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Praulins G, Murphy-Fegan A, Gillespie J, Mechan F, Gleave K, Lees R. Unpacking WHO and CDC Bottle Bioassay Methods: A Comprehensive Literature Review and Protocol Analysis Revealing Key Outcome Predictors. Gates Open Res 2024; 8:56. [PMID: 39170853 PMCID: PMC11335745 DOI: 10.12688/gatesopenres.15433.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2024] [Indexed: 08/23/2024] Open
Abstract
Background Resistance monitoring is a key element in controlling vector-borne diseases. The World Health Organization (WHO) and Centres for Disease Control and Prevention (CDC) have each developed bottle bioassay methods for determining insecticide susceptibility in mosquito vectors which are used globally. Methods This study aimed to identify variations in bottle bioassay methodologies and assess the potential impact on the data that is generated. Our approach involved a systematic examination of existing literature and protocols from WHO and CDC, with a focus on the specifics of reported methodologies, variation between versions, and reported outcomes. Building on this, we experimentally evaluated the impact of several variables on bioassay results. Results Our literature review exposed a significant inconsistency in the how bioassay methods are reported, hindering reliable interpretation of data and the ability to compare results between studies. The experimental research provided further insight by specifically identifying two key factors that influence the outcomes of bioassays: mosquito dry weight and relative humidity (RH). This finding not only advances our comprehension of these assays but also underscores the importance of establishing precisely defined methodologies for resistance monitoring. The study also demonstrates the importance of controlling bioassay variables, noting the significant influence of wing length, as an indicator of mosquito size, on mortality rates in standardized bioassays. Conclusions Generating data with improved protocol consistency and precision will not only deepen our understanding of resistance patterns but also better inform vector control measures. We call for continued research and collaboration to refine and build consensus on bioassay techniques, to help bolster the global effort against vector-borne diseases like malaria.
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Affiliation(s)
- Giorgio Praulins
- Innovation to Impact (I2I), Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Annabel Murphy-Fegan
- Innovation to Impact (I2I), Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Jack Gillespie
- Innovation to Impact (I2I), Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Frank Mechan
- Innovation to Impact (I2I), Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Katherine Gleave
- Innovation to Impact (I2I), Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Rosemary Lees
- Innovation to Impact (I2I), Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
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Kweka EJ, Lyaruu LJ, Temba V, Msangi S, Ouma JO, Karanja W, Mahande AM, Himeidan YE. Impact of MiraNet® long-lasting insecticidal net against Anopheles arabiensis wild population of Northern Tanzania. Parasitol Res 2023; 122:1245-1253. [PMID: 36949289 DOI: 10.1007/s00436-023-07827-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 03/20/2023] [Indexed: 03/24/2023]
Abstract
Despite high levels of pyrethroid resistance reported in malaria vectors, long-lasting insecticidal nets (LNs) still play a key role in controlling malaria transmission. This study tested the efficacy of MiraNet®, a pyrethroid-based LN against a wild population of Anopheles arabiensis in northern Tanzania. DuraNet® was used as a positive control in this evaluation. Standard WHO laboratory bioefficacy evaluations of MiraNet and DuraNet that were unwashed or had been washed 20 times indicated optimal knockdown and mortality for both net types against a susceptible strain of Anopheles gambiae s.s. Standard experimental hut evaluations were conducted to evaluate the efficacy of both nets against a wild population of An. arabiensis. The killing effect of MiraNet was 54.5% for unwashed and 50% for 20 times washed while DuraNet achieved 44.4% mortality for unwashed and 47.4% for 20 times washed against wild An. arabiensis. Both DuraNet and MiraNet exhibited significantly higher killing effects (> 44.4%). There was no significant difference in deterrence or induced exophily detected between the treatment arms for either net. Additionally, there were no adverse effects reported among hut sleepers. The results of this study indicate that the pyrethroid net MiraNet can be used effectively against wild populations of An. gambiae s.l. of low to moderate resistant levels from Northern Tanzania.
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Affiliation(s)
- Eliningaya J Kweka
- Department of Medical Parasitology and Entomology, Catholic University of Health and Allied Sciences, P.O. Box 1464, Mwanza, Tanzania.
- Pesticides Bioefficacy Section, Tanzania Plant Health and Pesticides Authority, P.O. Box 3024, Arusha, Tanzania.
| | - Lucille J Lyaruu
- Pesticides Bioefficacy Section, Tanzania Plant Health and Pesticides Authority, P.O. Box 3024, Arusha, Tanzania
| | - Violet Temba
- Pesticides Bioefficacy Section, Tanzania Plant Health and Pesticides Authority, P.O. Box 3024, Arusha, Tanzania
| | - Shandala Msangi
- Pesticides Bioefficacy Section, Tanzania Plant Health and Pesticides Authority, P.O. Box 3024, Arusha, Tanzania
| | - Johnson O Ouma
- Africa Technical Research Centre, Vector Health International, P.O. Box 15500, Arusha, Tanzania
| | - Wycliffe Karanja
- Africa Technical Research Centre, Vector Health International, P.O. Box 15500, Arusha, Tanzania
| | - Aneth M Mahande
- Mabogini Field Station, Tanzania Plant Health and Pesticides Authority, Moshi, Tanzania
| | - Yousif E Himeidan
- Africa Technical Research Centre, Vector Health International, P.O. Box 15500, Arusha, Tanzania
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Das S, Máquina M, Phillips K, Cuamba N, Marrenjo D, Saúte F, Paaijmans KP, Huijben S. Fine-scale spatial distribution of deltamethrin resistance and population structure of Anopheles funestus and Anopheles arabiensis populations in Southern Mozambique. Malar J 2023; 22:94. [PMID: 36915131 PMCID: PMC10010967 DOI: 10.1186/s12936-023-04522-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 03/03/2023] [Indexed: 03/16/2023] Open
Abstract
BACKGROUND Insecticide resistance in malaria vectors can be spatially highly heterogeneous, yet population structure analyses frequently find relatively high levels of gene flow among mosquito populations. Few studies have contemporaneously assessed phenotypic, genotypic and population structure analysis on mosquito populations and none at fine geographical scales. In this study, genetic diversity, population structure, and insecticide resistance profiles of Anopheles funestus and Anopheles arabiensis were examined across mosquito populations from and within neighbouring villages. METHODS Mosquitoes were collected from 11 towns in southern Mozambique, as well as from different neighbourhoods within the town of Palmeira, during the peak malaria transmission season in 2016. CDC bottle bioassay and PCR assays were performed with Anopheles mosquitoes at each site to determine phenotypic and molecular insecticide resistance profiles, respectively. Microsatellite analysis was conducted on a subsample of mosquitoes to estimate genetic diversity and population structure. RESULTS Phenotypic insecticide resistance to deltamethrin was observed in An. funestus sensu stricto (s.s.) throughout the area, though a high level of mortality variation was seen. However, 98% of An. funestus s.s. were CYP6P9a homozygous resistant. An. arabiensis was phenotypically susceptible to deltamethrin and 99% were kdr homozygous susceptible. Both Anopheles species exhibited high allelic richness and heterozygosity. Significant deviations from Hardy-Weinberg equilibrium were observed, and high linkage disequilibrium was seen for An. funestus s.s., supporting population subdivision. However, the FST values were low for both anophelines (- 0.00457 to 0.04213), Nm values were high (9.4-71.8 migrants per generation), AMOVA results showed almost 100% genetic variation among and within individuals, and Structure analysis showed no clustering of An. funestus s.s. and An. arabiensis populations. These results suggest high gene flow among mosquito populations. CONCLUSION Despite a relatively high level of phenotypic variation in the An. funestus population, molecular analysis shows the population is admixed. These data indicate that CYP6P9a resistance markers do not capture all phenotypic variation in the area, but also that resistance genes of high impact are likely to easily spread in the area. Conversely, other strategies, such as transgenic mosquito release programmes will likely not face challenges in this locality.
