RESUMEN
Background: Plasmodium vivax malaria has been one of the most troublesome diseases in the Democratic People's Republic of Korea (DPRK). Given that a majority of malaria cases are concentrated near the demilitarized zone, concerted elimination efforts from both the Republic of Korea (ROK) and DPRK are essential for a malaria-free Korean Peninsula. This study assessed the impact of rapid diagnostic tests (RDTs) and tafenoquine on malaria incidence in DPRK. Methods: We patterned the current model structure from the previously developed Plasmodium vivax malaria dynamic transmission model for ROK. Model parameters were adjusted using demographic and climate data from malaria-risk areas in DPRK, and the model was calibrated to annual malaria incidences from 2014 to 2018 in DPRK, as reported by the World Health Organization. Subsequently, we estimated the preventable malaria cases over a decade after introducing RDTs and tafenoquine compared to using microscopy alone and primaquine, respectively. Sensitivity analysis was performed to account for uncertainty in model parameters. Results: When comparing RDTs to microscopy, a one-day reduction in diagnostic time due to the introduction of RDTs led to a reduction in malaria incidence by 26,235 cases (65.6%) over the next decade. With a two-day reduction, incidences decreased by 33,635 (84.1%). When comparing a single dose of tafenoquine with a 14-day primaquine regimen, the former prevented 1,222 (77.5%) relapse cases and 4,530 (11.3%) total cases over the years. Conclusion: The continuous and simultaneous implementation of RDTs and tafenoquine emerges as a potent strategy to considerably reduce malaria in DPRK.
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Antimaláricos , Malaria Vivax , Malaria Vivax/epidemiología , Malaria Vivax/prevención & control , Humanos , Antimaláricos/uso terapéutico , Incidencia , República Popular Democrática de Corea/epidemiología , Plasmodium vivax/efectos de los fármacos , Aminoquinolinas/uso terapéutico , Pruebas Diagnósticas de Rutina/estadística & datos numéricos , Adulto , Masculino , Persona de Mediana EdadRESUMEN
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.
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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
Plasmodium vivax is the most geographically widespread malaria parasite. P. vivax has the ability to remain dormant (as a hypnozoite) in the human liver and subsequently reactivate, which makes control efforts more difficult. Given the majority of P. vivax infections are due to hypnozoite reactivation, targeting the hypnozoite reservoir with a radical cure is crucial for achieving P. vivax elimination. Stochastic effects can strongly influence dynamics when disease prevalence is low or when the population size is small. Hence, it is important to account for this when modelling malaria elimination. We use a stochastic multiscale model of P. vivax transmission to study the impacts of multiple rounds of mass drug administration (MDA) with a radical cure, accounting for superinfection and hypnozoite dynamics. Our results indicate multiple rounds of MDA with a high-efficacy drug are needed to achieve a substantial probability of elimination. This work has the potential to help guide P. vivax elimination strategies by quantifying elimination probabilities for an MDA approach.
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Antimaláricos , Erradicación de la Enfermedad , Malaria Vivax , Administración Masiva de Medicamentos , Plasmodium vivax , Humanos , Malaria Vivax/prevención & control , Malaria Vivax/tratamiento farmacológico , Malaria Vivax/epidemiología , Administración Masiva de Medicamentos/estadística & datos numéricos , Plasmodium vivax/efectos de los fármacos , Plasmodium vivax/fisiología , Erradicación de la Enfermedad/métodos , Erradicación de la Enfermedad/estadística & datos numéricos , Antimaláricos/uso terapéutico , Antimaláricos/administración & dosificación , Procesos Estocásticos , Simulación por ComputadorRESUMEN
Australian Defence Force (ADF) personnel train and operate in malarious regions that include neighboring countries with high burden and species with latent hepatic parasites.1 We summarized longitudinal malaria case data, following a prior 10-year period review to 2007.2 Malaria case entries within the ADF Malaria and Infectious Diseases Institute (ADFMIDI)-managed Central Malaria Register (CMR) were examined. Data from cases confirmed between January 1, 2008 through December 31, 2022 were analyzed. Sixty ADF members were diagnosed with malaria, including 1 with a mixed Plasmodium falciparum and P. vivax infection. Of 61 malaria infections, 69% (42 of 61) were P. vivax. P. vivax infection resulted in delayed initial case presentation (more than 4 weeks after exposure) in at least 36% (15 of 42) of cases, and 5 personnel experienced further relapse. Most P. vivax infections were acquired in the U.S. Indo-Pacific Command (INDOPACOM) and P. falciparum in the U.S. Africa Command (AFRICOM) regions. The ADF experienced ongoing reduced malaria case incidence following high rates in the early 2000s. Maintenance of prophylactic vigilance, both for eradicating dormant hypnozoites and preventing P. vivax relapse, remains important, however.
