Spatio-temporal trends of malaria incidence from 2011 to 2017 and environmental predictors of malaria transmission in Myanmar

Zhao, Yan; Aung, Pyae Linn; Ruan, Shishao; Win, Kyawt Mon; Wu, Zifang; Soe, Than Naing; Soe, Myat Thu; Cao, Yaming; Sattabongkot, Jetsumon; Kyaw, Myat Phone; Menezes, Lynette; Parker, Daniel M.

doi:10.1186/s40249-023-01055-6

Cited by 4 publications

(2 citation statements)

References 48 publications

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“…vivax samples from western Myanmar showed significantly higher COI than in northeastern Myanmar, reflecting higher P . vivax transmission intensity in western Myanmar, as we previously noted [ 64 ]. A notable observation from the analysis of longitudinal samples from northeast Myanmar is the significantly increased proportions of monoclonal infections from 2011 to 2018, which may reflect the more extensive control efforts delivered to this region.…”

Section: Discussionsupporting

confidence: 74%

Plasmodium vivax populations in the western Greater Mekong Subregion evaluated using a genetic barcode

Hu,

Li,

Brashear

et al. 2024

PLoS Negl Trop Dis

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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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Section: Discussionsupporting

confidence: 74%

Plasmodium vivax populations in the western Greater Mekong Subregion evaluated using a genetic barcode

Hu,

Li,

Brashear

et al. 2024

PLoS Negl Trop Dis

Self Cite

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“…In the GMS, studies based on aggregated surveillance data associated malaria transmission with forested areas [ 5 , 6 ]. Individual-scale studies consistently identified occupation-related risks factors, such as male sex, age over 15 years, or ‘going into the forest’ [ 7 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

‘Forest malaria’ in Myanmar? Tracking transmission landscapes in a diversity of environments

Legendre,

Girond,

Herbreteau

et al. 2023

Parasites Vectors

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Background In the Greater Mekong Subregion, case–control studies and national-level analyses have shown an association between malaria transmission and forest activities. The term ‘forest malaria’ hides the diversity of ecosystems in the GMS, which likely do not share a uniform malaria risk. To reach malaria elimination goals, it is crucial to document accurately (both spatially and temporally) the influence of environmental factors on malaria to improve resource allocation and policy planning within given areas. The aim of this ecological study is to characterize the association between malaria dynamics and detailed ecological environments determined at village level over a period of several years in Kayin State, Myanmar. Methods We characterized malaria incidence profiles at village scale based on intra- and inter-annual variations in amplitude, seasonality, and trend over 4 years (2016–2020). Environment was described independently of village localization by overlaying a 2-km hexagonal grid over the region. Specifically, hierarchical classification on principal components, using remote sensing data of high spatial resolution, was used to assign a landscape and a climate type to each grid cell. We used conditional inference trees and random forests to study the association between the malaria incidence profile of each village, climate and landscape. Finally, we constructed eco-epidemiological zones to stratify and map malaria risk in the region by summarizing incidence and environment association information. Results We identified a high diversity of landscapes (n = 19) corresponding to a gradient from pristine to highly anthropogenically modified landscapes. Within this diversity of landscapes, only three were associated with malaria-affected profiles. These landscapes were composed of a mosaic of dense and sparse forest fragmented by small agricultural patches. A single climate with moderate rainfall and a temperature range suitable for mosquito presence was also associated with malaria-affected profiles. Based on these environmental associations, we identified three eco-epidemiological zones marked by later persistence of Plasmodium falciparum, high Plasmodium vivax incidence after 2018, or a seasonality pattern in the rainy season. Conclusions The term forest malaria covers a multitude of contexts of malaria persistence, dynamics and populations at risk. Intervention planning and surveillance could benefit from consideration of the diversity of landscapes to focus on those specifically associated with malaria transmission. Graphical Abstract

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Global, regional, and national burden of malaria, 1990–2021: Findings from the global burden of disease study 2021

Zhang,

Yang,

Yang

et al. 2024

Decoding Infection and Transmission

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Spatio-temporal trends of malaria incidence from 2011 to 2017 and environmental predictors of malaria transmission in Myanmar

Cited by 4 publications

References 48 publications

Plasmodium vivax populations in the western Greater Mekong Subregion evaluated using a genetic barcode

Plasmodium vivax populations in the western Greater Mekong Subregion evaluated using a genetic barcode

‘Forest malaria’ in Myanmar? Tracking transmission landscapes in a diversity of environments

Global, regional, and national burden of malaria, 1990–2021: Findings from the global burden of disease study 2021

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