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Affiliation(s)
- Smita Das
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA
- PATH, Seattle, WA, USA
| | - Mara Máquina
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique
| | - Keeley Phillips
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Nelson Cuamba
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
- PMI VectorLink Project, Abt Associates Inc., Maputo, Mozambique
| | - Dulcisaria Marrenjo
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
| | - Francisco Saúte
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique
| | - Krijn P Paaijmans
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, USA
- The Biodesign Center for Immunotherapy, Vaccines and Virotherapy, Arizona State University, Tempe, AZ, USA
- ISGlobal, Barcelona, Spain
| | - Silvie Huijben
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA.
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, USA.
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Kendie FA, Wale M, Nibret E, Ameha Z. Insecticide susceptibility status of Anopheles gambiae (s.l.) in and surrounding areas of Lake Tana, northwest Ethiopia. Trop Med Health 2023; 51:3. [PMID: 36639818 PMCID: PMC9838068 DOI: 10.1186/s41182-023-00497-w] [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: 08/29/2022] [Accepted: 01/04/2023] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Vector control is the most effective malaria control and prevention measure. Among these, IRS and LLINs are the most important chemical insecticide interventions used in malaria prevention and control strategies in Ethiopia. However, the long-term effectiveness of these strategies is under threat due to the emergency and spread of insecticide resistance in the principal malaria vector. Therefore, this study was carried out, under standardized laboratory conditions to assess the killing effect of some insecticides against An. gambiae s.l. METHODS Mosquitoes in late instar larvae and pupae stages were collected from different breeding habitats of the study sites using a soup ladle (350 ml capacity). The immature was reared to adults at optimum temperature and humidity in a field insectary using the WHO protocol. Four insecticides representing three chemical classes were used against adult mosquitoes. These were permethrin, deltamethrin, pirimiphos-methyl and bendiocarb. Susceptibility tests were carried out from September to December 2021 using the WHO standard procedures. Mortality rate, variation, interaction effect and knockdown times (KDT50 and KDT95%) were computed using descriptive statistics, multivariate analysis of variance and log-probit regression model using SPSS version 20 software. RESULTS Totally, 1300 Anopheles gambiae s.l. were tested to determine the susceptibility status to the four insecticides. Among these, 90.7% of them were susceptible to insecticides, whereas the remaining 9.3% of specimens were resistant to the insecticides. The results of the analysis of variance showed that mortality significantly varied between insecticides (F = 26.06, DF = 3, P < .0001), but not between study locations (F = 1.56, DF = 3, P = 0.212). On the other hand, the mean comparison of dead mosquitoes showed some signs of interaction between bendiocarb and locations, but not other insecticides and locations. CONCLUSIONS This study revealed that the knockdown times and effectiveness of different insecticides varied in different study sites. Therefore, insecticide resistance information is very essential for concerned bodies to make informed and evidence-based decisions on vector control.
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Affiliation(s)
- Fasil A. Kendie
- grid.442845.b0000 0004 0439 5951Department of Biology, Bahir Dar University, P.O. Box 79, Bahir Dar, Ethiopia
| | - Melaku Wale
- grid.442845.b0000 0004 0439 5951Department of Biology, Bahir Dar University, P.O. Box 79, Bahir Dar, Ethiopia
| | - Endalkachew Nibret
- grid.442845.b0000 0004 0439 5951Biotechnology Research Institute, Bahir Dar University, Bahir Dar, Ethiopia
| | - Zena Ameha
- grid.512241.1Amhara Public Health Institute, Bahir Dar, Ethiopia
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Al Nazawi AM, Weetman D. Age-dependence of susceptibility to single and repeated deltamethrin exposure in pyrethroid-resistant Aedes aegypti strains. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2023; 3:100121. [PMID: 37168454 PMCID: PMC10165399 DOI: 10.1016/j.crpvbd.2023.100121] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/04/2023] [Accepted: 04/05/2023] [Indexed: 05/13/2023]
Abstract
Monitoring insecticide resistance is crucial in disease-transmitting mosquitoes to allow assessment of viable candidate insecticides to use for control and to provide indication of changes in resistance. Insecticide resistance bioassays are typically performed on young female mosquitoes, yet disease is transmitted by older females, which may also have encountered insecticide multiple times during their adult life. If insecticide mortality rates increase with age directly, or indirectly via cumulative toxicity from repeated exposure, the strategy of testing young mosquitoes as the least susceptible cohort would be supported. We tested three hypotheses via examination of how age and cumulative exposure impact mortality rates to the pyrethroid deltamethrin in strains of Aedes aegypti from Jeddah, Saudi Arabia and the Cayman Islands, which show differences in resistance mechanisms. Females of different ages (5, 7, 10 and 14 days-old) were exposed using WHO tube assays to either a single dose of insecticide, or in a second experiment females (initially 5 days-old) were exposed daily over 10 days. Age only increased mortality in the Jeddah strain at 14 days-old and had no impact on the Cayman strain. This is consistent with greater impact linked to metabolic resistance in the Jeddah strain, though results from qPCR of four candidate genes, failed to provide evidence for a candidate underpinning an age-dependent change in resistance. With repeated exposure, mortality rates of surviving females decreased to very low levels, suggesting that surviving older cohorts of females may exhibit substantially lower susceptibility than young females in single exposure assays. Our results indicate that testing young females with a single insecticide exposure should capture minimum susceptibility for the majority of the population, but a small fraction of older females may prove particularly unresponsive to pyrethroid-based control measures.
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Affiliation(s)
- Ashwaq M. Al Nazawi
- Preventive Medicine Department, Public Health Directorate, Ministry of Health, Jeddah, 22246, Saudi Arabia
- Corresponding author.