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Malaria Falciparum , Malaria Vivax , Personal Militar , Humanos , Personal Militar/estadística & datos numéricos , Australia/epidemiología , Masculino , Femenino , Adulto , Malaria Vivax/epidemiología , Malaria Falciparum/epidemiología , Adulto Joven , Incidencia , Persona de Mediana Edad , Plasmodium vivax/aislamiento & purificación , Malaria/epidemiología , Plasmodium falciparum/aislamiento & purificación , Sistema de RegistrosRESUMEN
BACKGROUND: Despite the successful efforts in controlling malaria in Vietnam, the disease remains a significant health concern, particularly in Central Vietnam. This study aimed to assess correlations between environmental, climatic, and socio-economic factors in the district with malaria cases. METHODS: The study was conducted in 15 provinces in Central Vietnam from January 2018 to December 2022. Monthly malaria cases were obtained from the Institute of Malariology, Parasitology, and Entomology Quy Nhon, Vietnam. Environmental, climatic, and socio-economic data were retrieved using a Google Earth Engine script. A multivariable Zero-inflated Poisson regression was undertaken using a Bayesian framework with spatial and spatiotemporal random effects with a conditional autoregressive prior structure. The posterior random effects were estimated using Bayesian Markov Chain Monte Carlo simulation with Gibbs sampling. RESULTS: There was a total of 5,985 Plasmodium falciparum and 2,623 Plasmodium vivax cases during the study period. Plasmodium falciparum risk increased by five times (95% credible interval [CrI] 4.37, 6.74) for each 1-unit increase of normalized difference vegetation index (NDVI) without lag and by 8% (95% CrI 7%, 9%) for every 1ºC increase in maximum temperature (TMAX) at a 6-month lag. While a decrease in risk of 1% (95% CrI 0%, 1%) for a 1 mm increase in precipitation with a 6-month lag was observed. A 1-unit increase in NDVI at a 1-month lag was associated with a four-fold increase (95% CrI 2.95, 4.90) in risk of P. vivax. In addition, the risk increased by 6% (95% CrI 5%, 7%) and 3% (95% CrI 1%, 5%) for each 1ºC increase in land surface temperature during daytime with a 6-month lag and TMAX at a 4-month lag, respectively. Spatial analysis showed a higher mean malaria risk of both species in the Central Highlands and southeast parts of Central Vietnam and a lower risk in the northern and north-western areas. CONCLUSION: Identification of environmental, climatic, and socio-economic risk factors and spatial malaria clusters are crucial for designing adaptive strategies to maximize the impact of limited public health resources toward eliminating malaria in Vietnam.
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Teorema de Bayes , Clima , Malaria Falciparum , Malaria Vivax , Factores Socioeconómicos , Análisis Espacio-Temporal , Vietnam/epidemiología , Malaria Falciparum/epidemiología , Malaria Vivax/epidemiología , Humanos , Ambiente , Plasmodium falciparum , Plasmodium vivax/fisiologíaRESUMEN
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.
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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.
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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
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.
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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
BACKGROUND: The government of Lao PDR has increased efforts to control malaria transmission in order to reach its national elimination goal by 2030. Weather can influence malaria transmission dynamics and should be considered when assessing the impact of elimination interventions but this relationship has not been well characterized in Lao PDR. This study examined the space-time association between climate variables and Plasmodium falciparum and Plasmodium vivax malaria incidence from 2010 to 2022. METHODS: Spatiotemporal Bayesian modelling was used to investigate the monthly relationship, and model selection criteria were used to evaluate the performance of the models and weather variable specifications. As the malaria control and elimination situation was spatially and temporally dynamic during the study period, the association was examined annually at the provincial level. RESULTS: Malaria incidence decreased from 2010 to 2022 and was concentrated in the southern regions for both P. falciparum and P. vivax. Rainfall and maximum humidity were identified as most strongly associated with malaria during the study period. Rainfall was associated with P. falciparum incidence in the north and central regions during 2010-2011, and with P. vivax incidence in the north and central regions during 2012-2015. Maximum humidity was persistently associated with P. falciparum and P. vivax incidence in the south. CONCLUSIONS: Malaria remains prevalent in Lao PDR, particularly in the south, and the relationship with weather varies between regions but was strongest for rainfall and maximum humidity for both species. During peak periods with suitable weather conditions, vector control activities and raising public health awareness on the proper usage of intervention measures, such as indoor residual spraying and personal protection, should be prioritized.
