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Javed N, Paradkar PN, Bhatti A. An overview of technologies available to monitor behaviours of mosquitoes. Acta Trop 2024; 258:107347. [PMID: 39103110 DOI: 10.1016/j.actatropica.2024.107347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Revised: 07/30/2024] [Accepted: 07/31/2024] [Indexed: 08/07/2024]
Abstract
Mosquito-borne diseases such as malaria, dengue, Zika, and chikungunya cause significant morbidity and mortality globally, resulting in over 600,000 deaths from malaria and around 36,000 deaths from dengue each year, with millions of people infected annually, leading to substantial economic losses. The existing mosquito control measures, such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), helped to reduce the infections. However, mosquito-borne diseases are still among the deadliest diseases, forcing us to improve the existing control methods and look for alternative methods simultaneously. Advanced monitoring techniques, including remote sensing, and geographic information systems (GIS) have significantly enhanced the efficiency and effectiveness of mosquito control measures. Mosquitoes' behavioural traits, such as locomotion, blood-feeding, and fertility are the key determinants of disease transmission and epidemiology. Technological advancements, such as high-resolution cameras, infrared imaging, and artificial intelligence (AI) driven object detection models, including groundbreaking convolutional neural networks, have provided efficient and precise options to monitor various mosquito behaviours, including locomotion, oviposition, fertility, and host-seeking. However, they are not commonly employed in mosquito-based research. This review highlights the novel and significant advancements in behaviour-monitoring tools, mostly from the last decade, due to cutting-edge video monitoring technology and artificial intelligence. These advancements can offer enhanced accuracy, efficiency, and the ability to quickly process large volumes of data, enabling detailed behavioural analysis over extended periods and large sample sizes, unlike traditional manual methods prone to human error and labour-intensive. The use of behaviour-assaying techniques can support or replace existing monitoring techniques and directly contribute to improving control measures by providing more accurate and real-time data on mosquito activity patterns and responses to interventions. This enhanced understanding can help establish the role of behavioural changes in improving epidemiological models, making them more precise and dynamic. As a result, mosquito management strategies can become more adaptive and responsive, leading to more effective and targeted interventions. Ultimately, this will reduce disease transmission and significantly improve public health outcomes.
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Affiliation(s)
- Nouman Javed
- Institute for Intelligent Systems Research and Innovation, Deakin University, Geelong, Victoria 3216 Australia.
| | - Prasad N Paradkar
- CSIRO Health & Biosecurity, Australian Centre for Disease Preparedness, Geelong, Victoria 3220 Australia
| | - Asim Bhatti
- Institute for Intelligent Systems Research and Innovation, Deakin University, Geelong, Victoria 3216 Australia
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Kambou SS, Valente A, Agnew P, Hien DFDS, Yerbanga RS, Moiroux N, Dabire KR, Pennetier C, Cohuet A, Carrasco D. Non-contact detection of pyrethroids widely used in vector control by Anopheles mosquitoes. PLoS One 2024; 19:e0298512. [PMID: 38995958 PMCID: PMC11244766 DOI: 10.1371/journal.pone.0298512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 06/19/2024] [Indexed: 07/14/2024] Open
Abstract
Pyrethroids are the most widely used insecticides to control vector borne diseases including malaria. Physiological resistance mechanisms to these insecticides have been well described, whereas those for behavioral resistance remain overlooked. Field data suggest the presence of spatial sensory detection by Anopheles mosquitoes of the pyrethroid molecules used in insecticide-based control tools, such as long-lasting insecticide nets or insecticide residual spraying. This opens the way to the emergence of a wide range of behavioral adaptations among malaria vectors. However, the spatial sensory detection of these molecules is controversial and needs to be demonstrated. The goal of this study was to behaviorally characterize the non-contact detection of three of the most common pyrethroids used for malaria vector control: permethrin, deltamethrin an ⍺-cypermethrin. To reach this goal, we recorded the behavior (takeoff response) of Anopheles gambiae pyrethroid-sensitive and resistant laboratory strains, as well as field collected mosquitoes from the Gambiae Complex, when exposed to the headspace of bottles containing different doses of the insecticides at 25 and 35°C, in order to represent a range of laboratory and field temperatures. We found the proportion of laboratory susceptible and resistant female mosquitoes that took off was, in all treatments, dose and the temperature dependent. Sensitive mosquitoes were significantly more prone to take off only in the presence of ⍺-cypermethrin, whereas sensitive and resistant mosquitoes showed similar responses to permethrin and deltamethrin. Field-collected mosquitoes of the Gambiae Complex were also responsive to permethrin, independently of the species identity (An. gambiae, An. coluzzii and An. arabiensis) or their genotypes for the kdr mutation, known to confer resistance to pyrethroids. The observed ability of Anopheles spp. mosquitoes to detect insecticides without contact could favor the evolution of behavioral modifications that may allow them to avoid or reduce the adverse effect of insecticides and thus, the development of behavioral resistance.
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Affiliation(s)
- Sassan Simplice Kambou
- MIVEGEC, University Montpellier, IRD, CNRS, Montpellier, France
- Institut de Recherche en Sciences de la Santé (IRSS), Centre National de Recherche Scientifique et Technique (CNRST), Bobo-Dioulasso, Burkina Faso
| | - Adeline Valente
- MIVEGEC, University Montpellier, IRD, CNRS, Montpellier, France
| | - Philip Agnew
- MIVEGEC, University Montpellier, IRD, CNRS, Montpellier, France
| | - Domonbabele François de Sales Hien
- Institut de Recherche en Sciences de la Santé (IRSS), Centre National de Recherche Scientifique et Technique (CNRST), Bobo-Dioulasso, Burkina Faso
| | - Rakiswendé Serge Yerbanga
- MIVEGEC, University Montpellier, IRD, CNRS, Montpellier, France
- Institut des Sciences et Techniques (InSTech), Bobo-Dioulasso, Burkina Faso
| | - Nicolas Moiroux
- MIVEGEC, University Montpellier, IRD, CNRS, Montpellier, France
| | - Kounbobr Roch Dabire
- Institut de Recherche en Sciences de la Santé (IRSS), Centre National de Recherche Scientifique et Technique (CNRST), Bobo-Dioulasso, Burkina Faso
| | | | - Anna Cohuet
- MIVEGEC, University Montpellier, IRD, CNRS, Montpellier, France
| | - David Carrasco
- MIVEGEC, University Montpellier, IRD, CNRS, Montpellier, France
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Fatou M, Müller P. 3D video tracking analysis reveals that mosquitoes pass more likely through holes in permethrin-treated than in untreated nets. Sci Rep 2024; 14:13598. [PMID: 38866869 PMCID: PMC11169678 DOI: 10.1038/s41598-024-63968-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 06/04/2024] [Indexed: 06/14/2024] Open
Abstract
In addition to killing, mosquito nets treated with permethrin have been claimed to repel mosquitoes, reducing their success in passing through a holed net. We have tested this hypothesis by tracking mosquitoes in a modified World Health Organization tunnel test. In the original assay, mosquitoes are released at one end of the tunnel and have to pass through a holed piece of net to reach the bait at the other end. The mosquitoes are left in the tunnel overnight, while mortality and feeding rates are scored the following morning. Since the original test does not reveal how mosquitoes move within the tunnel, we combined the tunnel with a 3D video camera system. We tracked susceptible and permethrin-resistant Anopheles gambiae s.s. as they moved in the tunnel and interacted with an untreated or a permethrin-treated net (Olyset Net®). Surprisingly, while permethrin increased the mortality and reduced blood-feeding rates, twice as many mosquitoes passed through the holes of the permethrin-treated net. The flight trajectories reveal that upon exposure to the permethrin-treated net, both mosquito colonies showed increased 'excitation', thereby augmenting their chance of getting through the holes in the net. The study underlines the complexity of behavioural modes of action of insecticides.
