RESUMEN
Most Plasmodium vivax infections contain genetically distinct parasites, but the consequences of this polyclonality on the development of asexual parasites, their sexual differentiation, and their transmission remain unknown. We describe infections of Saimiri monkeys with two strains of P. vivax and the analyses of 80,024 parasites characterized by single cell RNA sequencing and individually genotyped. In our model, consecutive inoculations fail to establish polyclonal infections. By contrast, simultaneous inoculations of two strains lead to sustained polyclonal infections, although without detectable differences in parasite regulation or sexual commitment. Analyses of sporozoites dissected from mosquitoes fed on coinfected monkeys show that all genotypes are successfully transmitted to mosquitoes. However, after sporozoite inoculation, not all genotypes contribute to the subsequent blood infections, highlighting an important bottleneck during pre-erythrocytic development. Overall, these studies provide new insights on the mechanisms regulating the establishment of polyclonal P. vivax infections and their consequences for disease transmission.
Asunto(s)
Genotipo , Malaria Vivax , Plasmodium vivax , Saimiri , Análisis de la Célula Individual , Esporozoítos , Animales , Plasmodium vivax/genética , Plasmodium vivax/fisiología , Malaria Vivax/transmisión , Malaria Vivax/parasitología , Femenino , Culicidae/parasitología , Humanos , MasculinoRESUMEN
Plasmodium vivax variant interspersed repeats (vir) refer to the key protein used for escaping the host immune system. Knowledge in the genetic variation of vir genes can be used for the development of vaccines or diagnostic methods. Therefore, we evaluated the genetic diversity of the vir genes of P. vivax populations of several Asian countries, including Pakistan, which is a malaria-endemic country experiencing a significant rise in malaria cases in recent years. We analyzed the genetic diversity and population structure of 4 vir genes (vir 4, vir 12, vir 21, and vir 27) in the Pakistan P. vivax population and compared these features to those of the corresponding vir genes in other Asian countries. In Pakistan, vir 4 (S=198, H=9, Hd=0.889, Tajima's D value=1.12321) was the most genetically heterogenous, while the features of vir 21 (S=8, H=7, Hd=0.664, Tajima's D value =-0.63763) and vir 27 (S =25, H =11, Hd =0.682, Tajima's D value=-2.10836) were relatively conserved. Additionally, vir 4 was the most genetically diverse among Asian P. vivax populations, although within population diversity was low. Meanwhile, vir 21 and vir 27 among all Asian populations were closely related genetically. Our findings on the genetic diversity of vir genes and its relationships between populations in diverse geographical locations contribute toward a better understanding of the genetic characteristics of vir. The high level of genetic diversity of vir 4 suggests that this gene can be a useful genetic marker for understanding the P. vivax population structure. Longitudinal genetic diversity studies of vir genes in P. vivax isolates obtained from more diverse geographical areas are needed to better understand the function of vir genes and their use for the development of malaria control measures, such as vaccines.
Asunto(s)
Variación Genética , Malaria Vivax , Plasmodium vivax , Plasmodium vivax/genética , Pakistán/epidemiología , Variación Genética/genética , Humanos , Malaria Vivax/epidemiología , Malaria Vivax/parasitología , Malaria Vivax/genética , Genética de Población , Proteínas Protozoarias/genéticaRESUMEN
BACKGROUND: More than 95% of malaria transmission in Brazil occurs in the Legal Amazon Region, which in 2010 recorded around 333,429 cases reported in the Epidemiological Surveillance Information System-Malaria (Sivep_malaria), presenting an annual parasitic incidence (IPA) of 13.1 cases/1000 inhabitants. METHODS: This was a descriptive study that measured the community prevalence of Plasmodium infection and its relationship with land use in Três Fronteiras District, Colniza Municipality, Mato Grosso State. Data were collected during household visits in July 2011, with blood collection from finger pricks for the preparation of thick smear slides, and completion of a standardized case notification form. A georeferenced database was analysed, with land use evaluated as categorical variables. A kernel density map was built to show the density of cases and their location. RESULTS: Of the 621 respondents, 68(11%) had Plasmodium infection: 39 (57.4%) with Plasmodium vivax, 27(39.7%) with Plasmodium falciparum and two (2.9%) with mixed infections. Among infected individuals, 49 (72.1%) were men. Cases of malaria were distributed over the district, with greater occurrence of cases per household in open areas close to the mining company and artisanal mining sites. The was a greater density of cases located in the gold mining region. CONCLUSION: Transmission of malaria in Três Fronteiras District has a heterogeneous distribution. Individuals residing in mining and timber extraction sites have increased occurrence of Plasmodium infection.