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, United Kingdom
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Pinda PG, Msaky DS, Muyaga LL, Mshani IH, Njalambaha RM, Kihonda J, Bwanaly H, Ngowo HS, Kaindoa EW, Koekemoer LL, Okumu FO. Relationships between biological age, distance from aquatic habitats and pyrethroid resistance status of Anopheles funestus mosquitoes in south-eastern Tanzania. Malar J 2022; 21:365. [PMID: 36461058 PMCID: PMC9719249 DOI: 10.1186/s12936-022-04389-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 11/16/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Malaria transmission can be highly heterogeneous between and within localities, and is influenced by factors such as survival and biting frequencies of Anopheles mosquitoes. This study investigated the relationships between the biological age, distance from aquatic habitats and pyrethroid resistance status of Anopheles funestus mosquitoes, which currently dominate malaria transmission in south-east Tanzania. The study also examined how such relationships may influence malaria transmission and control. METHODS Female An. funestus were collected in houses located 50-100 m, 150-200 m or over 200 m from the nearest known aquatic habitats. The mosquitoes were exposed to 1×, 5× and 10× the diagnostic doses of deltamethrin or permethrin, or to the synergist, piperonyl butoxide (PBO) followed by the pyrethroids, then monitored for 24 h-mortality. Ovaries of exposed and non-exposed mosquitoes were dissected to assess parity as a proxy for biological age. Adults emerging from larval collections in the same villages were tested against the same insecticides at 3-5, 8-11 or 17-20 days old. FINDINGS Mosquitoes collected nearest to the aquatic habitats (50-100 m) had the lowest mortalities compared to other distances, with a maximum of 51% mortality at 10× permethrin. For the age-synchronized mosquitoes collected as larvae, the insecticide-induced mortality assessed at both the diagnostic and multiplicative doses (1×, 5× and 10×) increased with mosquito age. The highest mortalities at 1× doses were observed among the oldest mosquitoes (17-20 days). At 10× doses, mortalities were 99% (permethrin) and 76% (deltamethrin) among 8-11 day-olds compared to 80% (permethrin) and 58% (deltamethrin) among 3-5 day-olds. Pre-exposure to PBO increased the potency of both pyrethroids. The proportion of parous females was highest among mosquitoes collected farthest from the habitats. CONCLUSION In this specific setting, older An. funestus and those collected farthest from the aquatic habitats (near the centre of the village) were more susceptible to pyrethroids than the younger ones and those caught nearest to the habitats. These findings suggest that pyrethroid-based interventions may remain at least moderately effective despite widespread pyrethroid-resistance, by killing the older, less-resistant and potentially-infective mosquitoes. Further studies should investigate how and whether these observations could be exploited to optimize malaria control in different settings.
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Affiliation(s)
- Polius G Pinda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
| | - Dickson S Msaky
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Letus L Muyaga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Issa H Mshani
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Rukiyah M Njalambaha
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Japhet Kihonda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Hamis Bwanaly
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Emmanuel W Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- School of Life Sciences and Biotechnology, Nelson Mandela African Institution of Science and Technology, Arusha, United Republic of Tanzania
| | - Lizette L Koekemoer
- Wits Research Institute for Malaria, Faculty of Health Sciences, Centre for Emerging Zoonotic and Parasitic Diseases, University of the Witwatersrand, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.
- School of Life Sciences and Biotechnology, Nelson Mandela African Institution of Science and Technology, Arusha, United Republic of Tanzania.
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK.
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Yohana R, Chisulumi PS, Kidima W, Tahghighi A, Maleki-Ravasan N, Kweka EJ. Anti-mosquito properties of Pelargonium roseum (Geraniaceae) and Juniperus virginiana (Cupressaceae) essential oils against dominant malaria vectors in Africa. Malar J 2022; 21:219. [PMID: 35836226 PMCID: PMC9284854 DOI: 10.1186/s12936-022-04220-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 06/13/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND More than 90% of malaria cases occur in Africa where the disease is transmitted by Anopheles gambiae and Anopheles arabiensis. This study evaluated the anti-mosquito properties of Juniperus virginiana (JVO) and Pelargonium roseum (PRO) essential oils (EOs) against larvae and adults of An. gambiae sensu lato (s.l.) from East Africa in laboratory and semi-field conditions. METHODS EOs was extracted from the aerial green parts of Asian herbs by hydrodistillation. Their constituents were characterized by gas chromatography-mass spectrometry (GC-MS). Larvicidal activities of JVO, PRO, and PRO components [citronellol (CO), linalool (LO), and geraniol (GO)] were investigated against An. gambiae sensu stricto (s.s.). The percentage of knockdown effects and mortality rates of all oils were also evaluated in the adults of susceptible An. gambiae s.s. and permethrin-resistant An. arabiensis. RESULTS GC-MS analyses identified major constituents of JVO (sabinene, dl-limonene, β-myrcene, bornyl acetate, and terpinen-4-ol) and PRO (citronellol, citronellyl formate, L-menthone, linalool, and geraniol). Oils showed higher larvicidal activity in the laboratory than semi-field trials. The LC50 values for JVO/PRO were computed as 10.82-2.89/7.13-0.9 ppm and 10.75-9.06/13.63-8.98 ppm in laboratory and semi-field environments, respectively at exposure time of 24-72 h. The percentage of knockdown effects of the oils were also greater in An. gambiae s.s. than in An. arabiensis. Filter papers impregnated with JVO (100 ppm) and PRO (25 ppm) displayed 100% mortality rates for An. gambiae s.s. and 3.75% and 90% mortality rates, for An. arabiensis populations, respectively. Each component of CO, LO, and GO exhibited 98.13%, 97.81%, and 87.5%, respectively, and a mixture of the PRO components indicated 94.69% adult mortality to permethrin-resistant An. arabiensis. CONCLUSIONS The findings of this study show that PRO and its main constituents, compared to JVO, have higher anti-mosquito properties in terms of larvicidal, knockdown, and mortality when applied against susceptible laboratory and resistant wild populations of An. gambiae s.l. Consequently, these oils have the potential for the development of new, efficient, safe, and affordable agents for mosquito control.
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Affiliation(s)
- Revocatus Yohana
- Department of Zoology and Wildlife Conservation, College of Natural and Applied Sciences, University of Dar Es Salaam, Dar Es Salaam, Tanzania
| | - Paulo S Chisulumi
- Department of Zoology and Wildlife Conservation, College of Natural and Applied Sciences, University of Dar Es Salaam, Dar Es Salaam, Tanzania
| | - Winifrida Kidima
- Department of Zoology and Wildlife Conservation, College of Natural and Applied Sciences, University of Dar Es Salaam, Dar Es Salaam, Tanzania
| | - Azar Tahghighi
- Laboratory of Medicinal Chemistry, Department of Clinical Research, Pasteur Institute of Iran, Tehran, Iran.
| | | | - Eliningaya J Kweka
- Department of Medical Parasitology and Entomology, School of Medicine, Catholic University of Health Sciences, Mwanza, Tanzania.
- Tropical Pesticides Research Institute, Division of Livestock and Human Disease Vector Control Mosquito Section, Arusha, Tanzania.
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Lees RS, Armistead JS, Azizi S, Constant E, Fornadel C, Gimnig JE, Hemingway J, Impoinvil D, Irish SR, Kisinza W, Lissenden N, Mawejje HD, Messenger LA, Moore S, Ngufor C, Oxborough R, Protopopoff N, Ranson H, Small G, Wagman J, Weetman D, Zohdy S, Spiers A. Strain Characterisation for Measuring Bioefficacy of ITNs Treated with Two Active Ingredients (Dual-AI ITNs): Developing a Robust Protocol by Building Consensus. INSECTS 2022; 13:434. [PMID: 35621770 PMCID: PMC9144861 DOI: 10.3390/insects13050434] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/21/2022] [Accepted: 04/22/2022] [Indexed: 02/04/2023]
Abstract
Durability monitoring of insecticide-treated nets (ITNs) containing a pyrethroid in combination with a second active ingredient (AI) must be adapted so that the insecticidal bioefficacy of each AI can be monitored independently. An effective way to do this is to measure rapid knock down of a pyrethroid-susceptible strain of mosquitoes to assess the bioefficacy of the pyrethroid component and to use a pyrethroid-resistant strain to measure the bioefficacy of the second ingredient. To allow robust comparison of results across tests within and between test facilities, and over time, protocols for bioefficacy testing must include either characterisation of the resistant strain, standardisation of the mosquitoes used for bioassays, or a combination of the two. Through a series of virtual meetings, key stakeholders and practitioners explored different approaches to achieving these goals. Via an iterative process we decided on the preferred approach and produced a protocol consisting of characterising mosquitoes used for bioefficacy testing before and after a round of bioassays, for example at each time point in a durability monitoring study. We present the final protocol and justify our approach to establishing a standard methodology for durability monitoring of ITNs containing pyrethroid and a second AI.
