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Lugenge AG, Odufuwa OG, Mseti JJ, Swai JK, Skovmand O, Moore SJ. Complete series method (CSM): a convenient method to reduce daily heterogeneity when evaluating the regeneration time (RT) of insecticide-treated nets (ITNs). Parasit Vectors 2024; 17:235. [PMID: 38778423 PMCID: PMC11110420 DOI: 10.1186/s13071-024-06323-4] [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: 03/18/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND "Regeneration time" (RT) denotes the time required to obtain a stable mortality rate for mosquitoes exposed to insecticide-treated nets (ITNs) after three consecutive washes of a net in a day. The RT informs the wash interval used to artificially age ITNs to simulate their lifetime performance under user conditions (20 washes). RT was estimated following World Health Organization (WHO) longitudinal method (LM) procedures. Longitudinal evaluation may introduce heterogeneity due to mosquito batch variability, complicating RT determination. To overcome this, nets at each stage of regeneration (i.e., 1, 2, 3, 5 and 7 days post wash) were prepared in advance and refrigerated; then, a complete regeneration series was tested with a single mosquito batch on 1 testing day, completing four series over 4 days. This study compared the complete series method (CSM) against the LM. METHODS The overall heterogeneity in the methods for estimating RT of one incorporated alpha-cypermethrin and piperonyl butoxide (PBO) and one incorporated permethrin with PBO ITNs was determined using laboratory-reared resistant Anopheles arabiensis under standard laboratory conditions. LM methods and CSM were compared in two experiments with refrigerated nets acclimated for (i) 2 h (test 1) and (ii) 3 h (test 2). Four regeneration replicates per day were tested per ITN product with 50 mosquitoes exposed per replicate (equivalent sample size to LM). The heterogeneity from these methods was compared descriptively. RESULTS The intra-method variability for unwashed pieces was minimal, with variance of 1.26 for CSM and 1.18 for LM. For unwashed nets, LM had substantially greater variance and ratio of LM:CSM was 2.66 in test 1 and 2.49 in test 2. The magnitude of mortality measured in bioassays depended on sample acclimation after refrigeration. CONCLUSIONS The CSM is a convenient method for determining the regeneration times. ITNs are prepared in advance, reducing pressure to prepare all samples to start on a single day. A complete regeneration series of samples is removed from the refrigerator, defrosted and evaluated on a single day with one mosquito batch reducing the influence of mosquito batch heterogeneity on results. Replicates can be conducted over several days but do not have to be conducted on consecutive days, allowing easy facility scheduling.
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Affiliation(s)
- Aidi Galus Lugenge
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania.
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania.
| | - Olukayode G Odufuwa
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Jilly Jackson Mseti
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania
| | - Johnson Kyeba Swai
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
| | | | - Sarah Jane Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
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Hancock PA, Ochomo E, Messenger LA. Genetic surveillance of insecticide resistance in African Anopheles populations to inform malaria vector control. Trends Parasitol 2024:S1471-4922(24)00115-6. [PMID: 38760258 DOI: 10.1016/j.pt.2024.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/24/2024] [Accepted: 04/26/2024] [Indexed: 05/19/2024]
Abstract
Insecticide resistance in malaria vector populations poses a major threat to malaria control, which relies largely on insecticidal interventions. Contemporary vector-control strategies focus on combatting resistance using multiple insecticides with differing modes of action within the mosquito. However, diverse genetic resistance mechanisms are present in vector populations, and continue to evolve. Knowledge of the spatial distribution of these genetic mechanisms, and how they impact the efficacy of different insecticidal products, is critical to inform intervention deployment decisions. We developed a catalogue of genetic-resistance mechanisms in African malaria vectors that could guide molecular surveillance. We highlight situations where intervention deployment has led to resistance evolution and spread, and identify challenges in understanding and mitigating the epidemiological impacts of resistance.
