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Open accessJournal ArticleDOI: 10.1371/JOURNAL.PONE.0247803

Real-time dispersal of malaria vectors in rural Africa monitored with lidar

04 Mar 2021-PLOS ONE (Public Library of Science)-Vol. 16, Iss: 3
Abstract: Lack of tools for detailed, real-time observation of mosquito behavior with high spatio-temporal resolution limits progress towards improved malaria vector control. We deployed a high-resolution entomological lidar to monitor a half-kilometer static transect positioned over rice fields outside a Tanzanian village. A quarter of a million in situ insect observations were classified, and several insect taxa were identified based on their modulation signatures. We observed distinct range distributions of male and female mosquitoes in relation to the village periphery, and spatio-temporal behavioral features, such as swarming. Furthermore, we observed that the spatial distributions of males and females change independently of each other during the day, and were able to estimate the daily dispersal of mosquitoes towards and away from the village. The findings of this study demonstrate how lidar-based monitoring could dramatically improve our understanding of malaria vector ecology and control options.

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Open accessJournal ArticleDOI: 10.1038/S41598-020-78021-X
Yared Debebe1, Sharon R. Hill2, Habte Tekie1, Sisay Dugassa1  +2 moreInstitutions (3)
08 Dec 2020-Scientific Reports
Abstract: Hotspots constitute the major reservoir for residual malaria transmission, with higher malaria incidence than neighbouring areas, and therefore, have the potential to form the cornerstone for successful intervention strategies. Detection of malaria hotspots is hampered by their heterogenous spatial distribution, and the laborious nature and low sensitivity of the current methods used to assess transmission intensity. We adopt ecological theory underlying foraging in herbivorous insects to vector mosquito host seeking and modelling of fine-scale landscape features at the village level. The overall effect of environmental variables on the density of indoor mosquitoes, sporozoite infected mosquitoes, and malaria incidence, was determined using generalized linear models. Spatial analyses were used to identify hotspots for malaria incidence, as well as malaria vector density and associated sporozoite prevalence. We identify household occupancy and location as the main predictors of vector density, entomological inoculation rate and malaria incidence. We propose that the use of conventional vector control and malaria interventions, integrated with their intensified application targeting predicted hotspots, can be used to reduce malaria incidence in endemic and residual malaria settings.

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Topics: Malaria (58%), Vector (epidemiology) (51%)

3 Citations


Open accessJournal ArticleDOI: 10.1109/JSTQE.2021.3062088
Abstract: Minimizing insecticide use, preventing vector diseases and facilitating biodiversity assessments are suitable applications of recent advances in photonic insect surveillance and entomological lidar. The tools also comprise a new window into fundamental aspect of the fascinating life and ecology of insects and their predators in situ . At the same time, it is evident that lidars are subject to finite detection range given by the instrument noise and saturation levels, and therefore, intervals of the biomass spectra are sectioned at different ranges. The Scheimpflug lidar allows an interesting trade-off between high sample rate and low pulse energy for retrieving wing beat harmonics and slow sample rates with high pulse energy for detecting small species far away. In this paper, we review and revise calibration, sizing and associated deficiencies, and report count rates to 104 insects/minute up to 2 km range. We investigate if and how high dynamic range can be exploited in entomological lidar and also how fast and slow sample rates could complement each other and capture a wider span of the biomass spectrum. We demonstrate that smaller insect can be detected further away by long exposures and show consistency between the captured biomass size spectra. However, we find unexpected discrepancies between short and long exposures in the range distributions. We found that vertebrates as well as specular insects can saturate signals. Error sources and limitations are elaborated on.

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Topics: Lidar (51%)

Proceedings ArticleDOI: 10.1109/ICLO48556.2020.9285848
02 Nov 2020-
Abstract: Here we present recent advances and applications of profiling biological targets with Scheimpflug lidar. In particular we demonstrate applications for profiling the aerofauna and classifying various groups of species. Based on lidar data over the Ivorian countryside we investigate range dependent detection limits by comparing data with distinct sample rates and pulse energies.

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Topics: Lidar (53%)

Open accessPosted Content
Abstract: Insect monitoring is critical to improve our understanding and ability to preserve and restore biodiversity, sustainably produce crops, and reduce vectors of human and livestock disease. However, conventional monitoring methods of trapping and identification are time consuming and thus expensive. Here, we present a network of distributed wireless sensors, recording backscattered near-infrared modulation signatures from insects. The instrument is a compact sensor based on dual-wavelength infrared light emitting diodes and is capable of unsupervised, autonomous long-term insect monitoring over weather and seasons. The sensor records the backscattered light at kHz pace from each insect transiting the measurement volume. Insect observations are automatically extracted and transmitted with environmental metadata over cellular connection to a cloud-based database. The recorded features include wing beat harmonics, melanisation and flight direction. To validate the sensor's capabilities, we tested the correlation between daily insect counts from an oil seed rape field measured with six yellow water traps and six sensors during a 4-week period. A comparison of the methods found a Spearman's rank correlation coefficient of 0.61 and a p-value of 0.0065, with the sensors recording approximately 19 times more insect observations and demonstrating a larger temporal dynamic than conventional trapping.