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Affiliation(s)
- Mathurin Fatou
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland.
| | - Pie Müller
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
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Parker JEA, Kakilla C, Nelwin K, Kroner C, Logan R, Ismail HM, Towers C, Manjurano A, Towers D, McCall PJ. Video-tracked Anopheles arabiensis entry and exit behaviour at washed and damaged pyrethroid-treated bednets. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231165. [PMID: 39076790 PMCID: PMC11285834 DOI: 10.1098/rsos.231165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 04/03/2024] [Accepted: 04/05/2024] [Indexed: 07/31/2024]
Abstract
Insecticide-treated nets (ITNs) are the most effective method for malaria prevention in Africa. Using near-infrared video tracking in a laboratory environment, we recorded and assessed bednet entry and exit by a northern Tanzanian population of Anopheles arabiensis at a human-occupied untreated net and a PermaNet® 2.0 ITN. Both had 12 holes, each 10 cm in diameter, punctured at specific locations, and the ITN was washed 20 times to further simulate the wear and tear of ageing. Washing reduced the insecticide content of ITNs by 61%, which then showed similar rates to the untreated nets for net entry (39% entered untreated net and 41% entered ITN; p = 0.84) and exit (37% and 43%, respectively; p = 0.67). Regardless of treatment, approximately 40% of mosquitoes entered nets within 20 s of first appearing in the field of view and reached the volunteer's skin within 5 s of entering the net. Mortality rates post-exposure were significantly higher (p = 0.048) at ITNs (26.6%; 95% CI 13.4%-39.7%) than at untreated controls (6.4%; 95% CI 1.8%-14.6%). The washed and aged ITN provided little additional personal protection for the sleeper over an untreated net. Simple adjustments to materials and design that could extend the effective lifespan of ITNs are discussed.
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Affiliation(s)
- J. E. A. Parker
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - C. Kakilla
- National Institute of Medical Research, Mwanza, Tanzania
| | - K. Nelwin
- National Institute of Medical Research, Mwanza, Tanzania
| | - C. Kroner
- School of Engineering, University of Warwick, Coventry, UK
| | - R. Logan
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- Parasitology Department, Heidelberg University Hospital, Heidelberg, Germany
| | - H. M. Ismail
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - C. Towers
- School of Engineering, University of Warwick, Coventry, UK
| | - A. Manjurano
- National Institute of Medical Research, Mwanza, Tanzania
| | - D. Towers
- School of Engineering, University of Warwick, Coventry, UK
| | - P. J. McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
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Feio-Dos-Santos AC, Reis CC, Sucupira IMC, Lenhart A, Santos MMM, Reis ER, do Carmo EL, Daniel S, Mesones Lapouble OM, de Oliveira AM, Povoa MM. Physical durability and insecticidal activity of long-lasting insecticidal nets in Cruzeiro do Sul, Brazil. Sci Rep 2024; 14:9044. [PMID: 38641670 PMCID: PMC11031583 DOI: 10.1038/s41598-024-59172-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 04/08/2024] [Indexed: 04/21/2024] Open
Abstract
Vector control is one of the principal strategies used for reducing malaria transmission. Long-lasting insecticidal bed nets (LLINs) are a key tool used to protect populations at risk of malaria, since they provide both physical and chemical barriers to prevent human-vector contact. This study aimed to assess the physical durability and insecticidal efficacy of LLINs distributed in Cruzeiro do Sul (CZS), Brazil, after 4 years of use. A total of 3000 LLINs (PermaNet 2.0) were distributed in high malaria risk areas of CZS in 2007. After 4 years of use, 27 'rectangular' LLINs and 28 'conical' LLINs were randomly selected for analysis. The evaluation of physical integrity was based on counting the number of holes and measuring their size and location on the nets. Insecticidal efficacy was evaluated by cone bioassays, and the amount of residual insecticide remaining on the surface of the LLINs was estimated using a colorimetric method. After 4 years of use, physical damage was highly prevalent on the rectangular LLINs, with a total of 473 holes detected across the 27 nets. The upper portion of the side panels sustained the greatest damage in rectangular LLINs. The overall mosquito mortality by cone bioassay was < 80% in 25/27 rectangular LLINs, with panel A (at the end of the rectangular bednet) presenting the highest mortality (54%). The overall mean insecticide concentration was 0.5 µg/sample, with the bednet roof containing the highest average concentration (0.61 µg/sample). On the conical LLINs, 547 holes were detected, with the bottom areas sustaining the greatest damage. The cone bioassay mortality was < 80% in 26/28 of the conical LLINs. The mean insecticide concentration was 0.3 µg/sample. After 4 years of use, the insecticidal efficacy of the LLINs was diminished to below acceptable thresholds.
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Affiliation(s)
- Ana Cecília Feio-Dos-Santos
- Pós-Graduação em Biologia de Agentes Infecciosos e Parasitários, Universidade Federal do Pará, Belém, Pará, 66075-110, Brazil
- Laboratório de Entomologia de Malária, Seção de Parasitologia, Instituto Evandro Chagas/SVSA/MS, Ananindeua, Pará, CEP 67030-000, Brazil
| | - Crissiane C Reis
- Pós-Graduação em Biologia de Agentes Infecciosos e Parasitários, Universidade Federal do Pará, Belém, Pará, 66075-110, Brazil
- Laboratório de Entomologia de Malária, Seção de Parasitologia, Instituto Evandro Chagas/SVSA/MS, Ananindeua, Pará, CEP 67030-000, Brazil
| | - Izis M C Sucupira
- Laboratório de Entomologia de Malária, Seção de Parasitologia, Instituto Evandro Chagas/SVSA/MS, Ananindeua, Pará, CEP 67030-000, Brazil.
| | - Audrey Lenhart
- Division of Parasitic Diseases and Malaria, Entomology Branch, Centers for Disease Control and Prevention (CDC), 1600 Clifton Road, Atlanta, GA, 30329, USA
| | - Márcia M M Santos
- Laboratório de Entomologia de Malária, Seção de Parasitologia, Instituto Evandro Chagas/SVSA/MS, Ananindeua, Pará, CEP 67030-000, Brazil
| | - Ediane R Reis
- Laboratório de Entomologia de Malária, Seção de Parasitologia, Instituto Evandro Chagas/SVSA/MS, Ananindeua, Pará, CEP 67030-000, Brazil
| | - Ediclei Lima do Carmo
- Seção de Parasitologia, Instituto Evandro Chagas/SVSA/MS, Ananindeua, Pará, CEP 67030-000, Brazil
| | - Simone Daniel
- Hospital Juruá, Av. 25 de Agosto, 2151, Cruzeiro do Sul, Acre, Brazil
| | - Oscar M Mesones Lapouble
- Pan American Health Organization/World Health Organization Office in Suriname, Henck Arronstraat #60, Paramaribo, Suriname
| | - Alexandre Macedo de Oliveira
- Division of Parasitic Diseases and Malaria, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Marinete M Povoa
- Pós-Graduação em Biologia de Agentes Infecciosos e Parasitários, Universidade Federal do Pará, Belém, Pará, 66075-110, Brazil
- Laboratório de Entomologia de Malária, Seção de Parasitologia, Instituto Evandro Chagas/SVSA/MS, Ananindeua, Pará, CEP 67030-000, Brazil
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Abbott AJ, Matope A, Jones J, Voloshin V, Towers CE, Towers D, McCall PJ. Insecticidal roof barriers mounted on untreated bed nets can be as effective against Anopheles gambiae as regular insecticide-treated bed nets. Sci Rep 2023; 13:22080. [PMID: 38086842 PMCID: PMC10716170 DOI: 10.1038/s41598-023-48499-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
Barrier bednets (BBnets), regular bednets with a vertical insecticidal panel to target mosquitoes above the bednet roof, where they are most active, have the potential to improve existing Insecticidal Treated Bednets (ITNs), by reducing the quantity of insecticide required per net, reducing the toxic risks to those using the net, potentially increasing insecticide choice. We evaluated the performance of PermaNet 3.0 (P3) and untreated (Ut) bed nets with and without pyrethroid and piperonyl butoxide roof barriers in killing pyrethroid-resistant and susceptible Anopheles gambiae, simultaneously video-recording mosquito flight tracks. Bioassay results showed that treated roof barriers, particularly the longitudinal P3 barrier (P3L) could be an effective addition to a bed net: P3 + P3L were consistently significantly more effective than the reference P3 bednet while performance of untreated nets could be raised to equal that of the reference P3 following the addition of a P3 barrier. The BBnet's potential to augment existing bednets and enhance their performance is considered.