Asunto(s)
Malaria Falciparum , Malaria Vivax , Población Rural , Brasil/epidemiología , Humanos , Femenino , Masculino , Adolescente , Adulto , Población Rural/estadística & datos numéricos , Persona de Mediana Edad , Adulto Joven , Niño , Preescolar , Malaria Vivax/epidemiología , Malaria Vivax/parasitología , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Prevalencia , Lactante , Anciano , Incidencia , Anciano de 80 o más Años , Plasmodium vivax , Malaria/epidemiología , Malaria/transmisiónRESUMEN
Challenges in classifying recurrent Plasmodium vivax infections constrain surveillance of antimalarial efficacy and transmission. Recurrent infections may arise from activation of dormant liver stages (relapse), blood-stage treatment failure (recrudescence) or reinfection. Molecular inference of familial relatedness (identity-by-descent or IBD) can help resolve the probable origin of recurrences. As whole genome sequencing of P. vivax remains challenging, targeted genotyping methods are needed for scalability. We describe a P. vivax marker discovery framework to identify and select panels of microhaplotypes (multi-allelic markers within small, amplifiable segments of the genome) that can accurately capture IBD. We evaluate panels of 50-250 microhaplotypes discovered in a global set of 615 P. vivax genomes. A candidate global 100-microhaplotype panel exhibits high marker diversity in the Asia-Pacific, Latin America and horn of Africa (median HE = 0.70-0.81) and identifies 89% of the polyclonal infections detected with genome-wide datasets. Data simulations reveal lower error in estimating pairwise IBD using microhaplotypes relative to traditional biallelic SNP barcodes. The candidate global panel also exhibits high accuracy in predicting geographic origin and captures local infection outbreak and bottlenecking events. Our framework is open-source enabling customised microhaplotype discovery and selection, with potential for porting to other species or data resources.
Asunto(s)
Malaria Vivax , Plasmodium vivax , Recurrencia , Plasmodium vivax/genética , Malaria Vivax/parasitología , Malaria Vivax/epidemiología , Humanos , Haplotipos/genética , Polimorfismo de Nucleótido Simple , Genoma de Protozoos/genética , GenotipoRESUMEN
PURPOSE: Primaquine (PQ) is recommended for radical cure of Plasmodium vivax (Pv) malaria, but its utilization is still limited due to high risk of severe haemolytic anaemia in patients with glucose-6-phosphate dehydrogenase deficiency (G6PD-d). The aim of the present study is to assess the different genotypic variants leading to G6PD-d in Delhi and Goa regions of India. METHODS: A total of 46 samples (34 retrospective Pv-mono-infected samples and 12 Pv-uninfected samples) were included in the study. Various genetic variants leading to G6PD-d were analysed by PCR amplification and DNA sequencing of different targeted exons of G6PD gene. RESULTS: Molecular analysis showed presence of four mutations in study population viz. 1311 C > T, 34.1% & IVSXI 93T > C, 45.5% and two novel mutations 1388G > T, 2.3% and 1398 C > T, 2.3% (silent mutation). The bioinformatics and computational analysis demonstrate that the slight conformational changes caused by R643L mutation in protein are deleterious in nature. CONCLUSION: The observed mutations do not clarify the role or association between G6PD-d and Pv-infected cases. Further investigation is required in order to fully comprehend and analyse the precise role of these mutations with context to malaria infections.
Asunto(s)
Deficiencia de Glucosafosfato Deshidrogenasa , Glucosafosfato Deshidrogenasa , Malaria Vivax , Plasmodium vivax , Humanos , Malaria Vivax/parasitología , India/epidemiología , Glucosafosfato Deshidrogenasa/genética , Plasmodium vivax/genética , Plasmodium vivax/enzimología , Deficiencia de Glucosafosfato Deshidrogenasa/genética , Estudios Retrospectivos , Genotipo , Mutación , Masculino , Variación Genética , Femenino , AdultoRESUMEN
CelTOS is a malaria vaccine antigen that is conserved in Plasmodium and other apicomplexan parasites and plays a role in cell-traversal. The structural basis and mechanisms of CelTOS-induced protective immunity to parasites are unknown. Here, CelTOS-specific monoclonal antibodies (mAbs) 7g7 and 4h12 demonstrated multistage activity, protecting against liver infection and preventing parasite transmission to mosquitoes. Both mAbs demonstrated cross-species activity with sterile protection against in vivo challenge with transgenic parasites containing either P. falciparum or P. vivax CelTOS, and with transmission reducing activity against P. falciparum. The mAbs prevented CelTOS-mediated pore formation providing insight into the protective mechanisms. X-ray crystallography and mutant-library epitope mapping revealed two distinct broadly conserved neutralizing epitopes. 7g7 bound to a parallel dimer of CelTOS, while 4h12 bound to a novel antiparallel dimer architecture. These findings inform the design of antibody therapies and vaccines and raise the prospect of a single intervention to simultaneously combat P. falciparum and P. vivax malaria.
Asunto(s)
Anticuerpos Monoclonales , Anticuerpos Antiprotozoarios , Vacunas contra la Malaria , Plasmodium falciparum , Plasmodium vivax , Anticuerpos Monoclonales/inmunología , Animales , Plasmodium falciparum/inmunología , Plasmodium vivax/inmunología , Vacunas contra la Malaria/inmunología , Anticuerpos Antiprotozoarios/inmunología , Ratones , Malaria Falciparum/inmunología , Malaria Falciparum/prevención & control , Malaria Falciparum/parasitología , Cristalografía por Rayos X , Epítopos/inmunología , Malaria Vivax/prevención & control , Malaria Vivax/inmunología , Malaria Vivax/parasitología , Antígenos de Protozoos/inmunología , Humanos , Femenino , Mapeo Epitopo , Malaria/inmunología , Malaria/prevención & control , Malaria/parasitología , Ratones Endogámicos BALB C , Proteínas Protozoarias/inmunología , Proteínas Protozoarias/químicaRESUMEN
Malaria is increasingly diagnosed in urban centers across the Amazon Basin. In this study, we combined repeated prevalence surveys over a 4-year period of a household-based random sample of 2,774 persons with parasite genotyping to investigate the epidemiology of malaria in Mâncio Lima, the main urban transmission hotspot in Amazonian Brazil. We found that most malarial infections were asymptomatic and undetected by point-of-care microscopy. Our findings indicate that as malaria transmission decreases, the detection threshold of microscopy rises, resulting in more missed infections despite similar parasite densities estimated by molecular methods. We identified genetically highly diverse populations of Plasmodium vivax and P. falciparum in the region; occasional shared lineages between urban and rural residents suggest cross-boundary propagation. The prevalence of low-density and asymptomatic infections poses a significant challenge for routine surveillance and the effectiveness of malaria control and elimination strategies in urbanized areas with readily accessible laboratory facilities.
