Challenges and opportunities in controlling mosquito-borne infections

Ferguson, Neil

doi:10.1038/s41586-018-0318-5

Cited by 126 publications

(105 citation statements)

References 92 publications

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“…Several important vector-borne NTDs have been targeted for elimination as a public-health problem by 2020 within the WHO NTD roadmap (4). Unfortunately, however, the burden of numerous VBDs will continue beyond the ambitious 2020 target (36–38). As evident within the WHO roadmap, both disease and vector surveillance form large components of most elimination strategies; however, the Strategic and Technical Advisory Group (STAG) for NTDs also recognise the need for a better understanding of the economic aspects of NTD control.…”

Section: Discussionmentioning

confidence: 99%

Quantifying geographic accessibility to improve efficiency of entomological monitoring

Longbottom

Krause

Torr

et al. 2019

Preprint

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AbstractBackgroundVector-borne diseases are important causes of mortality and morbidity in humans and livestock, particularly for poorer communities and countries in the tropics. Large-scale programs against these diseases, for example malaria, dengue and African trypanosomiasis, include vector control, and assessing the impact of this intervention requires frequent and extensive monitoring of disease vector abundance. Such monitoring can be expensive, especially in the later stages of a successful program where numbers of vectors and cases are low.Methodology/Principal FindingsWe developed a system that allows the identification of monitoring sites where pre-intervention densities of vectors are predicted to be high, and travel cost to sites is low, highlighting the most efficient locations for longitudinal monitoring. Using remotely sensed imagery and an image classification algorithm, we mapped landscape resistance associated with on- and off-road travel for every gridded location (3m and 0.5m grid cells) within Koboko district, Uganda. We combine the accessibility surface with pre-existing estimates of tsetse abundance and propose a stratified sampling approach to determine the most efficient locations for longitudinal data collection. Our modelled predictions were validated against empirical measurements of travel-time and existing maps of road networks. We applied this approach in northern Uganda where a large-scale vector control program is being implemented to control human African trypanosomiasis, a neglected tropical disease (NTD) caused by trypanosomes transmitted by tsetse flies. Our accessibility surfaces indicate a high performance when compared to empirical data, with remote sensing identifying a further ~70% of roads than existing networks.Conclusions/SignificanceBy integrating such estimates with predictions of tsetse abundance, we propose a methodology to determine the optimal placement of sentinel monitoring sites for evaluating control programme efficacy, moving from a nuanced, ad-hoc approach incorporating intuition, knowledge of vector ecology and local knowledge of geographic accessibility, to a reproducible, quantifiable one.Author SummaryAssessing the impact of vector control programmes requires longitudinal measurements of the abundance of insect vectors within intervention areas. Such monitoring can be expensive, especially in the later stages of a successful program where numbers of vectors and cases of disease are low. Efficient monitoring involves a prior selection of monitoring sites that are easy to reach and produce rich information on vector abundance. Here, we used image classification and cost-distance algorithms to produce estimates of accessibility within Koboko district, Uganda, where vector control is contributing to the elimination of sleeping sickness, a neglected tropical disease (NTD). We combine an accessibility surface with pre-existing estimates of tsetse abundance and propose a stratified sampling approach to determine locations which are associated with low cost (lowest travel time) and potential for longitudinal data collection (high pre-intervention abundance). Our method could be adapted for use in the planning and monitoring of tsetse- and other vector-control programmes. By providing methods to ensure that vector control programmes operate at maximum efficiency, we can ensure that the limited funding associated with some of these NTDs has the largest impact.

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Section: Discussionmentioning

confidence: 99%

Quantifying geographic accessibility to improve efficiency of entomological monitoring

Longbottom

Krause

Torr

et al. 2019

Preprint

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“…Such a bias would have to have a systematic spatial or temporal dependence in order to impact results; thus we deem the assumption that such a bias would not affect the results fair. Further, while we consistently observe a short-term positive impact of IRS on dengue incidence, we were unable to assess the longer-term impact of the containment activities and we cannot rule out these containment activities simply delay infection to future time points [28].…”

Section: Discussionmentioning

confidence: 99%

Quantifying the impact of dengue containment activities using high-resolution observational data

