Subtle changes in Plasmodium falciparum infection complexity following enhanced intervention in Malawi

Sisya, Tamika J.; Kamng’ona, Raphael; Vareta, Jimmy; Fulakeza, Joseph; Mukaka, Mavuto; Seydel, Karl B.; Laufer, Miriam K.; Taylor, Terrie E.; Nkhoma, Standwell C.

doi:10.1016/j.actatropica.2014.11.008

Cited by 30 publications

(32 citation statements)

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“…Similar findings have been reported from the highlands in western Kenya and Malawi (Sisya et al, 2015;Zhong et al, 2007), in contrast to the low genetic diversity and high genetic differentiation that has been observed in low transmission settings in parts of Asia and South America (Anderson et al, 2000). Changes in H E occur slowly over time, and recent changes in malaria transmission combined with small sample sizes may therefore not provide the means to detect subtle changes in H E as a measure of genetic diversity (Sisya et al, 2015). Artesunate-amodiaquine was deployed as a first-line treatment for uncomplicated malaria in all public health facilities in 2003.…”

Section: Discussionsupporting

confidence: 89%

“…F ST analysis showed no detectable reduction in the effective population size or bottlenecks during the transition from high to low transmission in Zanzibar. Similar findings have been reported from the highlands in western Kenya and Malawi (Sisya et al, 2015;Zhong et al, 2007), in contrast to the low genetic diversity and high genetic differentiation that has been observed in low transmission settings in parts of Asia and South America (Anderson et al, 2000). Changes in H E occur slowly over time, and recent changes in malaria transmission combined with small sample sizes may therefore not provide the means to detect subtle changes in H E as a measure of genetic diversity (Sisya et al, 2015).…”

Section: Discussionmentioning

confidence: 54%

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Characterising temporal trends in asymptomatic Plasmodium infections and transporter polymorphisms during transition from high to low transmission in Zanzibar, 2005–2013

Morris

Msellem

et al. 2015

Infection, Genetics and Evolution

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 54%

Characterising temporal trends in asymptomatic Plasmodium infections and transporter polymorphisms during transition from high to low transmission in Zanzibar, 2005–2013

Morris

Msellem

et al. 2015

Infection, Genetics and Evolution

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“…Twelve or more loci were typed for 94 samples (see “Results” section). These loci and the SNP-genotyping protocol used have been termed a P. falciparum “molecular barcode” and are described elsewhere [18, 23, 29, 30]. The loci are distributed on 12 of the 14 P. falciparum chromosomes (see Additional file 1: Table S1) and are identical to those of Daniels et al [23].…”

Section: Methodsmentioning

confidence: 99%

Genetic evidence that the Makira region in northeastern Madagascar is a hotspot of malaria transmission

Rice

Golden

Anjaranirina

et al. 2016

Malar J

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BackgroundEncouraging advances in the control of Plasmodium falciparum malaria have been observed across much of Africa in the past decade. However, regions of high relative prevalence and transmission that remain unaddressed or unrecognized provide a threat to this progress. Difficulties in identifying such localized hotspots include inadequate surveillance, especially in remote regions, and the cost and labor needed to produce direct estimates of transmission. Genetic data can provide a much-needed alternative to such empirical estimates, as the pattern of genetic variation within malaria parasite populations is indicative of the level of local transmission. Here, genetic data were used to provide the first empirical estimates of P. falciparum malaria prevalence and transmission dynamics for the rural, remote Makira region of northeastern Madagascar.MethodsLongitudinal surveys of a cohort of 698 total individuals (both sexes, 0–74 years of age) were performed in two communities bordering the Makira Natural Park protected area. Rapid diagnostic tests, with confirmation by molecular methods, were used to estimate P. falciparum prevalence at three seasonal time points separated by 4-month intervals. Genomic loci in a panel of polymorphic, putatively neutral markers were genotyped for 94 P. falciparum infections and used to characterize genetic parameters known to correlate with transmission levels.ResultsOverall, 27.8% of individuals tested positive for P. falciparum over the 10-month course of the study, a rate approximately sevenfold higher than the countrywide average for Madagascar. Among those P. falciparum infections, a high level of genotypic diversity and a high frequency of polygenomic infections (68.1%) were observed, providing a pattern consistent with high and stable transmission.ConclusionsPrevalence and genetic diversity data indicate that the Makira region is a hotspot of P. falciparum transmission in Madagascar. This suggests that the area should be highlighted for future interventions and that additional areas of high transmission may be present in ecologically similar regions nearby.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1644-4) contains supplementary material, which is available to authorized users.