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Affiliation(s)
- Anthony J Abbott
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Agnes Matope
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Jeff Jones
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Vitaly Voloshin
- Optical Engineering Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Catherine E Towers
- Optical Engineering Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - David Towers
- Optical Engineering Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Philip J McCall
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK.
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Jones J, Matope A, Barreaux P, Gleave K, Steen K, Ranson H, McCall PJ, Foster GM. Video augmentation of the WHO cone assay to quantify mosquito behavioural responses to insecticide-treated nets. Parasit Vectors 2023; 16:420. [PMID: 37968752 PMCID: PMC10652617 DOI: 10.1186/s13071-023-06029-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 10/20/2023] [Indexed: 11/17/2023] Open
Abstract
BACKGROUND Insecticide-treated nets (ITNs) using pyrethroids have been the main vector control tools deployed in malaria endemic countries and are responsible for the dramatic reduction in African malaria cases in the early 2000s. The World Health Organization (WHO) cone test was designed to assess the rapid toxicity effects of pyrethroid exposure on mosquito vectors but has yielded no insights beyond 60-min knockdown and 24-h mortality. As dual-active-ingredient (AI) ITNs become more widespread, bioassays that can provide realistic assessment of single- and dual-treated ITNs (i.e. nets with more than one active ingredient) are urgently needed. METHODS We present an augmentation of the cone test that enables accurate quantification of vector behavioural responses (specifically movement, spatial and temporal occupancy) to ITNs using video recording and bespoke software that uses background segmentation methods to detect spatial changes in the movement of mosquitoes within the cone. Four strains of Anopheles gambiae sensu lato (s.l.) were exposed to four ITNs (PermaNet 2.0, PermaNet 3.0, Olyset Net, Interceptor G2) and untreated nets in these modified cone tests. Life history data (post-exposure blood-feeding, blood meal weight, longevity) for individual mosquitoes were recorded. RESULTS All mosquitoes responded to the presence of ITNs, spending from 1.48 to 3.67 times more time in the upper region of the cone, depending on the ITN type. Of all ITNs, PermaNet 2.0 provoked the smallest change in behavioural response. Activity in the cone influenced observed post-exposure longevity, and in resistant strains exposed to Interceptor G2, the higher the activity, the greater the risk of dying, as long as the proportion of activity at the net surface was less than 50%. All ITNs inhibited blood-feeding, and smaller blood meals were taken when mosquitoes fed. CONCLUSIONS The additional mosquito behaviour data obtained by using this modification to the WHO cone test provides unique insight into the innate responses of different mosquito strains on untreated nets and the entomological mode of action of ITNs, important evidence when evaluating ITN characteristics.
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Affiliation(s)
- Jeff Jones
- Department of Vector Biology Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Agnes Matope
- Department of Vector Biology Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Priscille Barreaux
- Department of Vector Biology Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Katherine Gleave
- Department of Vector Biology Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Keith Steen
- Department of Vector Biology Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Hilary Ranson
- Department of Vector Biology Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Philip J McCall
- Department of Vector Biology Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Geraldine M Foster
- Department of Vector Biology Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.
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Kampango A, Smith TA, Abílio AP, Machoe EA, Matusse JF, Pinto J, McCall PJ. The Shockwè trap: a human-baited exposure-free device for surveillance and behaviour studies of anthropophilic vectors. Wellcome Open Res 2023; 8:455. [PMID: 38644931 PMCID: PMC11031644 DOI: 10.12688/wellcomeopenres.19963.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2023] [Indexed: 04/23/2024] Open
Abstract
Background: The human biting rate (MBR) and entomological inoculation rate (EIR) are common parameters routinely used to measure the risk of malaria transmission. Both parameters can be estimated using human landing catches (HLC). Although it is considered the gold-standard, HLC puts collectors at higher risk of infection with mosquito-transmitted pathogens. Methods: A novel exposure-free host-seeking mosquito electrocution trap, the Shockwè trap (SHK), was developed and its efficiency for monitoring mosquito community composition and abundance was compared with human landing catches (HLC) as the gold-standard. Field experiments were performed in Massavasse village, southern Mozambique. Simultaneous indoor and outdoor collections of nocturnal host-seeking mosquitoes were carried out using the SHK and HLC methods. The relative sampling efficiency of SHK was estimated as the ratio of the numbers of mosquitoes caught in SHK compared HLC. Proportionality and density-dependence between SHK and HLC catches were estimated by mean of Bayesian regression approaches. Results: A total of 69,758 and 27,359 host-seeking mosquitoes comprising nineteen species and four genera, were collected by HLC and SHK respectively. In general, SHK and HLC sampled similar numbers of mosquito species, with the exceptions of the least common species Aedes sudanensis, Ae. subargenteus, and Coquillettidia versicolor that were caught only by HLC. The relative sampling efficiency and proportionality between SHK and matched HLC catches varied greatly between species and collection site. However, all mosquitoes collected by SHK were unfed, confirming the Shockwè trap design's performance and reliability as a successful mosquito exposure free sampling approach. Conclusions: Results demonstrate that SHK is a safe and reliable human-exposure free device for monitoring the occurrence of a wide range of mosquito, including major malaria and arboviruses vector species. However, improvements are needed to increase its sampling efficiency for less abundant mosquito species.
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Affiliation(s)
- Ayubo Kampango
- Vectors Study Unit, Instituto Nacional de Saúde, Maputo Province, Vila de Marracuene, Mozambique
| | - Thomas A. Smith
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Ana Paula Abílio
- Vectors Study Unit, Instituto Nacional de Saúde, Maputo Province, Vila de Marracuene, Mozambique
| | - Elias Alberto Machoe
- Vectors Study Unit, Instituto Nacional de Saúde, Maputo Province, Vila de Marracuene, Mozambique
| | - Júlio Francisco Matusse
- Vectors Study Unit, Instituto Nacional de Saúde, Maputo Province, Vila de Marracuene, Mozambique
| | - João Pinto
- Global Health and Tropical Medicine, Institute of Hygiene and Tropical Medicine, Lisbon, Portugal
| | - Philip J. McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
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Gleave K, Guy A, Mechan F, Emery M, Murphy A, Voloshin V, Towers CE, Towers D, Ranson H, Foster GM, McCall PJ. Impacts of dual active-ingredient bed nets on the behavioural responses of pyrethroid resistant Anopheles gambiae determined by room-scale infrared video tracking. Malar J 2023; 22:132. [PMID: 37088828 PMCID: PMC10122874 DOI: 10.1186/s12936-023-04548-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 03/31/2023] [Indexed: 04/25/2023] Open
Abstract
BACKGROUND The success of insecticide treated bed nets (ITNs) for malaria vector control in Africa relies on the behaviour of various species of Anopheles. Previous research has described mosquito behavioural alterations resulting from widespread ITN coverage, which could result in a decrease in net efficacy. Here, behaviours were compared including timings of net contact, willingness to refeed and longevity post-exposure to two next-generation nets, PermaNet® 3.0 (P3 net) and Interceptor® G2 (IG2 net) in comparison with a standard pyrethroid-only net (Olyset Net™ (OL net)) and an untreated net. METHODS Susceptible and resistant Anopheles gambiae mosquitoes were exposed to the nets with a human volunteer host in a room-scale assay. Mosquito movements were tracked for 2 h using an infrared video system, collecting flight trajectory, spatial position and net contact data. Post-assay, mosquitoes were monitored for a range of sublethal insecticide effects. RESULTS Mosquito net contact was focused predominantly on the roof for all four bed nets. A steep decay in activity was observed for both susceptible strains when P3 net and OL net were present and with IG2 net for one of the two susceptible strains. Total mosquito activity was higher around untreated nets than ITNs. There was no difference in total activity, the number, or duration, of net contact, between any mosquito strain, with similar behaviours recorded in susceptible and resistant strains at all ITNs. OL net, P3 net and IG2 net all killed over 90% of susceptible mosquitoes 24 h after exposure, but this effect was not seen with resistant mosquitoes where mortality ranged from 16 to 72%. All treated nets reduced the willingness of resistant strains to re-feed when offered blood 1-h post-exposure, with a more pronounced effect seen with P3 net and OL net than IG2 net. CONCLUSION These are the first results to provide an in-depth description of the behaviour of susceptible and resistant Anopheles gambiae strains around next-generation bed nets using a room-scale tracking system to capture multiple behaviours. These results indicate that there is no major difference in behavioural responses between mosquito strains of differing pyrethroid susceptibility when exposed to these new ITNs under the experimental conditions used.