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Affiliation(s)
- Rosemary S. Lees
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (J.H.); (N.L.); (H.R.); (D.W.)
- Innovation to Impact, Pembroke Place, Liverpool L3 5QA, UK;
| | - Jennifer S. Armistead
- U.S. President’s Malaria Initiative (PMI), U.S. Agency for International Development (USAID), Washington, DC 20547, USA;
| | - Salum Azizi
- KCMUCo-PAMVERC Test Facility, Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi P.O. Box 2240, Tanzania;
| | - Edi Constant
- Centre Suisse de Recherches Scientifiques (CSRS), Abidjan 1303, Côte d’Ivoire;
| | - Christen Fornadel
- Innovative Vector Control Consortium (IVCC), Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (C.F.); (G.S.)
| | - John E. Gimnig
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA; (J.E.G.); (D.I.); (S.Z.)
| | - Janet Hemingway
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (J.H.); (N.L.); (H.R.); (D.W.)
| | - Daniel Impoinvil
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA; (J.E.G.); (D.I.); (S.Z.)
- U.S. President’s Malaria Initiative (PMI), Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA;
| | - Seth R. Irish
- U.S. President’s Malaria Initiative (PMI), Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA;
| | - William Kisinza
- Amani Research Centre, National Institute for Medical Research, Muheza P.O. Box 81, Tanzania;
| | - Natalie Lissenden
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (J.H.); (N.L.); (H.R.); (D.W.)
- Innovation to Impact, Pembroke Place, Liverpool L3 5QA, UK;
| | - Henry D. Mawejje
- Infectious Diseases Research Collaboration (IDRC), Plot 2C Nakasero Hill Road, Kampala P.O. Box 7475, Uganda;
| | - Louisa A. Messenger
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK; (L.A.M.); (C.N.); (N.P.)
| | - Sarah Moore
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo P.O. Box 74, Tanzania;
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical & Public Health Institute, Kreuzstrasse 2, Allschwil, 4123 Basel, Switzerland
- Faculty of Science, University of Basel, Petersplatz 1, 4001 Basel, Switzerland
- Nelson Mandela African Institute of Science and Technology (NM-AIST), Tengeru P.O. Box 447, Tanzania
| | - Corine Ngufor
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK; (L.A.M.); (C.N.); (N.P.)
- Centre de Recherche Entomologique de Cotonou, Cotonou BP 2604, Benin
| | - Richard Oxborough
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd., Rockville, MD 20852, USA;
| | - Natacha Protopopoff
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK; (L.A.M.); (C.N.); (N.P.)
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (J.H.); (N.L.); (H.R.); (D.W.)
| | - Graham Small
- Innovative Vector Control Consortium (IVCC), Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (C.F.); (G.S.)
| | - Joseph Wagman
- Malaria and Neglected Tropical Diseases Program, PATH, Washington, DC 20001, USA;
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (J.H.); (N.L.); (H.R.); (D.W.)
| | - Sarah Zohdy
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA; (J.E.G.); (D.I.); (S.Z.)
- U.S. President’s Malaria Initiative (PMI), Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA;
| | - Angus Spiers
- Innovation to Impact, Pembroke Place, Liverpool L3 5QA, UK;
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9
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Wolie RZ, Koffi AA, Ahoua Alou LP, Sternberg ED, N'Nan-Alla O, Dahounto A, Yapo FHA, Kanh KMH, Camara S, Oumbouke WA, Tia IZ, Nguetta SPA, Thomas MB, NGuessan R. Evaluation of the interaction between insecticide resistance-associated genes and malaria transmission in Anopheles gambiae sensu lato in central Côte d'Ivoire. Parasit Vectors 2021; 14:581. [PMID: 34801086 PMCID: PMC8605510 DOI: 10.1186/s13071-021-05079-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 10/22/2021] [Indexed: 11/10/2022] Open
Abstract
Background There is evidence that the knockdown resistance gene (Kdr) L1014F and acetylcholinesterase-1 gene (Ace-1R) G119S mutations involved in pyrethroid and carbamate resistance in Anopheles gambiae influence malaria transmission in sub-Saharan Africa. This is likely due to changes in the behaviour, life history and vector competence and capacity of An. gambiae. In the present study, performed as part of a two-arm cluster randomized controlled trial evaluating the impact of household screening plus a novel insecticide delivery system (In2Care Eave Tubes), we investigated the distribution of insecticide target site mutations and their association with infection status in wild An. gambiae sensu lato (s.l.) populations. Methods Mosquitoes were captured in 40 villages around Bouaké by human landing catch from May 2017 to April 2019. Randomly selected samples of An. gambiae s.l. that were infected or not infected with Plasmodium sp. were identified to species and then genotyped for Kdr L1014F and Ace-1R G119S mutations using quantitative polymerase chain reaction assays. The frequencies of the two alleles were compared between Anopheles coluzzii and Anopheles gambiae and then between infected and uninfected groups for each species. Results The presence of An. gambiae (49%) and An. coluzzii (51%) was confirmed in Bouaké. Individuals of both species infected with Plasmodium parasites were found. Over the study period, the average frequency of the Kdr L1014F and Ace-1R G119S mutations did not vary significantly between study arms. However, the frequencies of the Kdr L1014F and Ace-1R G119S resistance alleles were significantly higher in An. gambiae than in An. coluzzii [odds ratio (95% confidence interval): 59.64 (30.81–131.63) for Kdr, and 2.79 (2.17–3.60) for Ace-1R]. For both species, there were no significant differences in Kdr L1014F or Ace-1R G119S genotypic and allelic frequency distributions between infected and uninfected specimens (P > 0.05). Conclusions Either alone or in combination, Kdr L1014F and Ace-1R G119S showed no significant association with Plasmodium infection in wild An. gambiae and An. coluzzii, demonstrating the similar competence of these species for Plasmodium transmission in Bouaké. Additional factors including behavioural and environmental ones that influence vector competence in natural populations, and those other than allele measurements (metabolic resistance factors) that contribute to resistance, should be considered when establishing the existence of a link between insecticide resistance and vector competence. Graphical Abstract ![]()
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Affiliation(s)
- Rosine Z Wolie
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire. .,Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire. .,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.