Asunto(s)
Microscopía , Brasil/epidemiología , Humanos , Prevalencia , Microscopía/métodos , Femenino , Masculino , Adulto , Adolescente , Malaria Vivax/epidemiología , Malaria Vivax/parasitología , Niño , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Malaria Falciparum/prevención & control , Malaria/epidemiología , Malaria/transmisión , Malaria/prevención & control , Malaria/parasitología , Plasmodium vivax/genética , Población Urbana , Preescolar , Plasmodium falciparum/genética , Persona de Mediana Edad , Adulto Joven , Lactante , Historia del Siglo XXIRESUMEN
Myanmar aims to eliminate malaria by 2030. However, recent increase of malaria incidence is a great challenge to archive that goal. Increasing prevalence of Plasmodium vivax also hinders this endeavor. Monitoring genetic structure of the parasite is necessary to understand genetic nature and evolutionary aspect of P. vivax population in Myanmar. Partial fragment flanking blocks I and II of merozoite surface protein-3 alpha of P. vivax (pvmsp-3α) was amplified from P. vivax isolates collected in Pyin Oo Lwin, Mandalay Region, Myanmar in 2013-2015. Sequence analysis of pvmsp-3α was performed to determine genetic diversity and natural selection of this gene. Spatio-temporal genetic changes of pvmsp-3α in Myanmar P. vivax population were also investigated via comparative analysis of gene sequences obtained in this study and previously reported Myanmar pvmsp-3α sequences. Genetic diversity of Myanmar pvmsp-3α was detected in P. vivax isolates analyzed. Size polymorphisms in block I and amino acid changes and recombination events in block II were main factors contributing to the genetic diversity of pvmsp-3α. Comparative spatio-temporal analysis with previously reported Myanmar pvmsp-3α populations revealed the presence of genetic differences by population with moderate genetic differentiation between populations. Similar pattern of natural selection was also detected in Myanmar pvmsp-3α populations. These suggested that enough size of the P. vivax population sufficient to generate or maintain the genetic diversity remains in the population. Thus, continuous molecular surveillance of genetic structure of Myanmar P. vivax is necessary.
Asunto(s)
Antígenos de Protozoos , Variación Genética , Malaria Vivax , Filogenia , Plasmodium vivax , Proteínas Protozoarias , Análisis Espacio-Temporal , Plasmodium vivax/genética , Mianmar/epidemiología , Proteínas Protozoarias/genética , Malaria Vivax/parasitología , Malaria Vivax/epidemiología , Antígenos de Protozoos/genética , Humanos , Selección GenéticaRESUMEN
Plasmodium vivax, traditionally overlooked has experienced a notable increase in cases in East Africa. This study investigated the geographical origin and genetic diversity of P. vivax in Sudan using 14 microsatellite markers. A total of 113 clinical P. vivax samples were collected from two different ecogeographical zones, New Halfa and Khartoum, in Sudan. Additionally, 841 geographical samples from the database were incorporated for a global genetic analysis to discern genetic relationships among P. vivax isolates on regional and worldwide scales. On the regional scale, our findings revealed 91 unique and 8 shared haplotypes among the Sudan samples, showcasing a remarkable genetic diversity compared to other geographical isolates and supporting the hypothesis that P. vivax originated from Africa. On a global scale, distinct genetic clustering of P. vivax isolates from Africa, South America, and Asia (including Papua New Guinea and Solomon Island) was observed, with limited admixture among the three clusters. Principal component analysis emphasized the substantial contribution of African isolates to the observed global genetic variation. The Sudanese populations displayed extensive genetic diversity, marked by significant multi-locus linkage disequilibrium, suggesting an ancestral source of P. vivax variation globally and frequent recombination among the isolates. Notably, the East African P. vivax exhibited similarity with some Asian isolates, indicating potential recent introductions. Overall, our results underscore the effectiveness of utilizing microsatellite markers for implementing robust control measures, given their ability to capture extensive genetic diversity and linkage disequilibrium patterns.