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Open accessJournal ArticleDOI: 10.1371/JOURNAL.PONE.0260167
18 Nov 2021-PLOS ONE
Abstract: Although small in size, insects are a quintessential part of terrestrial ecosystems due to their large number and diversity. While captured insects can be thoroughly studied in laboratory conditions, their population dynamics and abundance in the wild remain largely unknown due to the lack of accurate methodologies to count them. Here, we present the results of a field experiment where the activity of insects has been monitored continuously over 3 months using an entomological stand-off optical sensor (ESOS). Because its near-infrared laser is imperceptible to insects, the instrument provides an unbiased and absolute measurement of the aerial density (flying insect/m3) with a temporal resolution down to the minute. Multiple clusters of insects are differentiated based on their wingbeat frequency and ratios between wing and body optical cross-sections. The collected data allowed for the study of the circadian rhythm and daily activities as well as the aerial density dynamic over the whole campaign for each cluster individually. These measurements have been compared with traps for validation of this new methodology. We believe that this new type of data can unlock many of the current limitations in the collection of entomological data, especially when studying the population dynamics of insects with large impacts on our society, such as pollinators or vectors of infectious diseases.

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Topics: Population (52%)

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52 results found


Open access
01 Jan 2005-
Topics: Malaria (68%), Indoor residual spraying (55%)

4,964 Citations


Journal ArticleDOI: 10.1038/415680A
07 Feb 2002-Nature
Abstract: Where malaria prospers most, human societies have prospered least. The global distribution of per-capita gross domestic product shows a striking correlation between malaria and poverty, and malaria-endemic countries also have lower rates of economic growth. There are multiple channels by which malaria impedes development, including effects on fertility, population growth, saving and investment, worker productivity, absenteeism, premature mortality and medical costs.

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Topics: Malaria (55%), Poverty (52%), Population growth (51%) ... read more

2,229 Citations


Open accessJournal ArticleDOI: 10.1038/NATURE15535
Samir Bhatt1, Daniel J. Weiss1, Ewan Cameron1, Donal Bisanzio1  +28 moreInstitutions (11)
08 Oct 2015-Nature
Abstract: Since the year 2000, a concerted campaign against malaria has led to unprecedented levels of intervention coverage across sub-Saharan Africa. Understanding the effect of this control effort is vital to inform future control planning. However, the effect of malaria interventions across the varied epidemiological settings of Africa remains poorly understood owing to the absence of reliable surveillance data and the simplistic approaches underlying current disease estimates. Here we link a large database of malaria field surveys with detailed reconstructions of changing intervention coverage to directly evaluate trends from 2000 to 2015, and quantify the attributable effect of malaria disease control efforts. We found that Plasmodium falciparum infection prevalence in endemic Africa halved and the incidence of clinical disease fell by 40% between 2000 and 2015. We estimate that interventions have averted 663 (542-753 credible interval) million clinical cases since 2000. Insecticide-treated nets, the most widespread intervention, were by far the largest contributor (68% of cases averted). Although still below target levels, current malaria interventions have substantially reduced malaria disease incidence across the continent. Increasing access to these interventions, and maintaining their effectiveness in the face of insecticide and drug resistance, should form a cornerstone of post-2015 control strategies.

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Topics: Malaria (59%), Indoor residual spraying (54%)

1,647 Citations


Journal ArticleDOI: 10.1016/S0140-6736(12)60034-8
04 Feb 2012-The Lancet
Abstract: Summary Background During the past decade, renewed global and national efforts to combat malaria have led to ambitious goals. We aimed to provide an accurate assessment of the levels and time trends in malaria mortality to aid assessment of progress towards these goals and the focusing of future efforts. Methods We systematically collected all available data for malaria mortality for the period 1980–2010, correcting for misclassification bias. We developed a range of predictive models, including ensemble models, to estimate malaria mortality with uncertainty by age, sex, country, and year. We used key predictors of malaria mortality such as Plasmodium falciparum parasite prevalence, first-line antimalarial drug resistance, and vector control. We used out-of-sample predictive validity to select the final model. Findings Global malaria deaths increased from 995 000 (95% uncertainty interval 711 000–1 412 000) in 1980 to a peak of 1 817 000 (1 430 000–2 366 000) in 2004, decreasing to 1 238 000 (929 000–1 685 000) in 2010. In Africa, malaria deaths increased from 493 000 (290 000–747 000) in 1980 to 1 613 000 (1 243 000–2 145 000) in 2004, decreasing by about 30% to 1 133 000 (848 000–1 591 000) in 2010. Outside of Africa, malaria deaths have steadily decreased from 502 000 (322 000–833 000) in 1980 to 104 000 (45 000–191 000) in 2010. We estimated more deaths in individuals aged 5 years or older than has been estimated in previous studies: 435 000 (307 000–658 000) deaths in Africa and 89 000 (33 000–177 000) deaths outside of Africa in 2010. Interpretation Our findings show that the malaria mortality burden is larger than previously estimated, especially in adults. There has been a rapid decrease in malaria mortality in Africa because of the scaling up of control activities supported by international donors. Donor support, however, needs to be increased if malaria elimination and eradication and broader health and development goals are to be met. Funding The Bill & Melinda Gates Foundation.

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Topics: Malaria (61%), Child mortality (56%), Global health (53%)

1,398 Citations


Open accessBook
21 Dec 2007-
Abstract: Designing a Mosquito Sampling Programme- Sampling the Egg Population- Sampling the Larval Population- Sampling the Emerging Adult Population- Sampling the Adult Resting Population- Sampling Adults by Animal Bait Catches and by Animal-Baited Traps- Blood-feeding and its Epidemiological Significance- Sampling Adults with Non-attractant Traps- Sampling Adults with Light-Traps- Sampling Adults with Carbon Dioxide Traps- Sampling Adults with Visual Attraction Traps, Sound Traps and Other Miscellaneous Attraction Traps- Estimation of the Mortalities of the Immature Stages- Methods of Age-grading Adults and Estimation of Adult Survival Rates- Estimating the size of the Adult Population- Measuring Adult Dispersal- Experimental Hut Techniques- Indices of Association and Species Diversity Indices

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Topics: Sampling (statistics) (62%), Population (55%)

952 Citations


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