepniewska K, Taylor WR, Mayxay M, Price R, Smithuis F, Guthmann JP, Barnes K, Myint HY, Adjuik M, Olliaro P, Pukrittayakamee S, Looareesuwan S, Hien TT, Farrar J, Nosten F, Day NP, White NJ, 2004. In vivo assessment of drug efficacy against Plasmodium falciparum malaria: Duration of follow-up. Antimicrob Agents Chemother 48 : 4271–4280.
  39. Price RN, Uhlemann AC, van Vugt M, Brockman A, Hutagalung R, Nair S, Nash D, Singhasivanon P, Anderson T, Krishna S, White NJ, 2006. Molecular and pharmacological determinants of therapeutic response to artemether-lumefantrine in multi-drug-resistant Plasmodium falciparum malaria. Clin Infect Dis 42 : 1570–1577.

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  • Received : 12 Sep 2006
  • Accepted : 01 Jan 2007

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