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Volume 13, Number 5—May 2007
Letter

Resistance to Dihydroartemisinin

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To the Editor: The title of the letter by Cojean et al. (1) is misleading. The data presented essentially point to an absence of in vitro resistance to dihydroartemisinin (dhART) in the panel of African isolates studied, with 1 of 397 isolates having an elevated 50% inhibitory concentration (IC50) for dhART. The S769N PfATPase6 mutation associated with in vitro resistance to artemether (2) was observed in 1 isolate. This mutant isolate had a low IC50 for dhART, but its IC50 for artemether has not been tested. Since the relationship between in vitro susceptibility to artemether and dhART is still uncertain (3), these data do not disprove the association of a PfATPase6 S769N polymorphism with elevated IC50 for artemether that was observed in isolates from French Guiana (2).

Worth noting is that the association of the S769N PfATPase6 polymorphism with elevated IC50 for artemether was confirmed in an isolate collected in French Guiana in 2005; that isolate had an IC50 for artemether of 127 nmol/L. Molecular typing identified 2 clonal types, 1 with a wild-type PfATPase6 allele and 1 with a S769N single mutant. After 3 weeks of in vitro cultivation without drug, the mutant allele was no longer detected and the IC50 for artemether was 8.2 nmol/L. This finding suggests poor fitness of the mutant allele under standard culture conditions.

The observation of an additional case of in vitro resistance to artemether in French Guiana 3 years after the first cases is of concern. Reinforcement of surveillance is needed as is clarification of the relationship of in vitro susceptibility to artemether and artesunate, the derivatives currently included in artemisinin-based combination therapies (ACTs). Surveillance and clarification would be particularly timely since emerging clinical or parasitologic failures to some ACTs have been reported (4,5).

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Eric Legrand*Comments to Author , Beatrice Volney*, Jean-Baptiste Meynard*, Philippe Esterre*, and Odile Mercereau-Puijalon†
Author affiliations: *Institut Pasteur de la Guyane, Cayenne, French Guiana; †Institut Pasteur, Paris, France

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References

  1. Cojean  S, Hubert  V, Le Bras  J, Durand  R. Resistance to dihydroartemisinin. Emerg Infect Dis. 2006;12:17989.PubMedGoogle Scholar
  2. Jambou  R, Legrand  E, Niang  M, Ing  NK, Lim  P, Volney  B, In vitro artemether resistance of Plasmodium falciparum field isolates and point mutations pf the SERCA-type PfATPase6. Lancet. 2005;366:19603. DOIPubMedGoogle Scholar
  3. Brockman  A, Price  RN, van Vugt  M, Heppner  DG, Walsh  D, Sookto  P, Plasmodium falciparum antimalarial drug susceptibility on the north-western border of Thailand during five years of extensive use of artesunate-mefloquine. Trans R Soc Trop Med Hyg. 2000;94:53744. DOIPubMedGoogle Scholar
  4. Grandesso  F, Hagerman  A, Kamara  S, Lam  E, Checchi  F, Balkan  S, Low efficacy of the combination artesunate plus amodiaquine for uncomplicated falciparum malaria among children under 5 in Kailahun, Sierra Leone. Trop Med Int Health. 2006;11:101721. DOIPubMedGoogle Scholar
  5. Bukirwa  H, Yeka  A, Kamya  MR, Talisuna  A, Banek  K, Bakyaita  N, Artemisinin combination therapies for treatment of uncomplicated malaria in Uganda. PLoS Clin Trials. 2006;1:e7 . DOIPubMedGoogle Scholar

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Cite This Article

DOI: 10.3201/eid1305.061442

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In response: The original title of our article was “Lack of Plasmodium falciparum in Vitro and Genomic Resistance to Dihydroartemisinin in Travelers Returning to France from Africa.” EID’s shortening of the title (1) led to the perception that the letter title was misleading, but it was not on purpose. We have recently tested the 50% inhibitory concentration for artemether of the S769N PfATPase6 isolate that we had kept in liquid nitrogen, and it showed susceptibility.

We underline that the previously reported clinical or parasitologic failures to some artemisinin-based combination therapies (2,3) were not synonymous with the emergence of resistance to artemisinin compounds. In the study by Grandesso et al., a combination of artesunate plus amodiaquine was given to children <5 years of age who lived in an area in which amodiaquine alone was ineffective to adequately treat uncomplicated falciparum malaria in 1 of 3 cases at day 28 (2). Such a combination (artesunate plus amodiaquine) was nearly equivalent in 1 of 3 cases to a 3-day artesunate monotherapy, which may fail to completely cure children because of the short half-life of artesunate. In the study by Bukirwa et al., no recrudescence occurred in patients treated with artesunate plus amodiaquine and only 2 of 199 patients treated with artemether plus lumefantrine experienced recrudescence at day 28 (3). As Birkiwa et al. themselves acknowledged, artemether plus lumefantrine was not administered with food, and it is known that lumefantrine is absorbed better when it is taken with a small amount of fat. Thus, the clinical failures observed did not necessarily reflect P. falciparum resistance to artemisinin compounds.

Rémy Durand, Hôpital Avicenne, Laboratoire de Parasitologie Mycologie, 125 rue de Stalingrad, 93009 Bobigny Cedex, France
Author affiliations: *Hôpital Bichat Claude Bernard, Paris, France; †Université Paris 5; Paris, France; ‡Hôpital Avicenne, Bobigny, France; §Université Paris 13, Bobigny, France

References

  1. Cojean  S, Hubert  V, Le Bras  J, Durand  R. Resistance to dihydroartemisinin. Emerg Infect Dis. 2006;12:17989.PubMedGoogle Scholar
  2. Grandesso  F, Hagerman  A, Kamara  S, Lam  E, Checchi  F, Balkan  S, Low efficacy of the combination artesunate plus amodiaquine for uncomplicated falciparum malaria among children under 5 in Kailahun, Sierra Leone. Trop Med Int Health. 2006;11:101721. DOIPubMedGoogle Scholar
  3. Bukirwa  H, Yeka  A, Kamya  MR, Talisuna  A, Banek  K, Bakyaita  N, Artemisinin combination therapies for treatment of uncomplicated malaria in Uganda. PLoS Clin Trials. 2006;1:e7. DOIPubMedGoogle Scholar

Table of Contents – Volume 13, Number 5—May 2007

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Comments

Please use the form below to submit correspondence to the authors or contact them at the following address:

Address for correspondence: Eric Legrand, Institut Pasteur–CNRCP, 23 Ave Pasteur, PO Box 6010, Cayenne, French Guiana 97306;

Rémy Durand, Hôpital Avicenne, Laboratoire de Parasitologie Mycologie, 125 rue de Stalingrad, 93009 Bobigny Cedex, France

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Page created: May 08, 2012
Page updated: May 08, 2012
Page reviewed: May 08, 2012
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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