| | - Alphonsine A Koffi
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Ludovic P Ahoua Alou
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Eleanore D Sternberg
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Oulo N'Nan-Alla
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Amal Dahounto
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire
| | - Florent H A Yapo
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire
| | - Kpahe M H Kanh
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Soromane Camara
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Welbeck A Oumbouke
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Innovative Vector Control Consortium, IVCC, Liverpool, UK
| | - Innocent Z Tia
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.,Université Alassane Ouattara, Bouaké, Côte d'Ivoire
| | - Simon-Pierre A Nguetta
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Matthew B Thomas
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA
| | - Raphael NGuessan
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.,Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
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10
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Lissenden N, Kont MD, Essandoh J, Ismail HM, Churcher TS, Lambert B, Lenhart A, McCall PJ, Moyes CL, Paine MJI, Praulins G, Weetman D, Lees RS. Review and Meta-Analysis of the Evidence for Choosing between Specific Pyrethroids for Programmatic Purposes. INSECTS 2021; 12:insects12090826. [PMID: 34564266 PMCID: PMC8465213 DOI: 10.3390/insects12090826] [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: 08/05/2021] [Revised: 08/24/2021] [Accepted: 09/11/2021] [Indexed: 11/17/2022]
Abstract
Simple Summary A group of insecticides, called pyrethroids, are the main strategy for controlling the mosquito vectors of malaria. Pyrethroids are used in all insecticide-treated bednets, and many indoor residual spray programmes (in which insecticides are sprayed on the interior walls of houses). There are different types of pyrethroids within the class (e.g., deltamethrin and permethrin). Across the world, mosquitoes are showing signs of resistance to the pyrethroids, such as reduced mortality following contact. However, it is unclear if this resistance is uniform across the pyrethroid class (i.e., if a mosquito is resistant to deltamethrin, whether it is resistant to permethrin at the same level). In addition, it is not known if switching between different pyrethroids can be used to effectively maintain mosquito control when resistance to a single pyrethroid has been detected. This review examined the evidence from molecular studies, resistance testing from laboratory and field data, and mosquito behavioural assays to answer these questions. The evidence suggested that in areas where pyrethroid resistance exists, different mortality seen between the pyrethroids is not necessarily indicative of an operationally relevant difference in control performance, and there is no reason to rotate between common pyrethroids (i.e., deltamethrin, permethrin, and alpha-cypermethrin) as an insecticide resistance management strategy. Abstract Pyrethroid resistance is widespread in malaria vectors. However, differential mortality in discriminating dose assays to different pyrethroids is often observed in wild populations. When this occurs, it is unclear if this differential mortality should be interpreted as an indication of differential levels of susceptibility within the pyrethroid class, and if so, if countries should consider selecting one specific pyrethroid for programmatic use over another. A review of evidence from molecular studies, resistance testing with laboratory colonies and wild populations, and mosquito behavioural assays were conducted to answer these questions. Evidence suggested that in areas where pyrethroid resistance exists, different results in insecticide susceptibility assays with specific pyrethroids currently in common use (deltamethrin, permethrin, α-cypermethrin, and λ-cyhalothrin) are not necessarily indicative of an operationally relevant difference in potential performance. Consequently, it is not advisable to use rotation between these pyrethroids as an insecticide-resistance management strategy. Less commonly used pyrethroids (bifenthrin and etofenprox) may have sufficiently different modes of action, though further work is needed to examine how this may apply to insecticide resistance management.
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Affiliation(s)
- Natalie Lissenden
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Mara D. Kont
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London SW7 2BX, UK; (M.D.K.); (T.S.C.); (B.L.)
| | - John Essandoh
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Hanafy M. Ismail
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Thomas S. Churcher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London SW7 2BX, UK; (M.D.K.); (T.S.C.); (B.L.)
| | - Ben Lambert
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London SW7 2BX, UK; (M.D.K.); (T.S.C.); (B.L.)
| | - Audrey Lenhart
- U.S. Centers for Disease Control and Prevention, Entomology Branch, Division of Parasitic Diseases and Malaria, Atlanta, GA 30329, USA;
| | - Philip J. McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | | | - Mark J. I. Paine
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Giorgio Praulins
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Rosemary S. Lees
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
- Correspondence: ; Tel.: +44-(0)-151-705-3344
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11
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Marti-Soler H, Máquina M, Opiyo M, Alafo C, Sherrard-Smith E, Malheia A, Cuamba N, Sacoor C, Rabinovich R, Aide P, Saúte F, Paaijmans K. Effect of wall type, delayed mortality and mosquito age on the residual efficacy of a clothianidin-based indoor residual spray formulation (SumiShield™ 50WG) in southern Mozambique. PLoS One 2021; 16:e0248604. [PMID: 34351936 PMCID: PMC8341595 DOI: 10.1371/journal.pone.0248604] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 07/06/2021] [Indexed: 11/22/2022] Open
Abstract
Indoor residual spraying (IRS) is one of the main malaria vector control strategies in Mozambique alongside the distribution of insecticide treated nets. As part of the national insecticide resistance management strategy, Mozambique introduced SumiShield™ 50WG, a third generation IRS product, in 2018. Its residual efficacy was assessed in southern Mozambique during the 2018-2019 malaria season. Using a susceptible Anopheles arabiensis strain, residual efficacy was assessed on two different wall surfaces, cement and mud-plastered walls, using standard WHO (World Health Organization) cone bioassay tests at three different heights. Female mosquitoes of two age groups (2-5 and 13-26 day old) were exposed for 30 minutes, after which mortality was observed 24h, 48h, 72h, and 96h and 120h post-exposure to assess (delayed) mortality. Lethal times (LT) 90, LT50 and LT10 were estimated using Bayesian models. Mortality 24h post exposure was consistently below 80%, the current WHO threshold value for effective IRS, in both young and old mosquitoes, regardless of wall surface type. Considering delayed mortality, residual efficacies (mosquito mortality equal or greater than 80%) ranged from 1.5 to ≥12.5 months, with the duration depending on mortality time post exposure, wall type and mosquito age. Looking at mortality 72h after exposure, residual efficacy was between 6.5 and 9.5 months, depending on wall type and mosquito age. The LT50 and LT10 (i.e. 90% of the mosquitoes survive exposure to the insecticides) values were consistently higher for older mosquitoes (except for LT10 values for 48h and 72h post-exposure mortality) and ranged from 0.9 to 5.8 months and 0.2 to 7.8 months for LT50 and LT10, respectively. The present study highlights the need for assessing mosquito mortality beyond the currently recommended 24h post exposure. Failure to do so may lead to underestimation of the residual efficacy of IRS products, as delayed mortality will lead to a further reduction in mosquito vector populations and potentially negatively impact disease transmission. Monitoring residual efficacy on relevant wall surfaces, including old mosquitoes that are ultimately responsible for malaria transmission, and assessing delayed mortalities are critical to provide accurate and actionable data to guide vector control programmes.