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Affiliation(s)
- Penelope A Hancock
- Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
| | - Eric Ochomo
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya; Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Louisa A Messenger
- Department of Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, USA; Parasitology and Vector Biology (PARAVEC) Laboratory, School of Public Health, University of Nevada, Las Vegas, USA
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Bonds J, Parsons G, Walker KJ, Murphy A, Lees RS, Nimmo D, Clayton J, Malone D. Comparative analysis of the Potter Tower and a new Track Sprayer for the application of residual sprays in the laboratory. Parasit Vectors 2024; 17:66. [PMID: 38365773 PMCID: PMC10870534 DOI: 10.1186/s13071-024-06168-x] [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: 08/08/2023] [Accepted: 01/27/2024] [Indexed: 02/18/2024] Open
Abstract
BACKGROUND Efforts to evaluate the residual efficacy of new indoor residual spraying (IRS) formulations have identified limitations with the industry standard laboratory sprayer, the Potter Spray Tower (PT). Calibrating the PT can be time-consuming, and the dosing of surfaces may not be as accurate or uniform as previously assumed. METHODS To address these limitations, the Micron Horizontal Track Sprayer with Spray Cabinet (TS) was developed to provide higher efficiency, ease of operation and deposition uniformity equal to or better than the PT. A series of studies were performed using a fluorescent tracer and three IRS formulations (Actellic® 300CS, K-Othrine WG250 and Suspend PolyZone) sprayed onto surfaces using either the PT or the TS. RESULTS Deposition volumes could be accurately calibrated for both spray systems. However, the uniformity of spray deposits was higher for the TS compared to the PT. Less than 12% of the volume sprayed using the PT reaches the target surface, with the remaining 88% unaccounted for, presumably vented out of the fume hood or coating the internal surfaces of the tower. In contrast, the TS deposits most of the spray on the floor of the spray chamber, with the rest contained therein. The total sprayed surface area in one run of the TS is 1.2 m2, and the operational zone for spray target placement is 0.7 m2, meaning that 58% of the applied volume deposits onto the targets. The TS can treat multiple surfaces (18 standard 15 × 15 cm tiles) in a single application, whereas the PT treats one surface at a time and a maximum area of around 0.0225 m2. An assessment of the time taken to perform spraying, including the setup, calibration and cleaning, showed that the cost of application using the TS was around 25-35 × less per tile sprayed. Standard operating procedures (SOPs) for calibration and use of both the Potter Tower and Track Sprayer have been developed. CONCLUSIONS Overall, the TS represents a significant improvement over the PT in terms of the efficiency and accuracy of IRS formulation applications onto test substrates and offers a useful additional tool for researchers and manufacturers wanting to screen new active ingredients or evaluate the efficacy of IRS or other sprayable formulations for insect control.
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Affiliation(s)
- Jane Bonds
- Bonds Consulting Group LLC, 3900 Wasp Street, Panama City Beach, FL, 32408, USA
| | - George Parsons
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Kyle J Walker
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Annabel Murphy
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Rosemary Susan Lees
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.
- Innovation to Impact, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Derric Nimmo
- Innovative Vector Control Consortium (IVCC), Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - John Clayton
- Micron Sprayers Ltd, Bromyard Industrial Estate, Bromyard, HR7 4HS, UK
| | - David Malone
- Bill & Melinda Gates Foundation, 500 5th Ave N, Seattle, WA, 98109, USA
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Agbevo A, Ahogni I, Menze B, Tungu P, Kemibala EE, Govoetchan R, Wondji C, Padonou GG, Ngufor C. Community evaluation of the physical and insecticidal durability of DuraNet® Plus, an alpha-cypermethrin and piperonyl butoxide incorporated mosquito net: protocol for a multi-country study in West, Central and East Africa. Arch Public Health 2023; 81:202. [PMID: 37986195 PMCID: PMC10662531 DOI: 10.1186/s13690-023-01217-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 11/09/2023] [Indexed: 11/22/2023] Open
Abstract
BACKGROUND Pyrethroid-PBO nets have demonstrated improved impact against clinical malaria transmitted by pyrethroid resistant mosquito vectors and are being scaled up across Africa. However very little is known about their physical and insecticidal durability under operational conditions. This study will investigate the attrition, fabric integrity, insecticide content and bioefficacy of DuraNet® Plus, a new WHO prequalified alphacypermethrin and PBO incorporated net developed by Shobikaa Impex Private Limited over 3 years of field use in communities in Benin, Cameroon and Tanzania. METHODS The study will be conducted in parallel in selected villages in Zakpota District in Benin, Mbalmayo, District in Cameroon and Muheza District in Tanzania. In each country, ~ 1800 households will be recruited and randomised to receive DuraNet® Plus or DuraNet® (a WHO prequalified alphacypermethrin-only ITN). Follow up surveys will be performed at 1 month post distribution to investigate adverse events and subsequently every 6-12 months to assess ITN attrition and fabric integrity following standard WHO procedures. A second cohort of nets will be withdrawn every 6-12 months and assessed for alpha-cypermethrin and PBO content and for entomological activity in laboratory bioassays (cone bioassays and tunnel tests). Alpha-cypermethrin bioefficacy will be monitored using the susceptible Anopheles gambiae Kisumu strain in cone bioassays while PBO bioefficacy will be monitored using pyrethroid resistant strains with overexpressed P450 enzymes in tunnel tests to determine the proportion of efficacious nets (≥ 95% knockdown, ≥ 80% mortality or ≥ 90% blood feeding inhibition in tunnels) at each time point. Nets withdrawn at 12, 24 and 36 months from each country will also be tested in experimental hut trials against wild free-flying pyrethroid resistant Anopheles gambiae sl in Côvè Benin to investigate the superiority of DuraNet® Plus over DuraNet® at each time point under semi field conditions. CONCLUSION This large-scale multi country trial will provide useful information on the durability of a pyrethroid-PBO net (DuraNet® Plus) in 3 different regions in sub-Saharan Africa. The methods proposed for bioefficacy testing could also contribute towards the development of new standardised guidelines for monitoring the insecticidal efficacy of pyrethroid-PBO nets under operational conditions.