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Affiliation(s)
- Katherine Gleave
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Amy Guy
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Frank Mechan
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Mischa Emery
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Annabel Murphy
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | | | | | - David Towers
- School of Engineering, University of Warwick, Coventry, UK
| | - Hilary Ranson
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Geraldine M Foster
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Philip J McCall
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK.
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Carrasco-Tenezaca M, Jawara M, Lee DSH, Holmes MS, Ceesay S, McCall P, Pinder M, D'Alessandro U, Knudsen JB, Lindsay SW, Wilson AL. Effect of passive and active ventilation on malaria mosquito house entry and human comfort: an experimental study in rural Gambia. J R Soc Interface 2023; 20:20220794. [PMID: 37015266 PMCID: PMC10072938 DOI: 10.1098/rsif.2022.0794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023] Open
Abstract
Rural houses in sub-Saharan Africa are typically hot and allow malaria mosquitoes inside. We assessed whether passive or active ventilation can reduce house entry of malaria mosquitoes and cool a bedroom at night in rural Gambia. Two identical experimental houses were used: one ventilated and one unventilated (control). We evaluated the impact of (i) passive ventilation (solar chimney) and (ii) active ventilation (ceiling fan) on the number of mosquitoes collected indoors and environmental parameters (temperature, humidity, CO2, evaporation). Although the solar chimney did not reduce entry of Anopheles gambiae sensu lato, the ceiling fan reduced house entry by 91% compared with the control house. There were no differences in indoor nightly temperature, humidity or CO2 between intervention and control houses in either experiment. The solar chimney did not improve human comfort assessed using psychrometric analysis. While the ceiling fan improved human comfort pre-midnight, in the morning it was too cool compared with the control house, although this could be remedied through provision of blankets. Further improvements to the design of the solar chimney are needed. High air velocity in the ceiling fan house probably reduced mosquito house entry by preventing mosquito flight. Improved ventilation in houses may reduce malaria transmission.
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Affiliation(s)
| | - Musa Jawara
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Daniel Sang-Hoon Lee
- Architecture, Design and Conservation, The Royal Danish Academy, Philip De Langes Allé 10, Copenhagen 1435, Denmark
| | - Matthew S Holmes
- JDDK Architects, Millmount, Ponteland Rd, Cowgate, Newcastle upon Tyne NE5 3AL, England
| | - Sainey Ceesay
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Phillip McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Margaret Pinder
- Department of Biosciences, Durham University, Stockton Road, Durham, Durham DH1 3LE, UK
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Jakob B Knudsen
- Architecture, Design and Conservation, The Royal Danish Academy, Philip De Langes Allé 10, Copenhagen 1435, Denmark
| | - Steve W Lindsay
- Department of Biosciences, Durham University, Stockton Road, Durham, Durham DH1 3LE, UK
- London School of Hygiene & Tropical Medicine, Keppel St, Bloomsbury, London WC1E 7HT, UK
| | - Anne L Wilson
- Department of Biosciences, Durham University, Stockton Road, Durham, Durham DH1 3LE, UK
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
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Mbewe NJ, Rowland MW, Snetselaar J, Azizi S, Small G, Nimmo DD, Mosha FW. Efficacy of bednets with dual insecticide-treated netting (Interceptor® G2) on side and roof panels against Anopheles arabiensis in north-eastern Tanzania. Parasit Vectors 2022; 15:326. [PMID: 36109765 PMCID: PMC9479251 DOI: 10.1186/s13071-022-05454-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/29/2022] [Indexed: 11/25/2022] Open
Abstract
Background Optimising insecticide use and managing insecticide resistance are important to sustain gains against malaria using long-lasting insecticidal nets (LLINs). Restricting insecticides to where mosquitoes are most likely to make multiple contacts could reduce the quantity of insecticide needed to treat the nets. Previous studies have shown that nets partially treated with a pyrethroid insecticide had equivalent mortality compared to a fully treated net. This study compared the efficacy of: (i) whole Interceptor® G2 nets (IG2; a dual-active LLIN containing alpha-cypermethrin and chlorfenapyr), (ii) nets with roof panels made of IG2 netting, (iii) nets with side panels made of IG2 netting and (iv) whole untreated nets as test nets. Methods The study was conducted in cow-baited experimental huts, Moshi Tanzania, using a four-arm Latin square design. Test nets had 30 holes cut in panels to simulate a typical net after 2–3 year use. The trial data were analysed using generalized linear models with mortality, blood-feeding, exophily and deterrence against wild free-flying Anopheles arabiensis as outcomes and test nets as predictors. Results Mortality was significantly higher in the nets with roof IG2 [27%, P = 0.001, odds ratio (OR) = 51.0, 95% CI = 4.8–546.2), side IG2 (44%, P < 0.001, OR = 137.6, 95% CI = 12.2–1553.2] and whole IG2 (53%, P < 0.001, OR = 223.0, 95% CI = 19.07–2606.0) nettings than the untreated (1%) nets. Mortality was also significantly higher in the whole IG2 net compared to the net with roof IG2 netting (P = 0.009, OR = 4.4, 95% CI = 1.4–13.3). Blood feeding was 22% in untreated, 10% in roof IG2, 14% in side IG2 and 19% in whole IG2 nets. Exiting was 92% in untreated, 89% in roof IG2, 97% in side IG2 and 94% whole IG2 nets. Conclusion The results show that although the roof-treated IG2 net induced greater mortality compared to untreated nets, its efficacy was reduced compared to whole IG2 nets. Therefore, there was no benefit to be gained from restricting dual-active ingredient IG2 netting to the roof of nets. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-022-05454-w.
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12
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Hughes A, Matope A, Emery M, Steen K, Murray G, Ranson H, McCall PJ, Foster GM. A closer look at the WHO cone bioassay: video analysis of the hidden effects of a human host on mosquito behaviour and insecticide contact. Malar J 2022; 21:208. [PMID: 35778744 PMCID: PMC9248144 DOI: 10.1186/s12936-022-04232-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 06/20/2022] [Indexed: 12/04/2022] Open
Abstract
Background The WHO cone test is one of three tests currently used to evaluate the efficacy of insecticide-treated bed nets (ITNs). It generates two test outputs, knockdown and 24-h mortality, both indicative of immediate toxicity but that reveal little about the nature of mosquito and ITN interaction or how results translate to real-world settings. Methods A human arm held 5 mm behind the net surface acted as a host attractant during cone tests and a smartphone was used to capture mosquito behaviour in the cone. Post-exposure blood feeding and survival for nine days were recorded; ingested blood meal size was determined by measuring excreted haematin. Four strains of Anopheles gambiae (insecticide susceptible: Kisumu and N’gousso; insecticide resistant: Banfora and VK7) were tested with and without the host attractant using untreated, Permanet 2.0 and Olyset nets. Video recordings were scan sampled every five seconds to record mosquito positions on either the net, in flight or in contact with the cone. Generalized estimating equations were used to analyse all data except survival within nine days which was analysed using Weighted Cox Regression. Results Net contact was the most frequently recorded behaviour in all Anopheles spp. strains on all nets. Adding the human host as attractant triggered excitatory behaviours: in all strains, the magnitude of net contact was significantly decreased compared to tests without a host. ITN exposure altered the observed behaviour of the two susceptible strains, which exhibited a decreased response to the host during ITN tests. The resistant strains did not alter their behaviour during ITN tests. Significantly less net contact was observed during Olyset Net tests compared to Permanet 2.0. The host presence affected survival after exposure: Banfora and VK7 mosquitoes exposed to Permanet 2.0 with a host lived longer compared to tests performed without a host. However, mosquitoes that blood-fed and survived long enough to digest the blood meal did not exhibit significantly reduced longevity regardless of the presence of the host attractant. Conclusions Simple modifications to the WHO cone test and extension of post-test monitoring beyond the current 24 h enable detailed behavioural characterizations of individual ITNs to be compiled. The effects observed from testing with a host and including blood feeding suggest that more representative estimates of true of ITN efficacy are gained with these modifications than when using the current testing protocol. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04232-4.