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Affiliation(s)
| | - Mara Máquina
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Mercy Opiyo
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Celso Alafo
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- Goodbye Malaria, Tchau Tchau Malaria Foundation, Mozambique
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, United Kingdom
| | - Arlindo Malheia
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Nelson Cuamba
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
- PMI VectorLink Project, Abt Associates Inc., Maputo, Mozambique
| | - Charfudin Sacoor
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Regina Rabinovich
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Pedro Aide
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- Instituto Nacional da Saúde, Ministério da Saúde, Maputo, Mozambique
| | - Francisco Saúte
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Krijn Paaijmans
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- The Biodesign Center for Immunotherapy, Vaccines, and Virotherapy, Arizona State University, Tempe, Arizona, United States of America
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12
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The Impact of Insecticide Pre-Exposure on Longevity, Feeding Succession, and Egg Batch Size of Wild Anopheles gambiae s.l. J Trop Med 2020; 2020:8017187. [PMID: 33061994 PMCID: PMC7539113 DOI: 10.1155/2020/8017187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 09/11/2020] [Accepted: 09/19/2020] [Indexed: 11/18/2022] Open
Abstract
Background Insecticide resistance among the vector population is the main threat to existing control tools available. The current vector control management options rely on applications of recommended public health insecticides, mainly pyrethroids through long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). Regular monitoring of insecticide resistance does not provide information on important factors that affect parasite transmission. Such factors include vector longevity, vector competence, feeding success, and fecundity. This study investigated the impacts of insecticide resistance on longevity, feeding behaviour, and egg batch size of Anopheles gambiae s.l. Method The larval sampling was conducted in rice fields using a standard dipper (350 ml) and reared to adults in field insectary. A WHO susceptibility test was conducted using standard treated permethrin (0.75%) and deltamethrin (0.05%) papers. The susceptible Kisumu strain was used for reference. Feeding succession and egg batch size were monitored for all survivors and control. Results The results revealed that mortality rates declined by 52.5 and 59.5% for permethrin and deltamethrin, respectively. The mortality rate for the Kisumu susceptible strain was 100%. The survival rates of wild An. gambiae s.l. was between 24 and 27 days. However, the Kisumu susceptible strain blood meal feeding was significantly higher than resistant colony (t = 2.789, df = 21, P=0.011). Additionally, the susceptible An. gambiae s.s. laid more eggs than the resistant An.gambiae s.l. colony (Χ2 = 1366, df = 1, P ≤ 0.05). Conclusion It can, therefore, be concluded that the wild An. gambiae s.l. had increased longevity, blood feeding, and small egg batch size compared to Kisumu susceptible colonies.
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13
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Kweka EJ, Mazigo HD, Lyaruu LJ, Mausa EA, Venter N, Mahande AM, Coetzee M. Anopheline Mosquito Species Composition, Kdr Mutation Frequency, and Parasite Infectivity Status in Northern Tanzania. JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:933-938. [PMID: 31923308 DOI: 10.1093/jme/tjz245] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Indexed: 06/10/2023]
Abstract
The scaling-up of malaria control interventions in northern Tanzania has resulted in a decline in malaria prevalence and vector species composition. Despite this achievement, residual malaria transmission remains a concern in the area. The main aim of this study was to investigate malaria vector species composition, parasite infectivity rates, and the presence of insecticide knockdown resistance (kdr) mutations in three sites that have experienced a significant decline in malaria in northern Tanzania. Adult mosquitoes were sampled using light traps in houses and hand-aspirators in cowsheds, whereas the standard dipping method was used for sampling mosquito larvae. Adult mosquitoes identified as Anopheles gambiae s.l. and An. funestus s.l. and larval stages III and IV of An. gambiae s.l. were stored in absolute ethanol for further laboratory molecular identification. The identified species in the An. gambiae complex were An. gambiae s.s., An. merus, An. quadriannulatus, and An. arabiensis, whereas the An. funestus group comprised An. funestus s.s., An. rivulorum, and An. leesoni. For An. gambiae s.s. analyzed from Zeneth, 47.6% were kdr-East homozygous susceptible, 35.7% kdr-East heterozygous resistant, 9.6% kdr-East homozygous resistant, and 7.1% undefined, whereas specimens from Kwakibuyu were 45.5% kdr-East homozygous susceptible, 32.7% kdr-East heterozygous resistant, 16.3% kdr-East homozygous resistant, and 5.5% undefined. There were no kdr-West alleles identified from any specimen. The overall malaria parasite infectivity rate was 0.75%. No infections were found in Moshi. The findings indicate that populations of the major malaria vector mosquitoes are still present in the study area, with An. funestus taking a lead in malaria transmission.
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Affiliation(s)
- Eliningaya J Kweka
- Division of Livestock and Human Diseases Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania
- Department of Medical Parasitology and Entomology, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Humphrey D Mazigo
- Department of Medical Parasitology and Entomology, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Lucile J Lyaruu
- Division of Livestock and Human Diseases Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania
| | - Emmanuel A Mausa
- National Plant Genetic Resource Centre, Tropical Pesticides Research Institute, Arusha, Tanzania
| | - Nelius Venter
- Wits Research Institute for Malaria and Wits/MRC Collaborating Centre for Multi-disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging, Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Aneth M Mahande
- Mabogini Field Station, Tropical Pesticides Research Institute, Moshi, Tanzania
| | - Maureen Coetzee
- Wits Research Institute for Malaria and Wits/MRC Collaborating Centre for Multi-disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging, Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
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14
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Holmes CJ, Benoit JB. Biological Adaptations Associated with Dehydration in Mosquitoes. INSECTS 2019; 10:insects10110375. [PMID: 31661928 PMCID: PMC6920799 DOI: 10.3390/insects10110375] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 12/05/2022]
Abstract
Diseases that are transmitted by mosquitoes are a tremendous health and socioeconomic burden with hundreds of millions of people being impacted by mosquito-borne illnesses annually. Many factors have been implicated and extensively studied in disease transmission dynamics, but knowledge regarding how dehydration impacts mosquito physiology, behavior, and resulting mosquito-borne disease transmission remain underdeveloped. The lapse in understanding on how mosquitoes respond to dehydration stress likely obscures our ability to effectively study mosquito physiology, behavior, and vectorial capabilities. The goal of this review is to develop a profile of factors underlying mosquito biology that are altered by dehydration and the implications that are related to disease transmission.
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Affiliation(s)
- Christopher J Holmes
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
| | - Joshua B Benoit
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
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15
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Kweka EJ, Tungu PK, Mahande AM, Mazigo HD, Sayumwe S, Msangi S, Lyaruu L, Waweru J, Kisinza W, Wangai J. Bio-efficacy and wash resistance of MAGNet long-lasting insecticidal net against wild populations of Anopheles funestus in experimental huts in Muheza, Tanzania. Malar J 2019; 18:335. [PMID: 31570107 PMCID: PMC6771101 DOI: 10.1186/s12936-019-2973-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 09/24/2019] [Indexed: 11/30/2022] Open
Abstract
Background The decline in malaria cases and vectors is major milestone in fighting against malaria. The efficacy of MAGNet long-lasting insecticidal nets (MAGNet LLIN), an alpha-cypermethrin incorporated long-lasting net, with the target dose ± 25% of 5.8 g active ingredient (AI)/kg (4.35–7.25 g AI/kg) was evaluated in six veranda-trap experimental huts in Muheza, Tanzania against freely flying wild population of Anopheles funestus. Methods MAGNet LLINs were tested against wild, free-flying, host-seeking An. funestus mosquitoes over a period of 6 weeks (total of 36 nights in the huts). MAGNet LLIN efficacy was determined in terms of mosquito mortality, blood-feeding inhibition, deterrence, induced exiting, personal protection, and insecticidal killing over 20 washes according to WHO standardized procedures. Efficacy was compared with reference to a WHOPES recommended approved LLINs (DuraNet) and to a net conventionally treated (CTN) treated with alpha-cypermethrin at WHO-recommended dose and washed to just before cut-off point. The efficacy of MAGNet was evaluated in experimental huts against wild, free-flying, pyrethroid-resistant An. funestus. The WHO-susceptibility method was used to detect resistance in wild Anopheles exposed to 0.75% permethrin. Mosquito mortality, blood-feeding inhibition and personal protection were compared between untreated nets and standard LLINs. Blood-feeding rates were recorded and compared between the 20 times washed; blood-feeding rates between 20 times washed MAGNet LLIN and 20 times washed WHOPES-approved piperonyl butoxide (PBO)/pyrethroid were not statistically different (p > 0.05). Results The results have evidently shown that MAGNet LLIN provides similar blood-feeding inhibition, exophily, mortality, and deterrence to the standard approved LLIN, thus meeting the WHOPES criteria for blood feeding. The significantly high feeding inhibition and personal protection over pyrethroid-resistant An. funestus recorded by both unwashed and 20 times washed MAGNet compared to the unwashed DuraNet, the WHOPES-approved standard pyrethroid-only LLIN provides proof of MAGNet meeting Phase II WHOPES criteria for a LLIN. Conclusion Based on this study, MAGNet has been shown to have a promising impact on protection when 20 times washed against a highly resistant population of An. funestus.
