[Show abstract][Hide abstract] ABSTRACT: Background Major gains have been made in reducing malaria transmission in many parts of the world, principally by scaling-up coverage
with long-lasting insecticidal nets and indoor residual spraying. Historically, choice of vector control intervention has
been largely guided by a parameter sensitivity analysis of George Macdonald's theory of vectorial capacity that suggested
prioritizing methods that kill adult mosquitoes. While this advice has been highly successful for transmission suppression,
there is a need to revisit these arguments as policymakers in certain areas consider which combinations of interventions are
required to eliminate malaria.
Full-text · Article · Feb 2016 · Transactions of the Royal Society of Tropical Medicine and Hygiene
[Show abstract][Hide abstract] ABSTRACT: Rapid declines in malaria prevalence, cases, and deaths have been achieved globally during the past 15 years because of improved access to first-line treatment and vector control. We aimed to assess the intervention coverage needed to achieve further gains over the next 15 years.
Preview · Article · Jan 2016 · The Lancet Infectious Diseases
[Show abstract][Hide abstract] ABSTRACT: Major gains have been made in reducing malaria transmission in many parts of the world, principally by scaling-up coverage with long-lasting insecticidal nets and indoor residual spraying. Historically, choice of vector control intervention has been largely guided by a parameter sensitivity analysis of George Macdonald's theory of vectorial capacity that suggested prioritizing methods that kill adult mosquitoes. While this advice has been highly successful for transmission suppression, there is a need to revisit these arguments as policymakers in certain areas consider which combinations of interventions are required to eliminate malaria.
Using analytical solutions to updated equations for vectorial capacity we build on previous work to show that, while adult killing methods can be highly effective under many circumstances, other vector control methods are frequently required to fill effective coverage gaps. These can arise due to pre-existing or developing mosquito physiological and behavioral refractoriness but also due to additive changes in the relative importance of different vector species for transmission. Furthermore, the optimal combination of interventions will depend on the operational constraints and costs associated with reaching high coverage levels with each intervention.
Reaching specific policy goals, such as elimination, in defined contexts requires increasingly non-generic advice from modelling. Our results emphasize the importance of measuring baseline epidemiology, intervention coverage, vector ecology and program operational constraints in predicting expected outcomes with different combinations of interventions.
No preview · Article · Jan 2016 · Transactions of the Royal Society of Tropical Medicine and Hygiene
[Show abstract][Hide abstract] ABSTRACT: Aedes aegypti and Ae. albopictus are the main vectors transmitting dengue and chikungunya viruses. Despite being pathogens of global public health importance, knowledge of their vectors' global distribution remains patchy and sparse. A global geographic database of known occurrences of Ae. aegypti and Ae. albopictus between 1960 and 2014 was compiled. Herein we present the database, which comprises occurrence data linked to point or polygon locations, derived from peer-reviewed literature and unpublished studies including national entomological surveys and expert networks. We describe all data collection processes, as well as geo-positioning methods, database management and quality-control procedures. This is the first comprehensive global database of Ae. aegypti and Ae. albopictus occurrence, consisting of 19,930 and 22,137 geo-positioned occurrence records respectively. Both datasets can be used for a variety of mapping and spatial analyses of the vectors and, by inference, the diseases they transmit.
[Show abstract][Hide abstract] ABSTRACT: Figure 1 – figure supplement 2. Set of covariate layers used to predict the ecological niche of Ae. aegypti and Ae. albopictus described in detail in the Materials and Methods section; a) enhanced vegetation index (EVI) annual mean, b) EVI annual range, c) annual monthly maximum precipitation, d) annual monthly minimum precipitation, e) temperature suitability for Ae. albopictus, f) temperature suitability for Ae. aegypti, g) rural, peri-urban and urban classification layer.