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Affiliation(s)
- Angela Hughes
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Agnes Matope
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Mischa Emery
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Keith Steen
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Gregory Murray
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Philip J McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Geraldine M Foster
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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13
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Kamande DS, Odufuwa OG, Mbuba E, Hofer L, Moore SJ. Modified World Health Organization (WHO) Tunnel Test for Higher Throughput Evaluation of Insecticide-Treated Nets (ITNs) Considering the Effect of Alternative Hosts, Exposure Time, and Mosquito Density. INSECTS 2022; 13:562. [PMID: 35886738 PMCID: PMC9323354 DOI: 10.3390/insects13070562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 06/08/2022] [Accepted: 06/14/2022] [Indexed: 01/27/2023]
Abstract
The standard World Health Organization (WHO) tunnel test is a reliable laboratory bioassay used for "free-flying" testing of insecticide-treated nets (ITNs) bio-efficacy where mosquitoes pass through a ITN sample to reach a live animal bait. Multiple parameters (i.e., bait, exposure time, and mosquito density) may affect the outcomes measured in tunnel tests. Therefore, a comparison was conducted of alternative hosts, exposure time, and lower mosquito density against the current gold standard test (100 mosquitoes, animal bait, and 12-h exposure) as outlined in the WHO ITN evaluation guideline. This was done with the aim to make the tunnel test cheaper and with higher throughput to meet the large sample sizes needed for bio-efficacy durability monitoring of chlorfenapyr ITNs that must be evaluated in "free-flying" bioassays. Methods: A series of experiments were conducted in the WHO tunnel test to evaluate the impact of the following factors on bio-efficacy endpoints of mosquito mortality at 24-h (M24) and 72-h (M72) and blood-feeding success (BFS): (1) baits (rabbit, membrane, human arm); (2) exposure time in the tunnel (1 h vs. 12 h); and (3) mosquito density (50 vs. 100). Finally, an alternative bioassay using a membrane with 50 mosquitoes (membrane-50) was compared to the gold standard bioassay (rabbit with 100 mosquitoes, rabbit-100). Pyrethroid-resistant Anopheles arabiensis and pyrethroid susceptible Anopheles gambiae were used to evaluate Interceptor® and Interceptor® G2 ITNs. Results: Using a human arm as bait gave a very different BFS, which impacted measurements of M24 and M72. The same trends in M24, M72 and BFS were observed for both Interceptor® ITN and Interceptor® G2 unwashed and washed 20 times measured using the gold standard WHO tunnel test (rabbit-100) or rabbit with 50 mosquitoes (rabbit-50). M24, M72 and BFS were not statistically different when either 50 or 100 mosquitoes were used with rabbit bait in the tunnel bioassay for either the susceptible or resistant strains. No systematic difference was observed between rabbit-50 and rabbit-100 in the agreement by the Bland and Altman method (B&A). The mean difference was 4.54% (-22.54-31.62) in BFS and 1.71% (-28.71-32.12) in M72 for rabbit-50 versus rabbit-100. Similar M24, M72 and lower BFS was measured by membrane-50 compared to rabbit-100. No systematic difference was observed in the agreement between membrane-50 and rabbit-100, by B&A. The mean difference was 9.06% (-11.42-29.64) for BSF and -5.44% (-50.3-39.45) for M72. Both membrane-50, rabbit-50 and rabbit-100 predicted the superiority of Interceptor® G2 over Interceptor® ITN for the resistant strain on M72. Conclusion: These results demonstrate that WHO tunnel tests using rabbit bait may be run with 50 mosquitoes to increase sample sizes needed for bio-efficacy durability monitoring of ITNs in "free-flying" bioassays. Using a membrane feeder with 50 mosquitoes is a potential replacement for the WHO tunnel bioassay with animal bait if control blood feeding rates can be improved to 50% because blood feeding impacts mosquito survival after exposure to insecticides.
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Affiliation(s)
- Dismas S. Kamande
- The Nelson Mandela African Institution of Science and Technology (NM-AIST), Arusha P.O. Box 447, Tanzania;
- Vector Control Product Testing Unit (VCPTU), Ifakara Health Institute, Environmental Health, and Ecological Sciences, Bagamoyo P.O. Box 74, Tanzania; (O.G.O.); (E.M.)
| | - Olukayode G. Odufuwa
- Vector Control Product Testing Unit (VCPTU), Ifakara Health Institute, Environmental Health, and Ecological Sciences, Bagamoyo P.O. Box 74, Tanzania; (O.G.O.); (E.M.)
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical & Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland;
- Faculty of Science, University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Emmanuel Mbuba
- Vector Control Product Testing Unit (VCPTU), Ifakara Health Institute, Environmental Health, and Ecological Sciences, Bagamoyo P.O. Box 74, Tanzania; (O.G.O.); (E.M.)
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical & Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland;
- Faculty of Science, University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Lorenz Hofer
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical & Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland;
- Faculty of Science, University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Sarah J. Moore
- The Nelson Mandela African Institution of Science and Technology (NM-AIST), Arusha P.O. Box 447, Tanzania;
- Vector Control Product Testing Unit (VCPTU), Ifakara Health Institute, Environmental Health, and Ecological Sciences, Bagamoyo P.O. Box 74, Tanzania; (O.G.O.); (E.M.)
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical & Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland;
- Faculty of Science, University of Basel, Petersplatz 1, 4001 Basel, Switzerland
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14
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Ziegler R, Blanckenhorn WU, Mathis A, Verhulst NO. Video analysis of the locomotory behaviour of Aedes aegypti and Ae. japonicus mosquitoes under different temperature regimes in a laboratory setting. J Therm Biol 2022; 105:103205. [DOI: 10.1016/j.jtherbio.2022.103205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 01/11/2022] [Accepted: 02/02/2022] [Indexed: 10/19/2022]
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15
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Lissenden N, Armistead JS, Gleave K, Irish SR, Martin JL, Messenger LA, Moore SJ, Ngufor C, Protopopoff N, Oxborough R, Spiers A, Lees RS. Developing Consensus Standard Operating Procedures (SOPs) to Evaluate New Types of Insecticide-Treated Nets. INSECTS 2021; 13:7. [PMID: 35055850 PMCID: PMC8778287 DOI: 10.3390/insects13010007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 12/15/2021] [Accepted: 12/17/2021] [Indexed: 11/30/2022]
Abstract
In response to growing concerns over the sustained effectiveness of pyrethroid-only based control tools, new products are being developed and evaluated. Some examples of these are dual-active ingredient (AI) insecticide-treated nets (ITNs) which contain secondary insecticides, or synergist ITNs which contain insecticide synergist, both in combination with a pyrethroid. These net types are often termed 'next-generation' insecticide-treated nets. Several of these new types of ITNs are being evaluated in large-scale randomized control trials (RCTs) and pilot deployment schemes at a country level. However, no methods for measuring the biological durability of the AIs or synergists on these products are currently recommended. In this publication, we describe a pipeline used to collate and interrogate several different methods to produce a singular 'consensus standard operating procedure (SOP)', for monitoring the biological durability of three new types of ITNs: pyrethroid + piperonyl butoxide (PBO), pyrethroid + pyriproxyfen (PPF), and pyrethroid + chlorfenapyr (CFP). This process, convened under the auspices of the Innovation to Impact programme, sought to align methodologies used for conducting durability monitoring activities of next-generation ITNs.