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Affiliation(s)
- Abel Agbevo
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Panafrican Malaria Vector Research Consortium (PAMVERC-BENIN), Cotonou, Benin
- London School of Hygiene and Tropical Medicine (LSHTM), London, UK
| | - Idelphonse Ahogni
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Panafrican Malaria Vector Research Consortium (PAMVERC-BENIN), Cotonou, Benin
| | - Benjamin Menze
- Centre for Research in Infectious Diseases (CRID) ), Yaoundé, Cameroon
| | - Patrick Tungu
- Vector Control Training Centre (VCTC), Muheza, Tanzania
- National Institute for Medical Research (NIMR), Amani Research Centre, Tanga, Tanzania
| | | | - Renaud Govoetchan
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin
- Panafrican Malaria Vector Research Consortium (PAMVERC-BENIN), Cotonou, Benin
- London School of Hygiene and Tropical Medicine (LSHTM), London, UK
| | - Charles Wondji
- Centre for Research in Infectious Diseases (CRID) ), Yaoundé, Cameroon
- Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Corine Ngufor
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin.
- Panafrican Malaria Vector Research Consortium (PAMVERC-BENIN), Cotonou, Benin.
- London School of Hygiene and Tropical Medicine (LSHTM), London, UK.
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5
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Matope A, Lees RS, Spiers A, Foster GM. A bioassay method validation framework for laboratory and semi-field tests used to evaluate vector control tools. Malar J 2023; 22:289. [PMID: 37770855 PMCID: PMC10540336 DOI: 10.1186/s12936-023-04717-w] [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: 03/18/2023] [Accepted: 09/13/2023] [Indexed: 09/30/2023] Open
Abstract
Vector control interventions play a fundamental role in the control and elimination of vector-borne diseases. The evaluation of vector control products relies on bioassays, laboratory and semi-field tests using live insects to assess the product's effectiveness. Bioassay method development requires a rigorous validation process to ensure that relevant methods are used to capture appropriate entomological endpoints which accurately and precisely describe likely efficacy against disease vectors as well as product characteristics within the manufacturing tolerance ranges for insecticide content specified by the World Health Organization. Currently, there are no standardized guidelines for bioassay method validation in vector control. This report presents a framework for bioassay validation that draws on accepted validation processes from the chemical and healthcare fields and which can be applied for evaluating bioassays and semi-field tests in vector control. The validation process has been categorized into four stages: preliminary development; feasibility experiments; internal validation, and external validation. A properly validated method combined with an appropriate experimental design and data analyses that account for both the variability of the method and the product is needed to generate reliable estimates of product efficacy to ensure that at-risk communities have timely access to safe and reliable vector control products.