Asunto(s)
Variación Genética , Haplotipos , Desequilibrio de Ligamiento , Malaria Vivax , Repeticiones de Microsatélite , Plasmodium vivax , Sudán/epidemiología , Plasmodium vivax/genética , Humanos , Malaria Vivax/parasitología , Malaria Vivax/epidemiología , Filogenia , FilogeografíaRESUMEN
The interactions of environmental, geographic, socio-demographic, and epidemiological factors in shaping mosquito-borne disease transmission dynamics are complex and changeable, influencing the abundance and distribution of vectors and the pathogens they transmit. In this study, 27 years of cross-sectional malaria survey data (1990-2017) were used to examine the effects of these factors on Plasmodium falciparum and Plasmodium vivax malaria presence at the community level in Africa and Asia. Monthly long-term, open-source data for each factor were compiled and analyzed using generalized linear models and classification and regression trees. Both temperature and precipitation exhibited unimodal relationships with malaria, with a positive effect up to a point after which a negative effect was observed as temperature and precipitation increased. Overall decline in malaria from 2000 to 2012 was well captured by the models, as was the resurgence after that. The models also indicated higher malaria in regions with lower economic and development indicators. Malaria is driven by a combination of environmental, geographic, socioeconomic, and epidemiological factors, and in this study, we demonstrated two approaches to capturing this complexity of drivers within models. Identifying these key drivers, and describing their associations with malaria, provides key information to inform planning and prevention strategies and interventions to reduce malaria burden.
Asunto(s)
Malaria Falciparum , Humanos , Estudios Transversales , África/epidemiología , Asia/epidemiología , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Malaria Falciparum/transmisión , Malaria Vivax/epidemiología , Malaria Vivax/parasitología , Malaria Vivax/transmisión , Factores Socioeconómicos , Geografía , Plasmodium falciparum , Malaria/epidemiología , Malaria/transmisión , Temperatura , Mosquitos Vectores/parasitología , Animales , Plasmodium vivax , AmbienteRESUMEN
The emergence and spread of chloroquine-resistant Plasmodium vivax have necessitated the assessment of alternative blood schizonticidal drugs. In Vietnam, chloroquine-resistant P. vivax malaria has been reported. In an open-label, single-arm trial, the safety, tolerability, and efficacy of pyronaridine-artesunate (Pyramax, PA) was evaluated in Dak Nong province, Vietnam. A 3-day course of PA was administered to adults and children (≥20 kg) infected with P. vivax. Patients also received primaquine (0.25 mg/kg daily for 14 days). PA was well tolerated with transient asymptomatic increases in liver transaminases. The per-protocol proportion of patients with day 42 PCR-unadjusted adequate clinical and parasitological response was 96.0% (95% CI, 84.9%-99.0%, n = 48/50). The median parasite clearance time was 12 h (range, 12-36 h), with a median fever clearance time of 24 h (range, 12-60 h). Single nucleotide polymorphisms (SNPs) as potential genetic markers of reduced drug susceptibility were analyzed in three putative drug resistance markers, Pvcrt-o, Pvmdr1, and PvK12. Insertion at position K10 of the Pvcrt-o gene was found in 74.6% (44/59) of isolates. Pvmdr1 SNPs at Y976F and F1076L were present in 61% (36/59) and 78% (46/59), respectively. Amplification of Pvmdr1 gene (two copies) was found in 5.1% (3/59) of parasite samples. Only 5.1% (3/59) of isolates had mutation 552I of the PvK12 gene. Overall, PA rapidly cleared P. vivax blood asexual stages and was highly efficacious in treating vivax malaria, with no evidence of artemisinin resistance found. PA provides an alternative to chloroquine treatment for vivax malaria in Vietnam. CLINICAL TRIALS: This study is registered with the Australian New Zealand Clinical Trials Registry as ACTRN12618001429246.
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Antimaláricos , Artemisininas , Artesunato , Malaria Vivax , Naftiridinas , Plasmodium vivax , Humanos , Malaria Vivax/tratamiento farmacológico , Malaria Vivax/parasitología , Naftiridinas/uso terapéutico , Antimaláricos/uso terapéutico , Artesunato/uso terapéutico , Vietnam , Adulto , Plasmodium vivax/efectos de los fármacos , Plasmodium vivax/genética , Masculino , Artemisininas/uso terapéutico , Adolescente , Niño , Femenino , Persona de Mediana Edad , Adulto Joven , Primaquina/uso terapéutico , Polimorfismo de Nucleótido Simple/genética , Preescolar , Proteínas Protozoarias/genética , Resistencia a Medicamentos/genética , Proteínas de Transporte de MembranaRESUMEN
Plasmodium vivax is now the main cause of malaria outside Africa. The gametocytocidal effects of antimalarial drugs are important to reduce malaria transmissibility, particularly in low-transmission settings, but they are not well characterized for P. vivax. The transmission-blocking effects of chloroquine, artesunate, and methylene blue on P. vivax gametocytes were assessed. Blood specimens were collected from patients presenting with vivax malaria, incubated with or without the tested drugs, and then fed to mosquitos from a laboratory-adapted colony of Anopheles dirus (a major malaria vector in Southeast Asia). The effects on oocyst and sporozoite development were analyzed under a multi-level Bayesian model accounting for assay variability and the heterogeneity of mosquito Plasmodium infection. Artesunate and methylene blue, but not chloroquine, exhibited potent transmission-blocking effects. Gametocyte exposures to artesunate and methylene blue reduced the mean oocyst count 469-fold (95% CI: 345 to 650) and 1,438-fold (95% CI: 970 to 2,064), respectively. The corresponding estimates for the sporozoite stage were a 148-fold reduction (95% CI: 61 to 470) and a 536-fold reduction (95% CI: 246 to 1,311) in the mean counts, respectively. In contrast, high chloroquine exposures reduced the mean oocyst count only 1.40-fold (95% CI: 1.20 to 1.64) and the mean sporozoite count 1.34-fold (95% CI: 1.12 to 1.66). This suggests that patients with vivax malaria often remain infectious to anopheline mosquitos after treatment with chloroquine. Use of artemisinin combination therapies or immediate initiation of primaquine radical cure should reduce the transmissibility of P. vivax infections.