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Affiliation(s)
- Natalie Lissenden
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (K.G.); (R.S.L.)
- Innovation to Impact, Pembroke Place, Liverpool L3 5QA, UK;
| | - Jennifer S. Armistead
- U.S. President’s Malaria Initiative, U.S. Agency for International Development, Washington, DC 20547, USA;
| | - Katherine Gleave
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (K.G.); (R.S.L.)
| | - Seth R. Irish
- U.S. President’s Malaria Initiative, Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA; (S.R.I.); (L.A.M.)
| | - Jackline L. Martin
- Kilimanjaro Christian Medical University College, National Institute for Medical Research, Moshi P.O. Box 2240, Tanzania;
| | - Louisa A. Messenger
- U.S. President’s Malaria Initiative, Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA; (S.R.I.); (L.A.M.)
| | - Sarah J. Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo P.O. Box 74, Tanzania;
- Nelson Mandela African Institution of Science and Technology, Arusha P.O. Box 477, Tanzania
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051 Basel, Switzerland
- Faculty of Science, University of Basel, St. Petersplatz 1, 4002 Basel, Switzerland
| | - Corine Ngufor
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK; (C.N.); (N.P.)
- Centre de Recherche Entomologique de Cotonou, Cotonou BP 2604, Benin
| | - Natacha Protopopoff
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK; (C.N.); (N.P.)
| | | | - Angus Spiers
- Innovation to Impact, Pembroke Place, Liverpool L3 5QA, UK;
| | - Rosemary S. Lees
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (K.G.); (R.S.L.)
- Innovation to Impact, Pembroke Place, Liverpool L3 5QA, UK;
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16
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Sutcliffe JF, Yin S. Effects of indoor air movement and ambient temperature on mosquito (Anopheles gambiae) behaviour around bed nets: implications for malaria prevention initiatives. Malar J 2021; 20:427. [PMID: 34717652 PMCID: PMC8557611 DOI: 10.1186/s12936-021-03957-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 10/18/2021] [Indexed: 11/10/2022] Open
Abstract
Background Until recently, relatively little research has been done on how mosquitoes behave around the occupied bed net in the indoor environment. This has been partly remedied in the last few years through laboratory and field studies, most of these using video methods and mosquito flight tracking. Despite these recent advances, understanding of the mosquito-bed net environment system, and the principles that underlie mosquito behaviour within it, is limited. This project aimed to further understand this system by studying the effects of gently moving air (such as might be introduced through room design to make the indoor environment more comfortable and conducive to ITN use) and warmer vs. cooler ambient conditions on mosquito activity around ITNs and other bed nets. Methods The activity of colonized female Anopheles gambiae around an occupied untreated bed net set up in a mosquito-proof tent in a large laboratory space was recorded under different ambient conditions using a laser detection-video recording system. Conditions tested were ‘cool’ (23–25 °C) and ‘warm’ (27–30 °C) air temperatures and the presence or absence of a cross-flow produced by a small central processing unit (CPU) fan pointed at the side of the net so that it produced a ‘low-’ or ‘high-’ speed cross-draught (approx. 0.1 and 0.4 m/s, respectively). Near-net activity in recordings was measured using video image analysis. Results In cool, still air conditions, more than 80% of near-net activity by An. gambiae occurred on the net roof. Introduction of the low-speed or high-speed cross-draught resulted in an almost total drop off in roof activity within 1 to 2 min and, in the case of the high-speed cross-draught, a complementary increase in activity on the net side. In warm, still conditions, near-net activity appeared to be lower overall than in cool, still air conditions and to be relatively less focussed on the roof. Introduction of the high-speed cross-draught in warm conditions resulted in a decrease in roof activity and increase in side activity though neither effect was statistically significant. Conclusions Results are interpreted in terms of the flow of the stimulatory odour plume produced by the net occupant which, consistent with established principles of fluid dynamics, appears to rise quickly and remain more intact above the net occupant in cool, still air than in warm, still air. Cross-draught effects are ascribed to the changes they cause in the flow of the host odour plume as opposed to mosquito flight directly. The implications of these results for house designs that promote indoor air movement, on bed net design, and on other vector control measures are discussed. How mosquitoes approach a net is influenced both by indoor temperature and ventilation and their interaction. This system is in need of further study. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03957-y.
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Affiliation(s)
- James F Sutcliffe
- Dept. Biology, Trent University, Peterborough, ON, Canada. .,Entomology Branch, US Centers for Disease Control and Prevention, Atlanta, GA, USA.
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17
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Hinze A, Lantz J, Hill SR, Ignell R. Mosquito Host Seeking in 3D Using a Versatile Climate-Controlled Wind Tunnel System. Front Behav Neurosci 2021; 15:643693. [PMID: 33776664 PMCID: PMC7991727 DOI: 10.3389/fnbeh.2021.643693] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/15/2021] [Indexed: 12/25/2022] Open
Abstract
Future anthropogenic climate change is predicted to impact sensory-driven behaviors. Building on recent improvements in computational power and tracking technology, we have developed a versatile climate-controlled wind tunnel system, in which to study the effect of climate parameters, including temperature, precipitation, and elevated greenhouse gas levels, on odor-mediated behaviors in insects. To establish a baseline for future studies, we here analyzed the host-seeking behavior of the major malaria vector mosquito, Anopheles gambiae sensu strico, to human odor and carbon dioxide (CO2), under tightly controlled climatic conditions, and isolated from potential background contamination by the presence of an experimenter. When presented with a combination of human foot odor and CO2 (case study I), mosquitoes engaged in faster crosswind flight, spent more time in the filamentous odor plume and targeted the odor source more successfully. In contrast, female An. gambiae s. s. presented with different concentrations of CO2 alone, did not display host-seeking behavior (case study II). These observations support previous findings on the role of human host-associated cues in host seeking and confirm the role of CO2 as a synergist, but not a host-seeking cue on its own. Future studies are aimed at investigating the effect of climate change on odor-mediated behavior in mosquitoes and other insects. Moreover, the system will be used to investigate detection and processing of olfactory information in various behavioral contexts, by providing a fine-scale analysis of flight behavior.
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Affiliation(s)
- Annika Hinze
- Disease Vector Group, Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Jörgen Lantz
- Jörgen Lantz Engineering Consulting Firm, Alnarp, Sweden
| | - Sharon R Hill
- Disease Vector Group, Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.,Max Planck Centre Next Generation Chemical Ecology, Uppsala, Sweden
| | - Rickard Ignell
- Disease Vector Group, Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.,Max Planck Centre Next Generation Chemical Ecology, Uppsala, Sweden
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18
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Jones J, Murray GPD, McCall PJ. A minimal 3D model of mosquito flight behaviour around the human baited bed net. Malar J 2021; 20:24. [PMID: 33413370 PMCID: PMC7792054 DOI: 10.1186/s12936-020-03546-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 12/12/2020] [Indexed: 02/08/2023] Open
Abstract
Background Advances in digitized video-tracking and behavioural analysis have enabled accurate recording and quantification of mosquito flight and host-seeking behaviours, facilitating development of individual (agent) based models at much finer spatial scales than previously possible. Methods Quantified behavioural parameters were used to create a novel virtual testing model, capable of accurately simulating indoor flight behaviour by a virtual population of host-seeking mosquitoes as they interact with and respond to simulated stimuli from a human-occupied bed net. The model is described, including base mosquito behaviour, state transitions, environmental representation and host stimulus representation. Results In the absence of a bed net and human host bait, flight distribution of the model population was relatively uniform throughout the arena. Introducing an unbaited untreated bed net induced a change in distribution with an increase in landing events on the net surface, predominantly on the sides of the net. Adding the presence of a simulated human bait dramatically impacted flight distribution patterns, exploratory foraging and, the number and distribution of landing positions on the net, which were determined largely by the orientation of the human within. The model replicates experimental results with free-flying living mosquitoes at human-occupied bed nets, where contact occurs predominantly on the top surface of the net. This accuracy is important as it quantifies exposure to the lethal insecticide residues that may be unique to the net roof (or theoretically any other surface). Number of net contacts and height of contacts decreased with increasing attractant dispersal noise. Conclusions Results generated by the model are an accurate representation of actual mosquito behaviour recorded at and around a human-occupied bed net in untreated and insecticide-treated nets. This fine-grained model is highly flexible and has significant potential for in silico screening of novel bed net designs, potentially reducing time and cost and accelerating the deployment of new and more effective tools for protecting against malaria in sub-Saharan Africa.
