Evaluation of community-based systems for the surveillance of day three-positive Plasmodium falciparum cases in Western Cambodia

Abstract

BackgroundDelayed clearance of Plasmodium falciparum parasites is used as an operational indicator of potential artemisinin resistance. Effective community-based systems to detect P. falciparum cases remaining positive 72 hours after initiating treatment would be valuable for guiding case follow-up in areas of known resistance risk and for detecting areas of emerging resistance.MethodsSystems incorporating existing networks of village malaria workers (VMWs) to monitor day three-positive P. falciparum cases were piloted in three provinces in western Cambodia. Quantitative and qualitative data were used to evaluate the wider feasibility and sustainability of community-based surveillance of day three-positive P. falciparum cases.ResultsOf 294 day-3 blood slides obtained across all sites (from 297 day-0 positives), 63 were positive for P. falciparum, an overall day-3 positivity rate of 21%. There were significant variations in the systems implemented by different partners. Full engagement of VMWs and health centre staff is critical. VMWs are responsible for a range of individual tasks including preparing blood slides on day-0, completing forms, administering directly observed therapy (DOT) on days 0–2, obtaining follow-up slides on day-3 and transporting slides and paperwork to their supervising health centre. When suitably motivated, unsalaried VMWs are willing and able to produce good quality blood smears and achieve very high rates of DOT and day-3 follow-up.ConclusionsCommunity-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. The purpose and role of community-based day-3 surveillance should be assessed in the light of resource requirements; scaling-up would need to be systematic and targeted, based on clearly defined epidemiological criteria. To be truly comprehensive, the system would need to be extended beyond VMWs to other public and private health providers.

Reactive case-detection of malaria in Pailin Province, Western Cambodia: lessons from a year-long evaluation in a pre-elimination setting

“…Each of the 114 villages has two VMWs who are trained to diagnose malaria infections using rapid diagnostic tests (RDT), and to provide treatment according to national guidelines. VMWs routinely collect blood films and filter paper blood spots and send a short message service (SMS) to alert the public health facility and the national malaria programme when a new malaria case is identified [ 30 ]. At the initial time of this study, the first-line treatment in Pailin was atovaquone-proguanil (AP, Malarone, GlaxoSmithKline) and then shifted to dihydroartemisinin–piperaquine (DHA–PQP) towards the middle of the study until the end.…”

Genetic features of P. falciparum parasites collected in 2012-2016 and anti-malaria resistance along China-Myanmar border

“…However, following the widespread resistance to CQ and other antimalarial drugs, P.falciparum parasites produced resistance to DHA-PIP too, shortly after it was widely used in Southeast Asia, initially showing prolonged parasite clearance time (PCT) and subsequently treatment failures as the partner drug also failed [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. The epicenter of the resistance was Cambodia where CQ resistance had also been first emerged [1][2][11][12][13][14][15][16][17][18][19][20]. This resistance rapidly spread to other neighboring countries, such as Thailand, Vietnam, laos, PDR and Myanmar, which all are part of the Greater Mekong sub-region (GMS) countries [25][26][27][28].…”

“…A few studies revealed that the decreasing efficiency of DHA-PIP in the GMS involved resistance to both DHA and PIP [11][12][13][14][15][16][17][18][19][20][21]. Based on the single nucleotide polymorphisms (SNPs) examination and correction analysis with genomic tools, mutant K13-propeller alleles, such as C580Y, R539T, Y493H, I543T, were verified to be correlated with the spread of resistance in west Cambodia and other GMS countries [29].…”

“…This finding alerted close attention to K13 mutation of P.falciparum parasites world widely. Furthermore, because the resistance of P.falciparum to the fast-acting artemtisinin component meaning longer exposure of the parasite to the long-acting partner drugs, the more chances of parasite survival [11][12][13][14][15][16][17][18][19][20][21], the resistance to PIP appeared too in the same place where artemisinin-resistant parasites were first reported. Genome-wide association studies revealing that amplification of two protease genes plasmepsin 2/3 (PfPM2/3) was associated with clinical resistance to PIP in Cambodia, established makers for resistance of parasites to PIP [30][31].…”

National Malaria Prevalence in Cambodia: Microscopy Versus Polymerase Chain Reaction Estimates

“…[1][2][3][4] In 2011, Cambodia committed itself to eliminating malaria by 2025. This goal may be challenged by the emergence of multidrug-resistant, including artemisinin-resistant Plasmodium falciparum (ART-R) [5][6][7][8] and, now, the demise of dihydroartemisinin-piperaquine.…”