Dihydroartemisinin-piperaquine is the current frontline artemisinin combination therapy (ACT) for Plasmodium falciparum malaria in Cambodia but is now failing in several western provinces.
Spatial aggregation of malaria parasite carriers, and the identification of malaria species-specific risk factors provide key insights in malaria epidemiology in low transmission settings, which can guide targeted supplementary interventions.
The clinical burden of falciparum malaria in most areas of Cambodia has greatly decreased from 2009 to 2013, associated with roll-out of ITNs and VMWs.
This paper explores the utility of routine malaria surveillance data for the stratification of malaria risk in Cambodia, where the target is malaria elimination by 2025.
Dihydroartemisinin-piperaquine, the current first-line drug for uncomplicated malaria caused by Plasmodium falciparum and Plasmodium vivax in Cambodia, was previously shown to be of benefit as malaria chemoprophylaxis when administered as a monthly 3-day regimen.
Community-based surveillance of day-3 P. falciparum cases is feasible, but highly intensive, and as such needs strong and continuous support, particularly supervision and training.
We aimed to assess whether an in-vitro ring-stage survival assay (RSA) can identify culture-adapted P falciparum isolates from patients with slow-clearing or fast-clearing infections, to investigate the stage-dependent susceptibility of parasites to dihydroartemisinin in the in-vitro RSA, and to assess whether an ex-vivo RSA can identify artemisinin-resistant P falciparum infections.
The parasites responsible for artemisinin-resistant malaria in a clinical trial in Western Cambodia comprise the dominant clones of acute malaria infections rather than minority clones emerging during treatment.
In Cambodia, outdoor malaria transmission in villages and forest plots is important.
The objective was to determine which of these two common assays is more appropriate for studying drug susceptibility of "immediate ex vivo" (IEV) isolates, analysed without culture adaption, in a region of relatively low malaria transmission.