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Affiliation(s)
- Agnes Matope
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Rosemary S Lees
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
- Innovation to Impact (I2I), Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Angus Spiers
- Innovation to Impact (I2I), Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Geraldine M Foster
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, 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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Mbuba E, Odufuwa OG, Moore J, Mmbaga S, Tchicaya E, Edi C, Chalageri V, Uragayala S, Sharma A, Rahi M, Raghavendra K, Eapen A, Koenker H, Ross A, Moore SJ. Multi-country evaluation of the durability of pyrethroid plus piperonyl-butoxide insecticide-treated nets: study protocol. Malar J 2023; 22:30. [PMID: 36707886 PMCID: PMC9881340 DOI: 10.1186/s12936-023-04465-x] [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] [Received: 08/01/2022] [Accepted: 01/20/2023] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Mass distributions of long-lasting insecticidal nets (LLINs) have contributed to large reductions in the malaria burden. However, this success is in jeopardy due in part to the increasing pyrethroid-resistant mosquito population as well as low LLINs coverage in various areas because the lifespan of LLINs is often shorter than the interval between replenishment campaigns. New insecticide-treated nets (ITNs) containing pyrethroid and piperonyl-butoxide (PBO) have shown a greater reduction in the incidence of malaria than pyrethroid LLINs in areas with pyrethroid-resistant mosquitoes. However, the durability (attrition, bio-efficacy, physical integrity and chemical retainment) of pyrethroid-PBO ITNs under operational settings has not been fully characterized. This study will measure the durability of pyrethroid-PBO ITNs to assess whether they meet the World Health Organization (WHO) three years of operational performance criteria required to be categorized as "long-lasting". METHODS A prospective household randomized controlled trial will be conducted simultaneously in Tanzania, India and Côte d'Ivoire to estimate the field durability of three pyrethroid-PBO ITNs (Veeralin®, Tsara® Boost, and Olyset® Plus) compared to a pyrethroid LLIN: MAGNet®. Durability monitoring will be conducted up to 36 months post-distribution and median survival in months will be calculated. The proportion of ITNs: (1) lost (attrition), (2) physical integrity, (3) resistance to damage score, (4) meeting WHO bio-efficacy (≥ 95% knockdown after 1 h or ≥ 80% mortality after 24 h for WHO cone bioassay, or ≥ 90% blood-feeding inhibition or ≥ 80% mortality after 24 h for WHO Tunnel tests) criteria against laboratory-reared resistant and susceptible mosquitoes, and insecticidal persistence over time will be estimated. The non-inferiority of Veeralin® and Tsara® Boost to the first-in-class, Olyset® Plus will additionally be assessed for mortality, and the equivalence of 20 times washed ITNs compared to field aged ITNs will be assessed for mortality and blood-feeding inhibition endpoints in the Ifakara Ambient Chamber Test, Tanzania. CONCLUSION This will be the first large-scale prospective household randomized controlled trial of pyrethroid-PBO ITNs in three different countries in East Africa, West Africa and South Asia, simultaneously. The study will generate information on the replenishment intervals for PBO nets.
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Affiliation(s)
- Emmanuel Mbuba
- grid.414543.30000 0000 9144 642XVector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania ,grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, St. Petersplatz 1, 4002 Basel, Switzerland
| | - Olukayode G. Odufuwa
- grid.414543.30000 0000 9144 642XVector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania ,grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, St. Petersplatz 1, 4002 Basel, Switzerland ,grid.8991.90000 0004 0425 469XEpidemiology and Population Health Department, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT UK
| | - Jason Moore
- grid.414543.30000 0000 9144 642XVector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania ,grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland
| | - Selemani Mmbaga
- grid.414543.30000 0000 9144 642XVector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | - Emile Tchicaya
- grid.462846.a0000 0001 0697 1172Swiss Centre for Scientific Research in Côte d’Ivoire, 1303 Abidjan, Côte d’Ivoire ,Vegro Aps, Copenhagen, Denmark Refshalevej 213A,
| | - Constant Edi
- grid.462846.a0000 0001 0697 1172Swiss Centre for Scientific Research in Côte d’Ivoire, 1303 Abidjan, Côte d’Ivoire
| | - Vani Chalageri
- grid.419641.f0000 0000 9285 6594Field Unit, ICMR-National Institute of Malaria Research, Bangalore, Karnataka India
| | - Sreehari Uragayala
- grid.419641.f0000 0000 9285 6594Field Unit, ICMR-National Institute of Malaria Research, Bangalore, Karnataka India
| | - Amit Sharma
- grid.419641.f0000 0000 9285 6594ICMR-National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077 India
| | - Manju Rahi
- grid.19096.370000 0004 1767 225XICMR-Indian Council of Medical Research, Ansari Nagar, New Delhi, India
| | - Kamaraju Raghavendra
- grid.419641.f0000 0000 9285 6594ICMR-National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077 India
| | - Alex Eapen
- grid.19096.370000 0004 1767 225XField Unit, ICMR-Indian Council of Medical Research, Chennai, India
| | | | - Amanda Ross
- grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, St. Petersplatz 1, 4002 Basel, Switzerland
| | - Sarah J. Moore
- grid.414543.30000 0000 9144 642XVector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania ,grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, St. Petersplatz 1, 4002 Basel, Switzerland
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Lees RS, Fornadel C, Snetselaar J, Wagman J, Spiers A. Insecticides for Mosquito Control: Improving and Validating Methods to Strengthen the Evidence Base. INSECTS 2023; 14:116. [PMID: 36835685 PMCID: PMC9961412 DOI: 10.3390/insects14020116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 01/10/2023] [Indexed: 06/18/2023]
Abstract
Efforts to eliminate vector-borne diseases, for example malaria which caused an estimated 619,000 deaths in 2021 [...].
