Ex vivo piperaquine resistance developed rapidly in Plasmodium falciparum isolates in northern Cambodia compared to ThailandReport as inadecuate

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Malaria Journal

, 15:519

First Online: 21 October 2016Received: 15 June 2016Accepted: 07 October 2016DOI: 10.1186-s12936-016-1569-y

Cite this article as: Chaorattanakawee, S., Lon, C., Jongsakul, K. et al. Malar J 2016 15: 519. doi:10.1186-s12936-016-1569-y


BackgroundThe recent dramatic decline in dihydroartemisinin-piperaquine DHA-PPQ efficacy in northwestern Cambodia has raised concerns about the rapid spread of piperaquine resistance just as DHA-PPQ is being introduced as first-line therapy in neighbouring countries.

MethodsEx vivo parasite susceptibilities were tracked to determine the rate of progression of DHA, PPQ and mefloquine MQ resistance from sentinel sites on the Thai–Cambodian and Thai–Myanmar borders from 2010 to 2015. Immediate ex vivo IEV histidine-rich protein 2 HRP-2 assays were used on fresh patient Plasmodium falciparum isolates to determine drug susceptibility profiles.

ResultsIEV HRP-2 assays detected the precipitous emergence of PPQ resistance in Cambodia beginning in 2013 when 40 % of isolates had an IC90 greater than the upper limit of prior years, and this rate doubled to 80 % by 2015. In contrast, Thai–Myanmar isolates from 2013 to 14 remained PPQ-sensitive, while northeastern Thai isolates appeared to have an intermediate resistance profile. The opposite trend was observed for MQ where Cambodian isolates appeared to have a modest increase in overall sensitivity during the same period, with IC50 declining to median levels comparable to those found in Thailand. A significant association between increased PPQ IC50 and IC90 among Cambodian isolates with DHA-PPQ treatment failure was observed. Nearly all Cambodian and Thai isolates were deemed artemisinin resistant with a >1 % survival rate for DHA in the ring-stage assay RSA, though there was no correlation among isolates to indicate cross-resistance between PPQ and artemisinins.

ConclusionsClinical DHA-PPQ failures appear to be associated with declines in the long-acting partner drug PPQ, though sensitivity appears to remain largely intact for now in western Thailand. Rapid progression of PPQ resistance associated with DHA-PPQ treatment failures in northern Cambodia limits drugs of choice in this region, and urgently requires alternative therapy. The temporary re-introduction of artesunate AS-MQ is the current response to PPQ resistance in this area, due to inverse MQ and PPQ resistance patterns. This will require careful monitoring for re-emergence of MQ resistance, and possible simultaneous resistance to all three drugs AS, MQ and PPQ.

KeywordsMalaria Drug resistance Piperaquine Mefloquine Cambodia Thailand AbbreviationsASartesunate



IEVimmediate ex vivo

HRP-2histidine-rich protein 2

ELISAenzyme-linked immunosorbent assay

IC5050 % inhibitory concentration

IC9090 % inhibitory concentration

RSAring-stage survival assay

PSApiperaquine survival assay

ACTartemisinin combination therapy

PCRpolymerase chain reaction

TACTtriple artemisinin combination therapy

PVPreah Vihear

OMOddar Meanchey


KRCHKwai River Christian Hospital

ODoptical density

IQRinterquartile range


Pfmdr1P. falciparum multi-drug resistance gene


WHOWorld Health Organization

Electronic supplementary materialThe online version of this article doi:10.1186-s12936-016-1569-y contains supplementary material, which is available to authorized users.

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Author: Suwanna Chaorattanakawee - Chanthap Lon - Krisada Jongsakul - Jariyanart Gawee - Somethy Sok - Siratchana Sundrakes - Nareth

Source: https://link.springer.com/

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