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Teorema de Bayes , Clima , Malaria Falciparum , Malaria Vivax , Análisis Espacio-Temporal , Laos/epidemiología , Malaria Vivax/epidemiología , Malaria Vivax/prevención & control , Malaria Falciparum/epidemiología , Malaria Falciparum/prevención & control , Incidencia , Humanos , Plasmodium vivax/fisiología , Tiempo (Meteorología) , Erradicación de la Enfermedad/estadística & datos numéricosRESUMEN
BACKGROUND: The effects of a diverse spectrum of malaria interventions were evaluated through a deterministic Plasmodium vivax transmission model. This approach aimed to provide theoretical evidence of the performance of these interventions once implemented for achieving malaria elimination. METHODS: An integrated intervention portfolio, including mass drug administration, insecticide treatment, and untreated bed nets, was analyzed through modeling. Additionally, data-driven calibration was implemented to infer coverages that effectively reproduced historical malaria patterns in China from 1971 to 1983. RESULTS: MDA utilizing primaquine emerged as the most effective single intervention, achieving a 70% reduction in malaria incidence when implemented at full coverage. Furthermore, a strategic combination of MDA with primaquine, chloroquine, untreated bed nets, and seasonal insecticide treatments effectively eradicated malaria, attaining elimination at a coverage level of 70%. It was conclusively demonstrated that an integrated approach combining MDA and vector control measures is essential for the successful elimination of malaria. CONCLUSION: High coverage of mass drug administration with primaquine and chloroquine before transmission was the key driver of the malaria decline in China from 1971 to 1983. The best-fit intervention coverage combinations derived from calibration are provided as a reference for malaria control in other countries.
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Antimaláricos , Malaria Vivax , Malaria Vivax/prevención & control , Malaria Vivax/epidemiología , China/epidemiología , Humanos , Antimaláricos/uso terapéutico , Plasmodium vivax/efectos de los fármacos , Primaquina/uso terapéutico , Administración Masiva de Medicamentos , Cloroquina/uso terapéutico , Control de Mosquitos/métodosRESUMEN
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.
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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.
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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.
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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
Ethiopia has a plan to eliminate malaria in selected low-transmission districts by 2025. However, complex factors such as seasonality, focal heterogeneity, and coendemicity of Plasmodium vivax and Plasmodium falciparum, and asymptomatic cases, along with other factors, pose challenges. This longitudinal study assessed these dynamics and associated factors in three elimination-targeted settings in southern Ethiopia. The study included rural districts (Wonago and Yirgacheffe) and an urban setting (Dilla town) with 504 participants from 168 households per season. The study covered the peak and minor malaria transmission seasons and the dry season. Finger-prick blood was collected for microscopy, rapid diagnostic tests, and 18S-rRNA-based quantitative polymerase chain reaction (qPCR). During the dry season, P. vivax accounted for most infections (64.5%, 71/110) and symptomatic malaria (50.9%, 29/57), whereas P. falciparum dominated during the peak transmission season (45.7%, 42/92 infections and 58.1%, 25/43 of symptomatic cases). Treatment-seeking behavior was low, with 65.3% (143/219) of symptomatic individuals not seeking treatment. Dilla town had significantly higher infection prevalence (29.6%, 149/504, P <0.001) in all seasons compared with the rural sites. The incidence rate was 12/1,000 person-seasons by qPCR and 5/1,000 person-seasons by microscopy. Urban residents, those with low hemoglobin levels, nonuse of mosquito nets, and proximity to stagnant water had a significantly higher risk of infection (P <0.001). Tailored approaches are needed in elimination-targeted areas, focusing on urban settings, Plasmodium species, and strengthening community-level interventions for behavioral change and active case detection.