Rehman

Salje

Kraemer

et al. 2018

Preprint

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Dengue virus causes over 96 million cases worldwide per year and is expanding rapidly in geographic range, especially in urban areas. Containment activities are an essential part of reducing the public health burden caused by dengue, but systematic evidence on the comparative efficacy of activities from the field is lacking. To our knowledge, the effect of containment activities on local (sub-city) scale disease dynamics has never been systematically characterized using empirical containment and case data. We combine data from a comprehensive dengue containment monitoring system with confirmed dengue case data from the local government hospitals to estimate the efficacy of seven common containment activities in two urban areas in Pakistan. We use a modified version of the time series Suspected Infected Recovered framework to estimate how the reproductive number, R 0 , of the outbreak changed in relation to deployment of each containment activity. We also estimate the spatial dependence of cases based on deployment of each containment activity. Both analyses suggest that activities aimed at the adult phase of the mosquito lifecycle have the highest efficacy, with fogging having the largest quantifiable effect in reducing cases immediately after deployment. In examining the efficacy of containment activities contemporaneously deployed in the same locations, results here can guide recommendations for future deployment of resources during dengue outbreaks in urban settings.Dengue is a global threat; rapidly spreading with more than one half 2 of the world's population at risk for infection [1, 2]. Dengue virus is the 3 most ubiquitous human arbovirus. It is transmitted primarily by Aedes ae-4 gypti mosquitoes, a vector which also transmits several other global threats 5 including Zika, chikungunya and yellow fever [3]. Today, severe dengue is 6 a leading cause of hospitalization and death among children and adults in 7 urban areas in Asia, and Central and South America [4]. Dengue dispro-8 portionately affects urban areas in developing countries, which often have 9 limited resources for containment and intervention activities [5, 6]. 10To date, the most common approach to reducing the burden of dengue 11 is through prevention and containment of the vector population [7, 8]. Con-12 tainment activities focused on vector control broadly fall into three cate-13 gories: (i) activities targeted at reducing mosquito breeding sites (source 14 reduction); (ii) activities targeted at the larval stage of the vector; and (iii) 15 activities targeted at the adult stage of the vector [9]. While recent work 16 has advanced efforts such as vaccines, genetically modified mosquitoes and 17 Wolbachia-infected mosquitoes [10], these interventions are generally seen as 18 a complement to containment activities [11], and may be prohibitively costly 19 for many countries [12]. 20 Despite the widespread use of containment activities, costing millions of 21 dollars each year, the evidence base of how these activities reduce dengue 22 risk is...

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“…The overuse of chemical insecticides in recent years has raised resistance to various insecticide molecules in mosquito populations (Karunaratne et al ., ). This development encouraged the use of other alternative control methods whose success is based on a better knowledge of mosquito biology (Ferguson, ).…”

Section: Introductionmentioning

confidence: 99%

Who is eating fructose within the Aedes albopictus gut microbiota?

Guégan

Van

Martin

et al. 2020

Environmental Microbiology

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Summary The Asian tiger mosquito Aedes albopictus is a major public health concern because of its invasive success and its ability to transmit pathogens. Given the low availability of treatments against mosquito‐borne diseases, vector control remains the most suitable strategy. The methods used thus far are becoming less effective, but recent strategies have emerged from the study of mosquito‐associated microorganisms. Although the role of the microbiota in insect biology does not require further proof, much remains to be deciphered in mosquitoes, especially the contribution of the microbiota to host nutrient metabolism. Mosquitoes feed on plant nectar, composed of mostly fructose. We used stable isotope probing to identify bacteria and fungi assimilating fructose within the gut of Ae. albopictus. Mosquitoes were fed a 13C‐labelled fructose solution for 24 h. Differences in the active microbial community according to the sex of mosquitoes were highlighted. The bacterium Lelliottia and the fungi Cladosporium and Aspergillus dominated the active microbiota in males, whereas the bacterium Ampullimonas and the yeast Cyberlindnera were the most active in females. This study is the first to investigate trophic interactions between Ae. albopictus and its microbiota, thus underscoring the importance of the microbial component in nectar feeding in mosquitoes.

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Challenges and opportunities in controlling mosquito-borne infections

Cited by 126 publications

References 92 publications

Quantifying geographic accessibility to improve efficiency of entomological monitoring

Quantifying geographic accessibility to improve efficiency of entomological monitoring

Quantifying the impact of dengue containment activities using high-resolution observational data

Who is eating fructose within the Aedes albopictus gut microbiota?

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