Asunto(s)
Anopheles , Antimaláricos , Artesunato , Cloroquina , Malaria Vivax , Azul de Metileno , Plasmodium vivax , Azul de Metileno/farmacología , Azul de Metileno/uso terapéutico , Artesunato/farmacología , Artesunato/uso terapéutico , Cloroquina/farmacología , Cloroquina/uso terapéutico , Plasmodium vivax/efectos de los fármacos , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Malaria Vivax/tratamiento farmacológico , Malaria Vivax/parasitología , Malaria Vivax/transmisión , Animales , Humanos , Anopheles/parasitología , Anopheles/efectos de los fármacos , Esporozoítos/efectos de los fármacos , Artemisininas/farmacología , Artemisininas/uso terapéutico , Oocistos/efectos de los fármacosRESUMEN
Background: The integration of diagnostic methods holds promise for advancing the surveillance of malaria transmission in both endemic and non-endemic regions. Serological assays emerge as valuable tools to identify and delimit malaria transmission, serving as a complementary method to rapid diagnostic tests (RDT) and thick smear microscopy. Here, we evaluate the potential of antibodies directed against peptides encompassing the entire amino acid sequence of the PvMSP-1 Sal-I strain as viable serological biomarkers for P. vivax exposure. Methods: We screened peptides encompassing the complete amino acid sequence of the Plasmodium vivax Merozoite Surface Protein 1 (PvMSP-1) Sal-I strain as potential biomarkers for P. vivax exposure. Here, immunodominant peptides specifically recognized by antibodies from individuals infected with P. vivax were identified using the SPOT-synthesis technique followed by immunoblotting. Two 15-mer peptides were selected based on their higher and specific reactivity in immunoblotting assays. Subsequently, peptides p70 and p314 were synthesized in soluble form using SPPS (Solid Phase Peptide Synthesis) and tested by ELISA (IgG, and subclasses). Results: This study unveils the presence of IgG antibodies against the peptide p314 in most P. vivax-infected individuals from the Brazilian Amazon region. In silico B-cell epitope prediction further supports the utilization of p314 as a potential biomarker for evaluating malaria transmission, strengthened by its amino acid sequence being part of a conserved block of PvMSP-1. Indeed, compared to patients infected with P. falciparum and uninfected individuals never exposed to malaria, P. vivax-infected patients have a notably higher recognition of p314 by IgG1 and IgG3.
Asunto(s)
Anticuerpos Antiprotozoarios , Biomarcadores , Malaria Vivax , Proteína 1 de Superficie de Merozoito , Plasmodium vivax , Humanos , Malaria Vivax/inmunología , Malaria Vivax/sangre , Malaria Vivax/parasitología , Malaria Vivax/transmisión , Malaria Vivax/diagnóstico , Proteína 1 de Superficie de Merozoito/inmunología , Plasmodium vivax/inmunología , Biomarcadores/sangre , Anticuerpos Antiprotozoarios/inmunología , Anticuerpos Antiprotozoarios/sangre , Inmunoglobulina G/inmunología , Inmunoglobulina G/sangre , Adulto , Femenino , Masculino , Persona de Mediana Edad , Péptidos/inmunología , Ensayo de Inmunoadsorción Enzimática/métodos , Adulto Joven , Adolescente , Secuencia de AminoácidosRESUMEN
BACKGROUND: Plasmodium vivax has become the predominant species in the border regions of Thailand. The emergence and spread of antimalarial drug resistance in P. vivax is one of the significant challenges for malaria control. Continuous surveillance of drug resistance is therefore necessary for monitoring the development of drug resistance in the region. This study aims to investigate the prevalence of the mutation in the P. vivax multidrug resistant 1 (Pvmdr1), dihydrofolate reductase (Pvdhfr), and dihydropteroate synthetase (Pvdhps) genes conferred resistance to chloroquine (CQ), pyrimethamine (P) and sulfadoxine (S), respectively. METHOD: 100 P. vivax isolates were obtained between January to May 2023 from a Kanchanaburi province, western Thailand. Nucleotide sequences of Pvmdr1, Pvdhfr, and Pvdhps genes were amplified and sequenced. The frequency of single nucleotide polymorphisms (SNPs)-haplotypes of drug-resistant alleles was assessed. The linkage disequilibrium (LD) tests were also analyzed. RESULTS: In Pvmdr1, T958M, Y976F, and F1076L, mutations were detected in 100%, 21%, and 23% of the isolates, respectively. In Pvdhfr, the quadruple mutant allele (I57R58M61T117) prevailed in 84% of the samples, followed by (L57R58M61T117) in 11%. For Pvdhps, the double mutant allele (G383G553) was detected (48%), followed by the triple mutant allele (G383M512G553) (47%) of the isolates. The most prevalent combination of Pvdhfr (I57R58M61T117) and Pvdhps (G383G553) alleles was sextuple mutated haplotypes (48%). For LD analysis, the association in the SNPs pairs was found between the intragenic and intergenic regions of the Pvdhfr and Pvdhps genes. CONCLUSION: The study has recently updated the high prevalence of three gene mutations associated with CQ and SP resistance. Genetic monitoring is therefore important to intensify in the regions to further assess the spread of drug resistant. Our data also provide evidence on the distribution of drug resistance for the early warning system, thereby threatening P. vivax malaria treatment policy decisions at the national level.