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“…The two most commonly used approaches, relatively small SNP barcodes and panels of microsatellite markers [38], have been extensively used to monitor changes in the diversity and structure of the parasite population. However, signals in these markers may not be sufficient to distinguish geographic origin, and they have limited resolution in certain transmission settings [39,40]. Increasing the discrimination of each locus will be necessary, and probably more effective than sequencing additional loci, for questions relevant to elimination.…”

Section: Current Sequencing Strategies For Genomic Epidemiology Of Mamentioning

confidence: 99%

Mapping malaria by combining parasite genomic and epidemiologic data

Wesolowski

Taylor

Chang

et al. 2018

Preprint

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Recent global progress in scaling up malaria control interventions has revived the goal of complete elimination in many countries. Decreasing transmission intensity generally leads to increasingly patchy spatial patterns of malaria transmission, however, and control programs must accurately identify remaining foci in order to target interventions efficiently. In particular, mosquito control interventions like bed nets and insecticide spraying are best targeted to transmission hotspots, and the role of connectivity between different pockets of local transmission becomes increasingly important since humans are able to move parasites beyond the limits of mosquito dispersal and re-introduce parasites to previously malaria-free regions. Quantifying the connectivity between regions due to human travel, measuring malaria transmission intensity in different areas, and monitoring parasite spatial spread are therefore key issues for policy-makers because they underpin the feasibility of elimination and inform the path to its attainment. To this end, recent efforts have been made to develop new approaches to incorporating human mobility into spatial epidemiological models, for example using mobile phone data, and there has been a surge of interest in collecting spatially informative parasite samples to measure the genomic signatures of parasite connectivity. Due to their complicated life-cycles, Plasmodium parasites pose unique challenges to researchers in this respect and new methods that move beyond traditional phylogenetic and population genetic tools must be All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/288506 doi: bioRxiv preprint first posted online Mar. 26, 2018; developed to harness genetic information effectively. Here, we discuss the spatial epidemiology of malaria in the context of transmission-reduction interventions, and the challenges and promising directions for the development of integrated mapping, modeling, and genomic approaches that leverage disparate data sets to measure both connectivity and transmission.All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/288506 doi: bioRxiv preprint first posted online Mar. 26, 2018; Main TextThe spatial dimensions of malaria control and elimination strategies Assessing variation in the spatial and temporal distribution of infection, or in the distribution of a particular pathogen phenotype like drug resistance, is an important prerequisite for any infectious disease control effort. For malaria, these considerations are critical across the range of transmission settings (Figure 1). In pre-elimination settings for example (e.g. E-2020 countries including Swazilan...

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Subtle changes in Plasmodium falciparum infection complexity following enhanced intervention in Malawi

Abstract: Graphical abstract

Cited by 30 publications

References 32 publications

Characterising temporal trends in asymptomatic Plasmodium infections and transporter polymorphisms during transition from high to low transmission in Zanzibar, 2005–2013

Characterising temporal trends in asymptomatic Plasmodium infections and transporter polymorphisms during transition from high to low transmission in Zanzibar, 2005–2013

Genetic evidence that the Makira region in northeastern Madagascar is a hotspot of malaria transmission

Mapping malaria by combining parasite genomic and epidemiologic data

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