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Affiliation(s)
- Eliningaya J Kweka
- Department of Medical Parasitology and Entomology, School of Medicine, Catholic University of Health and Allied Sciences, P.O. Box 1464, Mwanza, Tanzania. .,Mosquito Section, Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, Tanzania.
| | - Patrick K Tungu
- Amani Medical Research Centre, National Institute for Medical Research, P.O.Box 81, Muheza, Tanga, Tanzania
| | - Aneth M Mahande
- Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, Mabogini Field Station, Moshi, Tanzania
| | - Humphrey D Mazigo
- Mosquito Section, Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, Tanzania
| | - Subira Sayumwe
- Mosquito Section, Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, Tanzania
| | - Shandala Msangi
- Department of Medical Parasitology and Entomology, School of Medicine, Catholic University of Health and Allied Sciences, P.O. Box 1464, Mwanza, Tanzania
| | - Lucile Lyaruu
- Mosquito Section, Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, Tanzania
| | - John Waweru
- PestNet Kenya Ltd, P.O. BOX 51533-00200, Nairobi, Kenya
| | - William Kisinza
- Amani Medical Research Centre, National Institute for Medical Research, P.O.Box 81, Muheza, Tanga, Tanzania
| | - James Wangai
- PestNet Kenya Ltd, P.O. BOX 51533-00200, Nairobi, Kenya
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Chen S, Qin Q, Zhong D, Fang X, He H, Wang L, Dong L, Lin H, Zhang M, Cui L, Yan G. Insecticide Resistance Status and Mechanisms of Anopheles sinensis (Diptera: Culicidae) in Wenzhou, an Important Coastal Port City in China. JOURNAL OF MEDICAL ENTOMOLOGY 2019; 56:803-810. [PMID: 30715428 PMCID: PMC6467641 DOI: 10.1093/jme/tjz001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Indexed: 06/04/2023]
Abstract
Although scaled-up interventions and effective control efforts have drastically reduced malaria morbidity and mortality, malaria remains a serious threat to public health worldwide. Anopheles sinensis Wiedemann 1828 is a historically important vector of Plasmodium vivax (Haemosporida: Plasmodiidae) malaria in China. Insecticide resistance has become a major obstacle to vector-borne disease control. However, little is known about the insecticide resistance of An. sinensis in Wenzhou, an important coastal port city in Zhejiang province, China. The aim of this study was to examine insecticide resistance and mechanisms in An. sinensis field mosquito populations. Evidence of multiple insecticide resistance was found in An. sinensis adult female populations. Medium to high frequencies of target site kdr together with fixed ace-1 mutations was detected in both the Ruian and Yongjia populations. Both populations showed an association between kdr L1014 mutation and resistance phenotype when tested against deltamethrin and DDT. Significantly different metabolic enzyme activities were found between the susceptible laboratory strain and field-collected mosquitoes from both Ruian and Yongjia. Both field collected An. sinensis populations exhibited significantly higher P450 enzyme activity compared with the laboratory strain, while the field-collected resistant mosquitoes exhibited various GST and COE enzyme activities. These results indicate multiple resistance mechanisms in An. sinensis field populations. Effective implementation of insecticide resistance management strategies is urgently needed. The data collected in this study will be valuable for modeling insecticide resistance spread and vector-control interventions.
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Affiliation(s)
- Shixin Chen
- College of Medical and Health, Lishui University, Lishui, China
| | - Qian Qin
- College of Medical and Health, Lishui University, Lishui, China
- Department of Parasitology, Wenzhou Medical University, Wenzhou, China
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA
| | - Xia Fang
- Department of Parasitology, Wenzhou Medical University, Wenzhou, China
| | - Hanjiang He
- College of Medical and Health, Lishui University, Lishui, China
| | - Linlin Wang
- Department of Parasitology, Wenzhou Medical University, Wenzhou, China
| | - Lingjun Dong
- Department of Parasitology, Wenzhou Medical University, Wenzhou, China
| | - Haiping Lin
- Department of Parasitology, Wenzhou Medical University, Wenzhou, China
| | - Mengqi Zhang
- Department of Parasitology, Wenzhou Medical University, Wenzhou, China
| | - Liwang Cui
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA
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Machani MG, Ochomo E, Sang D, Bonizzoni M, Zhou G, Githeko AK, Yan G, Afrane YA. Influence of blood meal and age of mosquitoes on susceptibility to pyrethroids in Anopheles gambiae from Western Kenya. Malar J 2019; 18:112. [PMID: 30940139 PMCID: PMC6444593 DOI: 10.1186/s12936-019-2746-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 03/25/2019] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Physiological characteristics (age and blood feeding status) of malaria vectors can influence their susceptibility to the current vector control tools that target their feeding and resting behaviour. To ensure the sustainability of the current and future vector control tools an understanding of how physiological characteristics may contribute to insecticide tolerance in the field is fundamental for shaping resistance management strategies and vector control tools. The aim of this study was to determine whether blood meal and mosquito age affect pyrethroid tolerance in field-collected Anopheles gambiae from western Kenya. METHODS Wild mosquito larvae were reared to adulthood alongside the pyrethroid-susceptible Kisumu strain. Adult females from the two populations were monitored for deltamethrin resistance when they were young at 2-5 days old and older 14-16 days old and whether fed or unfed for each age group. Metabolic assays were also performed to determine the level of detoxification enzymes. Mosquito specimens were further identified to species level using the polymerase chain reaction (PCR) method. RESULTS Anopheles gambiae sensu stricto was the predominant species comprising 96% of specimens and 2.75% Anopheles arabiensis. Bioassay results showed reduced pyrethroid induced mortality with younger mosquitoes compared to older ones (mortality rates 83% vs. 98%), independently of their feeding status. Reduced mortality was recorded with younger females of which were fed compared to their unfed counterparts of the same age with a mortality rate of 35.5% vs. 83%. Older blood-fed females showed reduced susceptibility after exposure when compared to unfed females of the same age (mortality rates 86% vs. 98%). For the Kisumu susceptible population, mortality was straight 100% regardless of age and blood feeding status. Blood feeding status and mosquito age had an effect on enzyme levels in both populations, with blood fed individuals showing higher enzyme elevations compared to their unfed counterparts (P < 0.0001). The interaction between mosquito age and blood fed status had significant effect on mosquito mortality. CONCLUSION The results showed that mosquito age and blood feeding status confers increased tolerance to insecticides as blood feeding may be playing an important role in the toxicity of deltamethrin, allowing mosquitoes to rest on insecticide-treated materials despite treatment. These may have implications for the sustained efficacy of indoor residual spraying and insecticide-treated nets based control programmes that target indoor resting female mosquitoes of various gonotrophic status.