Asunto(s)
Antimaláricos , Resistencia a Medicamentos , Malaria Vivax , Plasmodium vivax , Polimorfismo de Nucleótido Simple , Plasmodium vivax/genética , Plasmodium vivax/efectos de los fármacos , Plasmodium vivax/aislamiento & purificación , Tailandia/epidemiología , Resistencia a Medicamentos/genética , Humanos , Antimaláricos/farmacología , Malaria Vivax/parasitología , Malaria Vivax/epidemiología , Malaria Vivax/tratamiento farmacológico , Tetrahidrofolato Deshidrogenasa/genética , Desequilibrio de Ligamiento , Mutación , Proteínas Protozoarias/genética , Cloroquina/farmacología , Dihidropteroato Sintasa/genética , Sulfadoxina/farmacología , Pirimetamina/farmacología , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Haplotipos , Masculino , Femenino , AdultoRESUMEN
An improved understanding of the Plasmodium vivax populations in the Great Mekong Subregion (GMS) is needed to monitor the progress of malaria elimination. This study aimed to use a P. vivax single nucleotide polymorphism (SNP) barcode to evaluate the population dynamics and explore the gene flow among P. vivax parasite populations in the western GMS (China, Myanmar and Thailand). A total of 315 P. vivax patient samples collected in 2011 and 2018 from four regions of the western GMS were genotyped for 42 SNPs using the high-throughput MassARRAY SNP genotyping technology. Population genetic analysis was conducted to estimate the genetic diversity, effective population size, and population structure among the P. vivax populations. Overall, 291 samples were successfully genotyped at 39 SNPs. A significant difference was observed in the proportion of polyclonal infections among the five P. vivax populations (P = 0.0012, Pearson Chi-square test, χ2 = 18.1), with western Myanmar having the highest proportion (96.2%, 50/52) in 2018. Likewise, the average complexity of infection was also highest in western Myanmar (1.31) and lowest in northeast Myanmar (1.01) in 2018. The older samples from western China in 2011 had the highest pairwise nucleotide diversity (π, 0.388 ± 0.046), expected heterozygosity (He, 0.363 ± 0.02), and the largest effective population size. In comparison, in the neighboring northeast Myanmar, the more recent samples in 2018 showed the lowest values (π, 0.224 ± 0.036; He, 0.220 ± 0.026). Furthermore, the 2018 northeast Myanmar parasites showed high and moderate genetic differentiation from other populations with FST values of 0.162-0.252, whereas genetic differentiation among other populations was relatively low (FST ≤ 0.059). Principal component analysis, phylogeny, and STRUCTURE analysis showed that the P. vivax population in northeast Myanmar in 2018 substantially diverged from other populations. Although the 42 SNP barcode is a valuable tool for tracking parasite origins of worldwide parasite populations, a more extended barcode with additional SNPs is needed to distinguish the more related parasite populations in the western GMS.
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Código de Barras del ADN Taxonómico , Malaria Vivax , Plasmodium vivax , Polimorfismo de Nucleótido Simple , Plasmodium vivax/genética , Plasmodium vivax/clasificación , Humanos , Malaria Vivax/parasitología , Malaria Vivax/epidemiología , Mianmar/epidemiología , Tailandia/epidemiología , Genotipo , China/epidemiología , Variación Genética , Flujo GénicoRESUMEN
Asymptomatic malaria can impact existing malaria control and elimination efforts around the world, particularly in Africa, where the majority of malaria cases and death occurs. This is a cross-sectional study aimed to determine the prevalence and predictors of asymptomatic malaria among migrant farmworkers from June to July 2020 in the Upper Awash Agro-industry, East Shewa zone, Oromia Regional State, Ethiopia. A total of 254 migrant farmworkers without signs and symptoms of malaria were enrolled. Data on socio-demographic characteristics and malaria prevention practices were obtained through a structured questionnaire. Venous blood samples were collected and diagnosed using microscopy, rapid diagnostic tests, and polymerase chain reaction (PCR). Data were coded, entered, and analyzed using SPSS version-21 statistical software. Multivariable logistic regression was used to assess associated factors. A p < 0.05 was considered statistically significant. The overall prevalence of asymptomatic malaria among farmworkers in this study was 5.1% [95% CI 1.6, 6.7]. The proportions of Plasmodium falciparum was 90.0% (9/10) while it was 10.0% (1/10) for Plasmodium vivax. Out of the microscopy and/or RDT-confirmed malaria cases, (n = 9; 100%) were confirmed to be P. falciparum by nested PCR, while (n = 3/122; 2.46%) were found to be P. falciparum among 50% negative cases with the microscopy and/or RDT. The gametocyte stage was detected in 40% of microscopically positive cases out of which 44.4% belongs to P. falciparum. Home area/origin of migrant laborers [AOR = 6.08, (95% CI 1.08, 34.66)], family history of malaria [AOR = 8.15, (95% CI 1.43, 46.44)], and outdoor sleeping [AOR = 10.14, (95% CI 1.15, 89.14)] were significantly associated with asymptomatic malaria. In conclusion, asymptomatic malaria was detected among farmworkers in the study area and it was significantly associated with outdoor sleeping, home area, and family history of malaria. Prevention tools and control strategies, particularly focusing on migrant farmworkers, should be considered to support the ongoing malaria control and elimination effort in Ethiopia.