[Show abstract][Hide abstract] ABSTRACT: Dengue and chikungunya are increasing global public health concerns due to their rapid geographical spread and increasing disease burden. Knowledge of the contemporary distribution of their shared vectors, Aedes aegypti and Ae. albopictus remains incomplete and is complicated by an ongoing range expansion fuelled by increased global trade and travel. Mapping the global distribution of these vectors and the geographical determinants of their ranges is essential for public health planning. Here we compile the largest contemporary database for both species and pair it with relevant environmental variables predicting their global distribution. We show Aedes distributions to be the widest ever recorded; now extensive in all continents, including North America and Europe. These maps will help define the spatial limits of current autochthonous transmission of dengue and chikungunya viruses. It is only with this kind of rigorous entomological baseline that we can hope to project future health impacts of these viruses.
- See more at: http://elifesciences.org/content/early/2015/06/29/eLife.08347/article-data#.dpuf
[Show abstract][Hide abstract] ABSTRACT: Figure 1 – figure supplement 4. The distribution of the occurrence database for Ae. aegypti (a) and Ae. albopictus (b) plotted on the underlying prediction surface.
[Show abstract][Hide abstract] ABSTRACT: Figure 1 – figure supplement 3. Visualization of pixel level uncertainty calculated using the upper and lower bounds of the 95% confidence intervals associated with the prediction maps for Ae. aegypti (a) and Ae. albopictus (b).
[Show abstract][Hide abstract] ABSTRACT: Figure 1 – figure supplement 1. Effect plots of covariates used in this study showing the marginal effect of each covariate on probability of presence for Ae. aegypti (1) and Ae. albopictus (2): Enhanced vegetation index - mean (a); Enhanced vegetation index - range (b); Maximum precipitation (c); Minimum precipitation (d); Temperature suitability (e); Urban areas (f); peri-urban areas (g).
[Show abstract][Hide abstract] ABSTRACT: Malaria remains one of the greatest human health burdens in Indonesia. Although Indonesia has a long and renowned history in the early research and discoveries of malaria and subsequently in the successful use of environmental control methods to combat the vector, much remains unknown about many of these mosquito species. There are also significant gaps in the existing knowledge on the transmission epidemiology of malaria, most notably in the highly malarious eastern half of the archipelago. These compound the difficulty of developing targeted and effective control measures. The sheer complexity and number of malaria vectors in the country are daunting. The difficult task of summarizing the available information for each species and/or species complex is compounded by the patchiness of the data: while relatively plentiful in one area or region, it can also be completely lacking in others. Compared to many other countries in the Oriental and Australasian biogeographical regions, only scant information on vector bionomics and response to chemical measures is available in Indonesia. That information is often either decades old, geographically patchy or completely lacking. Additionally, a large number of information sources are published in Dutch or Indonesian language and therefore less accessible. This review aims to present an updated overview of the known distribution and bionomics of the 20 confirmed malaria vector species or species complexes regarded as either primary or secondary (incidental) malaria vectors within Indonesia. This chapter is not an exhaustive review of each of these species. No attempt is made to specifically discuss or resolve the taxonomic record of listed species in this document, while recognizing the ever evolving revisions in the systematics of species groups and complexes. A review of past and current status of insecticide susceptibility of eight vector species of malaria is also provided.
Full-text · Article · Jul 2013 · Advances in Parasitology
[Show abstract][Hide abstract] ABSTRACT: Plasmodium vivax occurs globally and thrives in both temperate and tropical climates. Here, we review the evidence of the biological limits of its contemporary distribution and the global population at risk (PAR) of the disease within endemic countries. We also review the most recent evidence for the endemic level of transmission within its range and discuss the implications for burden of disease assessments. Finally, the evidence-base for defining the contemporary distribution and PAR of P. vivax are discussed alongside a description of the vectors of human malaria within the limits of risk. This information along with recent data documenting the severe morbid and fatal consequences of P. vivax infection indicates that the public health significance of P. vivax is likely to have been seriously underestimated.
Full-text · Article · Nov 2012 · Advances in Parasitology
[Show abstract][Hide abstract] ABSTRACT: Global maps, in particular those based on vector distributions, have long been used to help visualise the global extent of malaria. Few, however, have been created with the support of a comprehensive and extensive evidence-based approach.