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Affiliation(s)
- Rosemary Susan Lees
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Innovation to Impact, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Christen Fornadel
- Innovative Vector Control Consortium (IVCC), Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Janneke Snetselaar
- Innovative Vector Control Consortium (IVCC), Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Joe Wagman
- PATH, 455 Massachusetts Ave NW, Washington, DC 20001, USA
| | - Angus Spiers
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Innovation to Impact, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
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Koinari M, Bubun N, Amos B, Kiari K, Lahu D, Karl S. WHO cone bioassay boards with or without holes: relevance for bioassay outcomes in long-lasting insecticidal net studies. Malar J 2022; 21:389. [PMID: 36536444 PMCID: PMC9762087 DOI: 10.1186/s12936-022-04412-2] [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] [Received: 05/13/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The World Health Organization (WHO) cone bioassay is a key method used to evaluate the bioefficacy of long-lasting insecticidal nets (LLINs) used for malaria control. These tests also play an important role in LLIN product prequalification and longitudinal monitoring. Standardization of these assays is therefore important. While many parameters for WHO cone bioassays are defined in the respective WHO guidelines, others are not. One of these undefined parameters is the exact configuration of the bioassay boards. In cone bioassays, LLIN samples are pinned onto a bioassay board for testing. Anecdotal evidence suggests that bioassay boards with holes behind the LLIN samples lead to greater exposure to insecticide, as the mosquitoes are 'forced to stand on the net material'. This may increase the key assay outcomes of 60 min knockdown (KD60) and 24 h mortality (M24). The present study tested this hypothesis in two facilities using two fully susceptible mosquito colonies. METHODS WHO cone bioassays were performed using bioassay boards with holes and boards without holes in parallel, following WHO guidelines. Five brands of LLINs with four new and unwashed whole net samples per brand were used (total of n = 20 whole nets). Five pieces per whole net sample were prepared in duplicate resulting in a total of n = 100 pairs. Knock-down (KD) was recorded in 10 min intervals within the first hour after exposure and mortality was recorded at 24 h. Assays with Anopheles farauti were done at the Papua New Guinea Institute of Medical Research (PNGIMR) and assays with Aedes aegypti were done at James Cook University, Australia. RESULTS Results varied not only with bioassay board configuration but also with mosquito colony. In particular, with An. farauti, a significantly higher M24 was observed when boards with holes were used, while this was not observed with Ae. aegypti. WHO cone bioassay results were systematically biased between the two facilities such that the use of An. farauti at PNGIMR predicted higher KD60 and M24. CONCLUSION The present study highlights the need for further harmonization of WHO cone bioassay methodology. Parameters such as bioassay board configuration and mosquito species systematically affect the observations, which impedes generalizability of WHO cone bioassay outcomes.
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Affiliation(s)
- Melanie Koinari
- grid.1011.10000 0004 0474 1797Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD Australia
| | - Nakei Bubun
- grid.417153.50000 0001 2288 2831Vector-Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Madang Province Papua New Guinea
| | - Brogan Amos
- grid.1011.10000 0004 0474 1797Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD Australia
| | - Kiari Kiari
- grid.417153.50000 0001 2288 2831Vector-Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Madang Province Papua New Guinea
| | - David Lahu
- grid.417153.50000 0001 2288 2831Vector-Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Madang Province Papua New Guinea
| | - Stephan Karl
- grid.1011.10000 0004 0474 1797Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD Australia ,grid.417153.50000 0001 2288 2831Vector-Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Madang Province Papua New Guinea
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