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Agricultores , Migrantes , Humanos , Etiopía/epidemiología , Migrantes/estadística & datos numéricos , Femenino , Masculino , Adulto , Estudios Transversales , Prevalencia , Adulto Joven , Adolescente , Malaria/epidemiología , Malaria/parasitología , Persona de Mediana Edad , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Malaria Falciparum/diagnóstico , Plasmodium falciparum/aislamiento & purificación , Plasmodium falciparum/genética , Plasmodium falciparum/patogenicidad , Infecciones Asintomáticas/epidemiología , Plasmodium vivax/aislamiento & purificación , Factores de Riesgo , Malaria Vivax/epidemiología , Malaria Vivax/parasitologíaRESUMEN
Hard-to-reach communities represent Peru's main challenge for malaria elimination, but information about transmission in these areas is scarce. Here, we assessed Plasmodium vivax (Pv) and P. falciparum (Pf) transmission dynamics, resistance markers, and Pf hrp2/3 deletions in Nueva Jerusalén (NJ), a remote, indigenous community in the Peruvian Amazon with high population mobility. We collected samples from November 2019 to May 2020 by active (ACD) and passive case detection (PCD) in NJ. Parasites were identified with microscopy and PCR. Then, we analyzed a representative set of positive-PCR samples (Pv = 68, Pf = 58) using highly-multiplexed deep sequencing assays (AmpliSeq) and compared NJ parasites with ones from other remote Peruvian areas using population genetics indexes. The ACD intervention did not reduce malaria cases in the short term, and persistent malaria transmission was observed (at least one Pv infection was detected in 96% of the study days). In Nueva Jerusalen, the Pv population had modest genetic diversity (He = 0.27). Pf population had lower diversity (He = 0.08) and presented temporal clustering, one of these clusters linked to an outbreak in February 2020. Moreover, Pv and Pf parasites from NJ exhibited variable levels of differentiation (Pv Fst = 0.07-0.52 and Pf Fst = 0.11-0.58) with parasites from other remote areas. No artemisin resistance mutations but chloroquine (57%) and sulfadoxine-pyrimethamine (35-67%) were detected in NJ's Pf parasites. Moreover, pfhrp2/3 gene deletions were common (32-50% of parasites with one or both genes deleted). The persistent Pv transmission and the detection of a Pf outbreak with parasites genetically distinct from the local ones highlight the need for tailored interventions focusing on mobility patterns and imported infections in remote areas to eliminate malaria in the Peruvian Amazon.
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Malaria Falciparum , Malaria Vivax , Plasmodium falciparum , Plasmodium vivax , Proteínas Protozoarias , Perú/epidemiología , Humanos , Plasmodium falciparum/genética , Plasmodium falciparum/aislamiento & purificación , Plasmodium vivax/genética , Plasmodium vivax/aislamiento & purificación , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Malaria Falciparum/transmisión , Malaria Vivax/epidemiología , Malaria Vivax/parasitología , Malaria Vivax/transmisión , Proteínas Protozoarias/genética , Femenino , Masculino , Niño , Adulto , Antimaláricos/uso terapéutico , Antimaláricos/farmacología , Adolescente , Resistencia a Medicamentos/genética , Persona de Mediana Edad , Pueblos Indígenas/genética , Adulto Joven , Preescolar , Genómica/métodos , Variación Genética , Antígenos de Protozoos/genéticaRESUMEN
BACKGROUND: Plasmodium vivax is the main causative agent of malaria in Panama. However, the prevalence of asymptomatic infections in the different endemic regions remains unknown. Understanding the epidemiological behavior of asymptomatic infections is essential for the elimination of malaria. This study aimed to determine the prevalence of asymptomatic malarial infections in one of the main endemic regions of Panama using multiplex real-time reverse transcription RT-MqPCR. METHODS: A cross-sectional study was conducted in three communities in the Guna Yala Comarca. A total of 551 thick blood smears and their respective samples on filter paper were collected from volunteers of different ages and sexes from June 20 to 25, 2016. Infections by the Plasmodium spp. were diagnosed using microscopy and RT-MqPCR. All statistical analyses were performed using the R software. RESULTS: The average prevalence of asymptomatic infections by P. vivax in the three communities detected by RT-MqPCR was 9.3%, with Ukupa having the highest prevalence (13.4%), followed by Aidirgandi (11.1%) and Irgandi (3.3%). A total of 74 samples were diagnosed as asymptomatic infections using RT-MqPCR. Light microscopy (LM) detected that 17.6% (13/74) of the asymptomatic samples and 82.4% (61/74) were diagnosed as false negatives. A 100% correlation was observed between samples diagnosed using LM and RT-MqPCR. A total of 52.7% (39/74) of the asymptomatic patients were female and 85.1% (63/74) were registered between the ages of 1 and 21 years. Factors associated with asymptomatic infection were community (aOR = 0.38 (95% CI 0.17-0.83), p < 0.001) and age aOR = 0.98 (95% CI 0.97-1.00), p < 0.05); F = 5.38; p < 0.05). CONCLUSIONS: This study provides novel evidence of the considerable prevalence of asymptomatic P. vivax infections in the endemic region of Kuna Yala, representing a new challenge that requires immediate attention from the National Malaria Program. The results of this study provide essential information for the health authorities responsible for developing new policies. Furthermore, it will allow program administrators to reorient and design effective malaria control strategies that consider asymptomatic infections as a fundamental part of malaria control and move towards fulfilling their commitment to eliminate it.
