ABSTRACT
Traditionally, patient travel history has been used to distinguish imported from autochthonous malaria cases, but the dormant liver stages of Plasmodium vivax confound this approach. Molecular tools offer an alternative method to identify, and map imported cases. Using machine learning approaches incorporating hierarchical fixation index and decision tree analyses applied to 799 P. vivax genomes from 21 countries, we identified 33-SNP, 50-SNP and 55-SNP barcodes (GEO33, GEO50 and GEO55), with high capacity to predict the infection's country of origin. The Matthews correlation coefficient (MCC) for an existing, commonly applied 38-SNP barcode (BR38) exceeded 0.80 in 62% countries. The GEO panels outperformed BR38, with median MCCs > 0.80 in 90% countries at GEO33, and 95% at GEO50 and GEO55. An online, open-access, likelihood-based classifier framework was established to support data analysis (vivaxGEN-geo). The SNP selection and classifier methods can be readily amended for other use cases to support malaria control programs.
Subject(s)
Malaria, Vivax , Malaria , Humans , Malaria, Vivax/diagnosis , Malaria, Vivax/genetics , Likelihood Functions , Plasmodium vivax/genetics , InternetABSTRACT
Self-medication with antimalarial drugs is a major factor in the development of drug resistance, exerting subtherapeutic drug pressure on circulating parasite populations. Data on self-medication with antimalarials from the Southern Pacific coast region of Colombia, where 4-aminoquinolines resistance and political instability prevail, are vital to elimination strategies. We present results of an exploratory study of 254 individuals having malaria symptoms who sought malaria diagnosis in two hospitals in Tumaco, Department of Nariño, Colombia. Thirty-two percent (82/254) of participants had positive Saker-Solomons urine tests, indicating self-medication with chloroquine (CQ) before consultation for diagnosis. Notably, among 30 pregnant women participating in the study, 43% were Saker--Solomons positive. Molecular analysis of the K76T position encoded by the pfcrt gene revealed the mutant allele in all four samples that were both positive for Plasmodium falciparum and positive for the Saker-Solomons test, suggesting persistent CQ pressure. The high frequency of self-medication, particularly among pregnant women merits attention by public health authorities and comprehensive investigation.