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Affiliation(s)
- Jeff Jones
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool, UK
| | - Gregory P D Murray
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool, UK
| | - Philip J McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool, UK.
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19
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Zhou G, Yu L, Wang X, Zhong D, Lee MC, Kibret S, Yan G. Behavioral response of insecticide-resistant mosquitoes against spatial repellent: A modified self-propelled particle model simulation. PLoS One 2020; 15:e0244447. [PMID: 33373422 PMCID: PMC7771694 DOI: 10.1371/journal.pone.0244447] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/09/2020] [Indexed: 11/19/2022] Open
Abstract
Rapidly increasing pyrethroid insecticide resistance and changes in vector biting and resting behavior pose serious challenges in malaria control. Mosquito repellents, especially spatial repellents, have received much attention from industry. We attempted to simulate interactions between mosquitoes and repellents using a machine learning method, the Self-Propelled Particle (SPP) model, which we modified to include attractiveness/repellency effects. We simulated a random walk scenario and scenarios with insecticide susceptible/resistant mosquitoes against repellent alone and against repellent plus attractant (to mimic a human host). Simulation results indicated that without attractant/repellent, mosquitoes would fly anywhere in the cage at random. With attractant, all mosquitoes were attracted to the source of the odor by the end. With repellent, all insecticide-susceptible mosquitoes eventually moved to the corner of the cage farthest from the repellent release point, whereas, a high proportion of highly resistant mosquitoes might reach the attractant release point (the human) earlier in the simulation. At fixed concentration, a high proportion of mosquitoes could be able to reach the host when the relative repellency efficacy (compare to attractant efficacy) was <1, whereas, no mosquitoes reached the host when the relative repellency efficacy was > 1. This result implies that repellent may not be sufficient against highly physiologically insecticide resistant mosquitoes, since very high concentrations of repellent are neither practically feasible nor cost-effective.
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Affiliation(s)
- Guofa Zhou
- Program in Public Health, University of California, Irvine, California, United States of America
| | - Leonard Yu
- Program in Public Health, University of California, Irvine, California, United States of America
| | - Xiaoming Wang
- Program in Public Health, University of California, Irvine, California, United States of America
| | - Daibin Zhong
- Program in Public Health, University of California, Irvine, California, United States of America
| | - Ming-chieh Lee
- Program in Public Health, University of California, Irvine, California, United States of America
| | - Solomon Kibret
- Program in Public Health, University of California, Irvine, California, United States of America
| | - Guiyun Yan
- Program in Public Health, University of California, Irvine, California, United States of America
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Voloshin V, Kröner C, Seniya C, Murray GPD, Guy A, Towers CE, McCall PJ, Towers DP. Diffuse retro-reflective imaging for improved video tracking of mosquitoes at human baited bednets. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191951. [PMID: 32537200 PMCID: PMC7277285 DOI: 10.1098/rsos.191951] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 04/06/2020] [Indexed: 05/09/2023]
Abstract
Robust imaging techniques for tracking insects have been essential tools in numerous laboratory and field studies on pests, beneficial insects and model systems. Recent innovations in optical imaging systems and associated signal processing have enabled detailed characterization of nocturnal mosquito behaviour around bednets and improvements in bednet design, a global essential for protecting populations against malaria. Nonetheless, there remain challenges around ease of use for large-scale in situ recordings and extracting data reliably in the critical areas of the bednet where the optical signal is attenuated. Here, we introduce a retro-reflective screen at the back of the measurement volume, which can simultaneously provide diffuse illumination, and remove optical alignment issues while requiring only one-sided access to the measurement space. The illumination becomes significantly more uniform, although noise removal algorithms are needed to reduce the effects of shot noise, particularly across low-intensity bednet regions. By systematically introducing mosquitoes in front of and behind the bednet in laboratory experiments, we are able to demonstrate robust tracking in these challenging areas. Overall, the retro-reflective imaging set-up delivers mosquito segmentation rates in excess of 90% compared to less than 70% with backlit systems.
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Affiliation(s)
- Vitaly Voloshin
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Christian Kröner
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | | | | | - Amy Guy
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | | | - Philip J. McCall
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - David P. Towers
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
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21
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Hughes A, Foster GM, Guy A, Matope A, Abe M, Towers D, McCall PJ. Quantifying late-stage host-seeking behaviour of Anopheles gambiae at the insecticidal net interface using a baited-box bioassay. Malar J 2020; 19:140. [PMID: 32264900 PMCID: PMC7140563 DOI: 10.1186/s12936-020-03213-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 03/28/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-treated nets (ITNs) are losing efficacy against pyrethroid-resistant malaria vector populations throughout Africa. Safeguarding bed net efficacy, vital for effective malaria control, requires greater knowledge of mosquito-ITN interactions and how this impacts on the mosquito. METHODS A purpose-built benchtop apparatus with a closed 10 cm cubic chamber (the 'Baited-box') was used to video record behaviour of individual free-flying female Anopheles gambiae during approach and blood-feeding on a human hand through untreated nets and ITNs at close range. Time and duration of defined behavioural events, and knockdown and mortality at 1- and 24-h post-exposure respectively, were recorded for pyrethroid susceptible and resistant mosquitoes. RESULTS Using three human volunteers differing in relative attractiveness to mosquitoes, 328 mosquitoes were individually tested. There were no significant differences between response rates to ITNs and untreated nets (P > 0.1) or between resistant (Tiassalé) and susceptible (Kisumu) mosquito strains, at untreated nets (P = 0.39) or PermaNet 2.0 (P = 1). The sequence of behavioural events from host-seeking to completion of blood-feeding was consistent in all tests but duration and start time of events involving net contact were reduced or delayed respectively with ITNs. Blood-feeding durations at untreated nets (means from 4.25 to 8.47 min (95% confidence interval (CI) = 3.39-9.89) at 3 human volunteers) were reduced by 37-50% at PermaNet 2.0, in susceptible (mean 2.59-4.72 min, 95% CI = 1.54-5.5, P = < 0.05) and resistant (mean 4.20 min, 95% CI = 3.42-4.97, P = 0.01) strains. Total accumulated net contact was approximately 50% lower at PermaNet and Olyset ITNs (P < 0.0001) in susceptible (two of the three volunteers) and resistant mosquitoes. Times prior to first net contact were similar at untreated nets and ITNs (P > 0.2), and neither ITN type showed detectable spatial repellency. After initial contact, blood-feeding commenced later at Olyset (mean 2.76 min, 95% CI = 1.74-3.76, P = 0.0009) and PermaNet (mean 2.4 min, 95% CI = 1.52-3.33, P = 0.0058) than untreated netting (mean 0.68 min, 95% CI = 0.42-0.94). CONCLUSIONS The baited box offers a simple method for detailed characterization of mosquito behavioural responses to insecticidal nets, for comparing entomological modes of action between nets and for defining the behavioural responses of particular mosquito strains or populations. The device has potential as a screening assay in the search for novel net treatments and for investigations into behavioural resistance mechanisms.