Here we describe the generation of a global map of the dominant vector species (DVS) of malaria that makes use of predicted distribution maps for individual species or species complexes.
Our global map highlights the spatial variability in the complexity of the vector situation. In Africa, An. gambiae, An. arabiensis and An. funestus are co-dominant across much of the continent, whereas in the Asian-Pacific region there is a highly complex situation with multi-species coexistence and variable species dominance.
The competence of the mapping methodology to accurately portray DVS distributions is discussed. The comprehensive and contemporary database of species-specific spatial occurrence (currently available on request) will be made directly available via the Malaria Atlas Project (MAP) website from early 2012.
[Show abstract][Hide abstract] ABSTRACT: ABSTRACT: In our original publication detailing the distribution of the dominant vector species of malaria in the Americas (Sinka et al. Parasit Vectors 2010, 3: 72.), both Figure one (The predicted distribution map of An. darlingi) and the An. darlingi map shown in Additional file two (The predicted distribution maps of the nine dominant vector species of the Americas) included points on the border between Costa Rica and Nicaragua. These are confirmed absence points and therefore should not have been included. These maps are intended to indicate locations only where the species presence has been confirmed. Anopheles darlingi has never been found or reported from Costa Rica or Nicaragua (as indicated in the Expert opinion map) despite numerous and comprehensive surveys in the area trying to locate it. Copies of the corrected figure and the updated Additional file can be found in Figure 1 and Additional file 1 (in this publication) and are also available on the Malaria Atlas Project (MAP) website: Figure One: http://www.map.ox.ac.uk/media/PDF/Figure%201%20-%20An%20darlingi%20-%20corrected.png Additional File Two (all species maps): http://www.map.ox.ac.uk/media/PDF/Sinka%20et%20al_Additional%20file%202%20-%20final%20maps%20(FINAL).pdf.
Full-text · Article · Nov 2011 · Parasites & Vectors
[Show abstract][Hide abstract] ABSTRACT: Additional file 2:
Summary tables showing evaluation statistics for all mapping trials and final Boosted Regression Tree environmental and climatic variable selections for the final, optimal predictive maps.
[Show abstract][Hide abstract] ABSTRACT: The final article in a series of three publications examining the global distribution of 41 dominant vector species (DVS) of malaria is presented here. The first publication examined the DVS from the Americas, with the second covering those species present in Africa, Europe and the Middle East. Here we discuss the 19 DVS of the Asian-Pacific region. This region experiences a high diversity of vector species, many occurring sympatrically, which, combined with the occurrence of a high number of species complexes and suspected species complexes, and behavioural plasticity of many of these major vectors, adds a level of entomological complexity not comparable elsewhere globally. To try and untangle the intricacy of the vectors of this region and to increase the effectiveness of vector control interventions, an understanding of the contemporary distribution of each species, combined with a synthesis of the current knowledge of their behaviour and ecology is needed.
Expert opinion (EO) range maps, created with the most up-to-date expert knowledge of each DVS distribution, were combined with a contemporary database of occurrence data and a suite of open access, environmental and climatic variables. Using the Boosted Regression Tree (BRT) modelling method, distribution maps of each DVS were produced. The occurrence data were abstracted from the formal, published literature, plus other relevant sources, resulting in the collation of DVS occurrence at 10116 locations across 31 countries, of which 8853 were successfully geo-referenced and 7430 were resolved to spatial areas that could be included in the BRT model. A detailed summary of the information on the bionomics of each species and species complex is also presented.
This article concludes a project aimed to establish the contemporary global distribution of the DVS of malaria. The three articles produced are intended as a detailed reference for scientists continuing research into the aspects of taxonomy, biology and ecology relevant to species-specific vector control. This research is particularly relevant to help unravel the complicated taxonomic status, ecology and epidemiology of the vectors of the Asia-Pacific region. All the occurrence data, predictive maps and EO-shape files generated during the production of these publications will be made available in the public domain. We hope that this will encourage data sharing to improve future iterations of the distribution maps.
Full-text · Article · May 2011 · Parasites & Vectors