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Malaria Vivax , Plasmodium vivax , Humanos , Panamá/epidemiología , Femenino , Masculino , Adulto , Estudios Transversales , Adolescente , Malaria Vivax/epidemiología , Malaria Vivax/diagnóstico , Malaria Vivax/parasitología , Plasmodium vivax/genética , Plasmodium vivax/aislamiento & purificación , Adulto Joven , Niño , Persona de Mediana Edad , Prevalencia , Infecciones Asintomáticas/epidemiología , Preescolar , Pueblos Indígenas/genética , Lactante , Reacción en Cadena en Tiempo Real de la Polimerasa/métodosRESUMEN
BACKGROUND: Plasmodium vivax is the most predominant malaria species in Latin America, constituting 71.5% of malaria cases in 2021. With several countries aiming for malaria elimination, it is crucial to prioritize effectiveness of national control programs by optimizing the utilization of available resources and strategically implementing necessary changes. To support this, there is a need for innovative approaches such as genomic surveillance tools that can investigate changes in transmission intensity, imported cases and sources of reintroduction, and can detect molecular markers associated with drug resistance. METHODOLOGY/PRINCIPAL FINDINGS: Here, we apply a modified highly-multiplexed deep sequencing assay: Pv AmpliSeq v2 Peru. The tool targets a newly developed 41-SNP Peru barcode for parasite population analysis within Peru, the 33-SNP vivaxGEN-geo panel for country-level classification, and 11 putative drug resistance genes. It was applied to 230 samples from the Peruvian Amazon (2007-2020), generating baseline surveillance data. We observed a heterogenous P. vivax population with high diversity and gene flow in peri-urban areas of Maynas province (Loreto region) with a temporal drift using all SNPs detected by the assay (nSNP = 2909). In comparison, in an indigenous isolated area, the parasite population was genetically differentiated (FST = 0.07-0.09) with moderate diversity and high relatedness between isolates in the community. In a remote border community, a clonal P. vivax cluster was identified, with distinct haplotypes in drug resistant genes and ama1, more similar to Brazilian isolates, likely representing an introduction of P. vivax from Brazil at that time. To test its applicability for Latin America, we evaluated the SNP Peru barcode in P. vivax genomes from the region and demonstrated the capacity to capture local population clustering at within-country level. CONCLUSIONS/SIGNIFICANCE: Together this data shows that P. vivax transmission is heterogeneous in different settings within the Peruvian Amazon. Genetic analysis is a key component for regional malaria control, offering valuable insights that should be incorporated into routine surveillance.
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Malaria Vivax , Plasmodium vivax , Polimorfismo de Nucleótido Simple , Plasmodium vivax/genética , Plasmodium vivax/aislamiento & purificación , Plasmodium vivax/clasificación , Perú/epidemiología , Malaria Vivax/epidemiología , Malaria Vivax/parasitología , Humanos , Resistencia a Medicamentos/genética , Genoma de Protozoos , Secuenciación de Nucleótidos de Alto Rendimiento , Monitoreo Epidemiológico , GenómicaRESUMEN
In malaria parasites, the erythrocyte binding-like proteins (EBL) are a family of invasion proteins that are attractive vaccine targets. In the case of Plasmodium vivax, the widespread malaria parasite, blood-stage vaccines have been largely focused on a single EBL candidate, the Duffy binding-like domain (DBL) of the Duffy binding protein (DBPII), due to its well-characterized role in the reticulocyte invasion. A novel P. vivax EBL family member, the Erythrocyte binding protein (EBP2, also named EBP or DBP2), binds preferentially to reticulocytes and may mediate an alternative P. vivax invasion pathway. To gain insight into the natural genetic diversity of the DBL domain of EBP2 (region II; EBP2-II), we analyzed ebp2-II gene sequences of 71 P. vivax isolates collected in different endemic settings of the Brazilian Amazon rainforest, where P. vivax is the predominant malaria-associated species. Although most of the substitutions in the ebp2-II gene were non-synonymous and suggested positive selection, the results showed that the DBL domain of the EBP2 was much less polymorphic than that of DBPII. The predominant EBP2 haplotype in the Amazon region corresponded to the C127 reference sequence first described in Cambodia (25% C127-like haplotype). An overview of ebp2-II gene sequences available at GenBank (n = 352) from seven countries (Cambodia, Madagascar, Myanmar, PNG, South Korea, Thailand, Vietnam) confirmed the C127-like haplotype as highly prevalent worldwide. Two out of 43 haplotypes (5 to 20 inferred per country) showed a global frequency of 60%. The results presented here open new avenues of research pursuit while suggesting that a vaccine based on the DBL domain of EBP2 should target a few haplotypes for broad coverage.