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Affiliation(s)
- Angela Hughes
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Geraldine M Foster
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Amy Guy
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Agnes Matope
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Mayumi Abe
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - David Towers
- Optical Engineering Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Philip J McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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22
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Barrier bednets target malaria vectors and expand the range of usable insecticides. Nat Microbiol 2019; 5:40-47. [PMID: 31792426 DOI: 10.1038/s41564-019-0607-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 10/11/2019] [Indexed: 11/08/2022]
Abstract
Transmission of Plasmodium falciparum malaria parasites occurs when nocturnal Anopheles mosquito vectors feed on human blood. In Africa, where malaria burden is highest, bednets treated with pyrethroid insecticide were highly effective in preventing mosquito bites and reducing transmission, and essential to achieving unprecedented reductions in malaria until 2015 (ref. 1). Since then, progress has stalled2, and with insecticidal bednets losing efficacy against pyrethroid-resistant Anopheles vectors3,4, methods that restore performance are urgently needed to eliminate any risk of malaria returning to the levels seen before their widespread use throughout sub-Saharan Africa5. Here, we show that the primary malaria vector Anopheles gambiae is targeted and killed by small insecticidal net barriers positioned above a standard bednet in a spatial region of high mosquito activity but zero contact with sleepers, opening the way for deploying many more insecticides on bednets than is currently possible. Tested against wild pyrethroid-resistant A. gambiae in Burkina Faso, pyrethroid bednets with organophosphate barriers achieved significantly higher killing rates than bednets alone. Treated barriers on untreated bednets were equally effective, without significant loss of personal protection. Mathematical modelling of transmission dynamics predicted reductions in clinical malaria incidence with barrier bednets that matched those of 'next-generation' nets recommended by the World Health Organization against resistant vectors. Mathematical models of mosquito-barrier interactions identified alternative barrier designs to increase performance. Barrier bednets that overcome insecticide resistance are feasible using existing insecticides and production technology, and early implementation of affordable vector control tools is a realistic prospect.
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23
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Massue DJ, Lorenz LM, Moore JD, Ntabaliba WS, Ackerman S, Mboma ZM, Kisinza WN, Mbuba E, Mmbaga S, Bradley J, Overgaard HJ, Moore SJ. Comparing the new Ifakara Ambient Chamber Test with WHO cone and tunnel tests for bioefficacy and non-inferiority testing of insecticide-treated nets. Malar J 2019; 18:153. [PMID: 31039788 PMCID: PMC6492396 DOI: 10.1186/s12936-019-2741-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/21/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-treated net (ITN) durability, measured through physical integrity and bioefficacy, must be accurately assessed in order to plan the timely replacement of worn out nets and guide procurement of longer-lasting, cost-effective nets. World Health Organization (WHO) guidance advises that new intervention class ITNs be assessed 3 years after distribution, in experimental huts. In order to obtain information on whole-net efficacy cost-effectively and with adequate replication, a new bioassay, the Ifakara Ambient Chamber Test (I-ACT), a semi-field whole net assay baited with human host, was compared to established WHO durability testing methods. METHODS Two experiments were conducted using pyrethroid-susceptible female adult Anopheles gambiae sensu stricto comparing bioefficacy of Olyset®, PermaNet® 2.0 and NetProtect® evaluated by I-ACT and WHO cone and tunnel tests. In total, 432 nets (144/brand) were evaluated using I-ACT and cone test. Olyset® nets (132/144) that did not meet the WHO cone test threshold criteria (≥ 80% mortality or ≥ 95% knockdown) were evaluated using tunnel tests with threshold criteria of ≥ 80% mortality or ≥ 90% feeding inhibition for WHO tunnel and I-ACT. Pass rate of nets tested by WHO combined standard WHO bioassays (cone/tunnel tests) was compared to pass in I-ACT only by net brand and time after distribution. RESULTS Overall, more nets passed WHO threshold criteria when tested with I-ACT than with standard WHO bioassays 92% vs 69%, (OR: 4.1, 95% CI 3.5-4.7, p < 0.0001). The proportion of Olyset® nets that passed differed if WHO 2005 or WHO 2013 LN testing guidelines were followed: 77% vs 71%, respectively. Based on I-ACT results, PermaNet® 2.0 and NetProtect® demonstrated superior mortality and non-inferior feeding inhibition to Olyset® over 3 years of field use in Tanzania. CONCLUSION Ifakara Ambient Chamber Test may have use for durability studies and non-inferiority testing of new ITN products. It measures composite bioefficacy and physical integrity with both mortality and feeding inhibition endpoints, using fewer mosquitoes than standard WHO bioassays (cone and tunnel tests). The I-ACT is a high-throughput assay to evaluate ITN products that work through either contact toxicity or feeding inhibition. I-ACT allows mosquitoes to interact with a host sleeping underneath a net as encountered in the field, without risk to human participants.
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Affiliation(s)
- Dennis J Massue
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland.
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland.
- National Institute for Medical Research, Amani Research Centre, P. O. Box 81, Muheza, Tanga, Tanzania.
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania.
| | - Lena M Lorenz
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Jason D Moore
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | | | - Samuel Ackerman
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | - Zawadi M Mboma
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - William N Kisinza
- National Institute for Medical Research, Amani Research Centre, P. O. Box 81, Muheza, Tanga, Tanzania
| | - Emmanuel Mbuba
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | - Selemani Mmbaga
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Hans J Overgaard
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway
| | - Sarah J Moore
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
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Spitzen J, Takken W. Keeping track of mosquitoes: a review of tools to track, record and analyse mosquito flight. Parasit Vectors 2018; 11:123. [PMID: 29499744 PMCID: PMC5834890 DOI: 10.1186/s13071-018-2735-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 02/21/2018] [Indexed: 12/13/2022] Open
Abstract
The health impact of mosquito-borne diseases causes a huge burden on human societies. Recent vector control campaigns have resulted in promising declines in incidence and prevalence of these diseases, notably malaria, but resistance to insecticides and drugs are on the rise, threatening to overturn these gains. Moreover, several vector-borne diseases have re-emerged, requiring prompt and effective response measures. To improve and properly implement vector control interventions, the behaviour of the vectors must be well understood with detailed examination of mosquito flight being an essential component. Current knowledge on mosquito behaviour across its life history is briefly presented, followed by an overview of recent developments in automated tracking techniques for detailed interpretation of mosquito behaviour. These techniques allow highly accurate recording and observation of mating, feeding and oviposition behaviour. Software programmes built with specific algorithms enable quantification of these behaviours. For example, the crucial role of heat on host landing and the multimodal integration of carbon dioxide (CO2) with other host cues, has been unravelled based on three-dimensional tracking of mosquito flight behaviour. Furthermore, the behavioural processes underlying house entry and subsequent host searching and finding can be better understood by analysis of detailed flight recordings. Further potential of these technologies to solve knowledge gaps is discussed. The use of tracking techniques can support or replace existing monitoring tools and provide insights on mosquito behaviour that can lead to innovative and more effective vector-control measures.
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Affiliation(s)
- Jeroen Spitzen
- Laboratory of Entomology, Wageningen University and Research, PO Box 16, 6700 AA Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research, PO Box 16, 6700 AA Wageningen, The Netherlands
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Cross-Study of Malaria Prevalence in History, Bed Net Utilization, and Knowledge about the Disease among Tanzanian College Students. Malar Res Treat 2018. [PMID: 29535856 PMCID: PMC5817302 DOI: 10.1155/2018/8137051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
University campuses are potential reservoirs of infectious diseases, but they are not in the research focus. It is obvious that the use of malaria preventive tools is extremely necessary in campus conditions in endemic countries. This study is the first malaria survey, conducted in a student campus in Tanzania. This cross-sectional study uncovered a surprisingly high prevalence of malaria history among students: 89,4% of 246 random respondents assume that they had malaria in history, among whom 145 (58,9%) suffered from the disease during the last year. And although students are relatively confident about the vector, parasite, and prevention measures of the disease, only 44,7% of the students use bed nets and 4,5% use a body spray or ointment daily. The others seldom use spray or ointment or do not care about the problem at all. This situation was found to be associated with two factors, financial and educational. Current results show that students are relatively educated on malaria, but they do not follow the malaria prevention guidance. It has become clear that at least proper informational propaganda of bed net use is required in Tanzanian university campuses.
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