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Malaria Falciparum , Malaria Vivax , Plasmodium falciparum , Plasmodium vivax , Estaciones del Año , Humanos , Malaria Vivax/epidemiología , Etiopía/epidemiología , Malaria Falciparum/epidemiología , Malaria Falciparum/diagnóstico , Adolescente , Femenino , Adulto , Masculino , Niño , Plasmodium vivax/aislamiento & purificación , Plasmodium falciparum/aislamiento & purificación , Plasmodium falciparum/genética , Adulto Joven , Preescolar , Estudios Longitudinales , Persona de Mediana Edad , Prevalencia , Lactante , Población Urbana , Población RuralRESUMEN
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.
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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
Malaria is a public health problem and the cases diagnosed in the capital of Roraima, Brazil, show potential to characterize the burden of the disease in the state. This study aimed to describe the epidemiological, clinical, and laboratory aspects of malaria cases diagnosed in Boa Vista. For this purpose, a descriptive, cross-sectional study was conducted in two health units in the city, with individuals diagnosed and who agreed to respond the questionnaire. Of the total of 206 participants, characterized as men, mixed-race, and young, 96% (198) reported participating in illegal mining activity. Among the group of miners, 66% (131) came from other states of Brazil or other countries. The mines were mainly located in the Yanomami territory in Roraima. Plasmodium vivax infection occurred in 74% (153) of participants. In the miner's group, hospitalizations for severe malaria, previous malaria attacks, and delays in treatment after the onset of symptoms were reported. Although 73% (145) of miners reported knowing how malaria was transmitted, only 54% (107) used mosquito nets or repellents. The use of Artecom and chloroquine by miners is not for the complete treatment but only to relieve symptoms for returning to gold mines, highlighting the importance of molecular surveillance to antimalarial resistance. Indigenous peoples are considered vulnerable to malaria and miners promotes the increase of malaria in Roraima Indigenous Lands. Therefore, access to diagnosis and treatment in Indigenous areas invaded by miners is imperative to confront this disease that ravages Indigenous communities and threatens public health on a large scale to achieve the goal of eliminating malaria in the state.
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Minería , Humanos , Brasil/epidemiología , Masculino , Estudios Transversales , Adulto , Adulto Joven , Femenino , Adolescente , Persona de Mediana Edad , Malaria Vivax/epidemiología , Malaria Vivax/prevención & control , Malaria/epidemiología , Malaria/prevención & control , Indígenas Sudamericanos/estadística & datos numéricosRESUMEN
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: Malaria remains a global health challenge, particularly in Peru's Loreto region. Despite ongoing efforts, high infection rates and asymptomatic cases perpetuate transmission. The Peruvian Ministry of Health's "Zero Malaria Plan" targets elimination. This novel study combines microscopic, molecular, and serological techniques to assess transmission intensity, identify epidemiological risk factors, and characterize species-specific patterns across villages. The findings aim to inform targeted interventions and support broader malaria elimination efforts in line with the Zero Malaria Plan initiative. METHODS: A cross-sectional malaria survey was conducted in the Zungarococha community, comprising the villages Llanchama (LL), Ninarumi (NI), Puerto Almendra (PA), and Zungarococha (ZG), using microscopic, molecular, and serological techniques to evaluate malaria transmission intensity. Statistical analysis, including multivariate-adjusted analysis, seroprevalence curves, and spatial clustering analysis, were performed to assess malaria prevalence, exposure, and risk factors. RESULTS: The survey revealed a high prevalence of asymptomatic infections (6% by microscopy and 18% by PCR), indicating that molecular methods are more sensitive for detecting asymptomatic infections. Seroprevalence varied significantly between villages, reflecting the heterogeneous malaria transmission dynamics. Multivariate analysis identified age, village, and limited bed net use as significant risk factors for malaria infection and species-specific exposure. Seroprevalence curves demonstrated community-specific patterns, with Llanchama and Puerto Almendra showing the highest seroconversion rates for both Plasmodium species. CONCLUSIONS: The study highlights the diverse nature of malaria transmission in the Loreto region, particularly nothing the pronounced heterogeneity as transmission rates decline, especially in residual malaria scenarios. The use of molecular and serological techniques enhances the detection of current infections and past exposure, aiding in the identification of epidemiological risk factors. These findings underscore the importance of using molecular and serological tools to characterize malaria transmission patterns in low-endemic areas, which is crucial for planning and implementing targeted interventions and elimination strategies. This is particularly relevant for initiatives like the Zero Malaria Plan in the Peruvian Amazon.