Despite the high burden of Plasmodium vivax malaria in South Asian countries, the genetic diversity of circulating parasite populations is not well described. Determinants of antimalarial drug susceptibility for P. vivax in the region have not been characterised. Our genomic analysis of global P. vivax (n = 558) establishes South Asian isolates (n = 92) as a distinct subpopulation, which shares ancestry with some East African and South East Asian parasites. Signals of positive selection are linked to drug resistance-associated loci including pvkelch10, pvmrp1, pvdhfr and pvdhps, and two loci linked to P. vivax invasion of reticulocytes, pvrbp1a and pvrbp1b. Significant identity-by-descent was found in extended chromosome regions common to P. vivax from India and Ethiopia, including the pvdbp gene associated with Duffy blood group binding. Our investigation provides new understanding of global P. vivax population structure and genomic diversity, and genetic evidence of recent directional selection in this important human pathogen.

BackgroundPregnancy poses specific challenges for the diagnosis of Plasmodium falciparum infection due to parasite sequestration in the placenta, which translates in low circulation levels in peripheral blood. The aim of this study is to assess the performance of a new highly sensitive rapid diagnostic test (HS-RDT) for the detection of malaria in peripheral and placental blood samples from pregnant women in Colombia.MethodsThis is a retrospective study using 737 peripheral and placental specimens collected from pregnant women in Colombian malaria-endemic regions. Light microscopy (LM), conventional rapid diagnostic tests (Pf/Pv RDT and Pf RDT), and HS-RDT testing were performed. Diagnostic accuracy endpoints of LM, HS-RDT and RDTs were compared with nested polymerase chain reaction (nPCR) as the reference test.ResultsIn comparison with nPCR, the sensitivity of HS-RDT, Pf RDT, Pf/Pv RDT and LM to detect infection in peripheral samples was 85.7% (95% CI = 70.6–93.7), 82.8% (95% CI = 67.3–91.9), 77.1% (95% CI = 61.0–87.9) and 77.1% (95% CI = 61.0–87.9) respectively. The sensitivity to detect malaria in asymptomatic women, was higher with HS-RDT, where LM and Pf/Pv RDT missed half of infections detected by nPCR, but differences were not significant. Overall, specificity was similar for all tests (>99.0%). In placental blood, the prevalence of infection by P. falciparum by nPCR was 2.8% (8/286), by HS-RDT was 1% and by conventional RDTs (Pf RDT and Pf/Pv RDT) and LM was 0.7%. The HS-RDT detected placental infections in peripheral blood that were negative by LM and Pf/Pv RDT, however the number of positive placentas was low.ConclusionsThe sensitivity of HS-RDT to detect P. falciparum infections in peripheral and placental samples from pregnant women was slightly better compared to routinely used tests during ANC visits and at delivery. Although further studies are needed to guide recommendations on the use of the HS-RDT for malaria case management in pregnancy, this study shows the potential value of this test to diagnose malaria in pregnancy in low-transmission settings.

This report describes the MalariaGEN Pv4 dataset, a new release of curated genome variation data on 1,895 samples of Plasmodium vivax collected at 88 worldwide locations between 2001 and 2017. It includes 1,370 new samples contributed by MalariaGEN and VivaxGEN partner studies in addition to previously published samples from these and other sources. We provide genotype calls at over 4.5 million variable positions including over 3 million single nucleotide polymorphisms (SNPs), as well as short indels and tandem duplications. This enlarged dataset highlights major compartments of parasite population structure, with clear differentiation between Africa, Latin America, Oceania, Western Asia and different parts of Southeast Asia. Each sample has been classified for drug resistance to sulfadoxine, pyrimethamine and mefloquine based on known markers at the dhfr, dhps and mdr1 loci. The prevalence of all of these resistance markers was much higher in Southeast Asia and Oceania than elsewhere. This open resource of analysis-ready genome variation data from the MalariaGEN and VivaxGEN networks is driven by our collective goal to advance research into the complex biology of P. vivax and to accelerate genomic surveillance for malaria control and elimination.

Background: The humoral immune response against Anopheles salivary glands proteins in the vertebrate host can reflect the intensity of exposure to Anopheles bites and the risk of Plasmodium infection. In Colombia, the identification of exposure biomarkers is necessary due to the several Anopheles species circulating. The purpose of this study was to evaluate risk of malaria infection by measuring antibody responses against salivary glands extracts from Anopheles (Nyssorhynchus) albimanus and Anopheles (Nys.) darlingi and also against the gSG6-P1 peptide of Anopheles gambiae in people residing in a malaria endemic area in the Colombian Pacific coast. Methods: Dried blood spots samples were eluted to measure the IgG antibodies against salivary gland extracts of An. albimanus strains STECLA (STE) and Cartagena (CTG) and An. darlingi and the gSG6-P1 peptide by ELISA in uninfected people and microscopic and submicroscopic Plasmodium carriers from the Colombia Pacific Coast. A multiple linear mixed regression model, Spearman correlation, and Mann-Whitney U-test were used to analyse IgG data. Results: Significant differences in specific IgG levels were detected between infected and uninfected groups for salivary glands extracts from An. albimanus and for gSG6-P1, also IgG response to CTG and gSG6-P1 peptide were positively associated with the IgG response to Plasmodium falciparum in the mixed model. Conclusion: The CTG and STE An. albimanus salivary glands extracts are a potential source of new Anopheles salivary biomarkers to identify exposure to the main malaria vector and to calculate risk of disease in the Colombian Pacific coast. Also, the gSG6-P1 peptide has the potential to quantify human exposure to the subgenus Anopheles vectors in the same area.

Abstract. In malaria-endemic regions of Latin America, little is known about malaria in pregnancy. To characterize the clinical and laboratory findings of maternal infection, we evaluated 166 cases of pregnant women infected with Plasmodium spp. in a prospective study conducted in northwestern Colombia during [2005][2006]. A total of 89.8% (149 of 166) had fever or a history of fever in the past 48 hours, 9.0% (15 of 166) had severe malaria, of which 66.7% was caused by Plasmodium vivax and 33.3% by P. falciparum. Hepatic dysfunction was the main complication (9 of 15) observed. The proportion of severe cases was similar for both species (P = 0.41). In malaria-endemic areas of Colombia, malaria in pregnancy has a broad clinical spectrum. In pregnant women, P. vivax infection frequently leads to organspecific complications.