Abstract
BackgroundThe emergence and spread of artemisinin resistance in Plasmodium falciparum poses a threat to malaria eradication, including China’s plan to eliminate malaria by 2020. Piperaquine (PPQ) resistance has emerged in Cambodia, compromising an important partner drug that is widely used in China in the form of dihydroartemisinin (DHA)-PPQ. Several mutations in a P. falciparum gene encoding a kelch protein on chromosome 13 (k13) are associated with artemisinin resistance and have arisen spread in the Great Mekong subregion, including the China–Myanmar border. Multiple copies of the plasmepsin II/III (pm2/3) genes, located on chromosome 14, have been shown to be associated with PPQ resistance.MethodsThe therapeutic efficacy of DHA-PPQ for the treatment of uncomplicated P. falciparum was evaluated along the China–Myanmar border from 2010 to 2014. The dry blood spots samples collected in the efficacy study prior DHA-PPQ treatment and from the local hospital by passive detection were used to amplify k13 and pm2. Polymorphisms within k13 were genotyped by capillary sequencing and pm2 copy number was quantified by relative-quantitative real-time polymerase chain reaction. Treatment outcome was evaluated with the World Health Organization protocol. A linear regression model was used to estimate the association between the day 3 positive rate and k13 mutation and the relationship of the pm2 copy number variants and k13 mutations.ResultsDHA-PPQ was effective for uncomplicated P. falciparum infection in Yunnan Province with cure rates > 95%. Twelve non synonymous mutations in the k13 domain were observed among the 268 samples with the prevalence of 44.0% and the predominant mutation was F446I with a prevalence of 32.8%. Only one sample was observed with multi-copies of pm2, including parasites with and without k13 mutations. The therapeutic efficacy of DHA-PPQ was > 95% along the China–Myanmar border, consistent with the lack of amplification of pm2.ConclusionDHA-PPQ for uncomplicated P. falciparum infection still showed efficacy in an area with artemisinin-resistant malaria along the China–Myanmar border. There was no evidence to show PPQ resistance by clinical study and molecular markers survey. Continued monitoring of the parasite population using molecular markers will be important to track emergence and spread of resistance in this region.
Highlights
The emergence and spread of artemisinin resistance in Plasmodium falciparum poses a threat to malaria eradication, including China’s plan to eliminate malaria by 2020
The emergence and spread of artemisinin resistance in Plasmodium falciparum poses a threat to malaria control and eradication goals in the Greater Mekong subregion (GMS), where resistance has emerged independently and spread [4,5,6,7]
We investigated the therapeutic efficacy of DHA-PPQ for treatment of uncomplicated P. falciparum along the China–Myanmar borders from 2010 to 2014
Summary
The emergence and spread of artemisinin resistance in Plasmodium falciparum poses a threat to malaria eradication, including China’s plan to eliminate malaria by 2020. Several mutations in a P. falciparum gene encoding a kelch protein on chromosome 13 (k13) are associ‐ ated with artemisinin resistance and have arisen spread in the Great Mekong subregion, including the China–Myan‐ mar border. Artemisinin-based combination therapy (ACT), which combines a fast-acting, rapidly eliminated artemisinin derivative with another slower-acting partner drug with a longer half-life, have played an indispensable role in reducing global malaria-associated mortality and morbidity [2]. The emergence and spread of artemisinin resistance in Plasmodium falciparum poses a threat to malaria control and eradication goals in the Greater Mekong subregion (GMS), where resistance has emerged independently and spread [4,5,6,7]. The WHO has implemented a strategy to eliminate P. falciparum from the six countries located in the GMS by 2025 to respond the threat of an untreatable multi-drug resistant parasite [8]
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