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Affiliation(s)
- Maxwell G Machani
- Climate and Human Health Research Unit, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
- School of Public Health and Community Development, Maseno University, Maseno, Kenya
| | - Eric Ochomo
- Entomology Section, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - David Sang
- School of Public Health and Community Development, Maseno University, Maseno, Kenya
| | - Mariangela Bonizzoni
- Department of Biology and Biotechnology, University of Pavia, 27100, Pavia, Italy
| | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California, Irvine, CA, 92697, USA
| | - Andrew K Githeko
- Climate and Human Health Research Unit, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California, Irvine, CA, 92697, USA
| | - Yaw A Afrane
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Accra, Ghana.
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Matiya DJ, Philbert AB, Kidima W, Matowo JJ. Dynamics and monitoring of insecticide resistance in malaria vectors across mainland Tanzania from 1997 to 2017: a systematic review. Malar J 2019; 18:102. [PMID: 30914051 PMCID: PMC6434877 DOI: 10.1186/s12936-019-2738-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/20/2019] [Indexed: 11/22/2022] Open
Abstract
Background Malaria still claims substantial lives of individuals in Tanzania. Insecticide-treated nets (ITNs) and indoor residual spray (IRS) are used as major malaria vector control tools. These tools are facing great challenges from the rapid escalating insecticide resistance in malaria vector populations. This review presents the information on the dynamics and monitoring of insecticide resistance in malaria vectors in mainland Tanzania since 1997. The information is important to policy-makers and other vector control stakeholders to reflect and formulate new resistance management plans in the country. Methods Reviewed articles on susceptibility and mechanisms of resistance in malaria vectors to insecticides across mainland Tanzania were systematically searched from the following databases: PubMed, Google scholar, HINARI and AGORA. The inclusion criteria were articles published between 2000 and 2017, reporting susceptibility of malaria vectors to insecticides, mechanisms of resistance in the mainland Tanzania, involving field collected adult mosquitoes, and mosquitoes raised from the field collected larvae. Exclusion criteria were articles reporting insecticide resistance in larval bio-assays, laboratory strains, and unpublished data. Reviewed information include year of study, malaria vectors, insecticides, and study sites. This information was entered in the excel sheet and analysed. Results A total of 30 articles met the selection criteria. The rapid increase of insecticide resistance in the malaria vectors across the country was reported since year 2006 onwards. Insecticide resistance in Anopheles gambiae sensu lato (s.l.) was detected in at least one compound in each class of all recommended insecticide classes. However, the Anopheles funestus s.l. is highly resistant to pyrethroids and DDT. Knockdown resistance (kdr) mechanism in An. gambiae s.l. is widely studied in the country. Biochemical resistance by detoxification enzymes (P450s, NSE and GSTs) in An. gambiae s.l. was also recorded. Numerous P450s genes associated with metabolic resistance were over transcribed in An. gambiae s.l. collected from agricultural areas. However, no study has reported mechanisms of insecticide resistance in the An. funestus s.l. in the country. Conclusion This review has shown the dynamics and monitoring of insecticide resistance in malaria vector populations across mainland Tanzanian. This highlights the need for devising improved control approaches of the malaria vectors in the country.
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Affiliation(s)
- Deokary Joseph Matiya
- Dar es Salaam University College of Education (DUCE), P.O. Box 2329, Dar es Salaam, Tanzania. .,University of Dar es Salaam (UDSM), P.O. Box 35064, Dar es Salaam, Tanzania.
| | - Anitha B Philbert
- University of Dar es Salaam (UDSM), P.O. Box 35064, Dar es Salaam, Tanzania
| | - Winifrida Kidima
- University of Dar es Salaam (UDSM), P.O. Box 35064, Dar es Salaam, Tanzania
| | - Johnson J Matowo
- Kilimanjaro Christian Medical University College (KCMUCo), P.O. Box 2240, Moshi, Tanzania
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Kweka E, Mahande A, Ouma J, Karanja W, Msangi S, Temba V, Lyaruu L, Himeidan Y. Novel Indoor Residual Spray Insecticide With Extended Mortality Effect: A Case of SumiShield 50WG Against Wild Resistant Populations of Anopheles arabiensis in Northern Tanzania. GLOBAL HEALTH: SCIENCE AND PRACTICE 2018; 6:758-765. [PMID: 30591581 PMCID: PMC6370354 DOI: 10.9745/ghsp-d-18-00213] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 11/13/2018] [Indexed: 12/14/2022]
Abstract
The new SumiShield 50WG insecticide, which possibly has longer duration of effectiveness than other indoor residual spray (IRS) formulations, has potential as an alternative IRS product for malaria vector control, particularly where resistance to other formulations has developed. Background: Resistance of malaria vectors to different classes of insecticides has been reported in malaria-endemic areas. Identifying new indoor residual spray (IRS) compounds that are effective against resistant vector populations is a high priority in managing insecticide resistance. Method: A biological efficacy trial was conducted in the field from August 2016 to February 2017 to determine the efficacy of SumiShield 50WG, a new insecticide class, against wild Anopheles arabiensis. Indoor surfaces of 20 houses in Mabogini ward in the rural district of Moshi in northern Tanzania were sprayed with SumiShield 50WG. Bio-efficacy monitoring was conducted monthly for 6 months after the spray application. In addition, susceptibility tests were conducted by exposing mosquitoes to papers treated with permethrin 0.75%, pirimiphos-methyl 0.25%, and clothianidin 2% (SumiShield 50WG). Representatives from each household included in the study were surveyed about possible side effects or problems faced since the spray. Regression probit analysis was used to calculate knock-down times while the chi-square test was used to compare the mortality effect for mosquitoes. Results: The SumiShield 50WG insecticide maintained optimal efficacy in the field setting for the duration of the 6-month study period, with 100% mortality of mosquitoes by 144 to 168 hours post-exposure to treated surfaces. Susceptibility tests showed some variation in tolerance to the tested insecticide-treated papers, particularly between SumiShield 50WG and pirimiphos-methyl. The knock-down times for 50% and 95% of the mosquitoes when exposed to SumiShield 50WG-treated test paper were 45.81 minutes and 83.85 minutes, respectively, and 67.77 minutes and 105.81 minutes, respectively, for the pirimiphos-methyl-treated papers. There were no short-term adverse side effects reported by households sprayed with SumiShield 50WG. Conclusion: The findings of this study suggest that SumiShield 50WG is a viable IRS insecticide for malaria vector control in Tanzania, especially in areas where pyrethroid resistance is a concern.
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Affiliation(s)
- Eliningaya Kweka
- Department of Medical Parasitology and Entomology, School of Medicine, Catholic University of Health and Allied Sciences, Mwanza, Tanzania. .,Mosquito Section, Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania
| | - Aneth Mahande
- Mabogini field station, Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, Moshi, Tanzania
| | - Johnson Ouma
- Africa Technical Research Centre, Vector Health International Ltd., Arusha, Tanzania
| | - Wycliffe Karanja
- Africa Technical Research Centre, Vector Health International Ltd., Arusha, Tanzania
| | - Shandala Msangi
- Mosquito Section, Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania
| | - Violet Temba
- Mosquito Section, Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania
| | - Lucille Lyaruu
- Mosquito Section, Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania
| | - Yousif Himeidan
- Africa Technical Research Centre, Vector Health International Ltd., Arusha, Tanzania
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Implications of insecticide resistance for malaria vector control with long-lasting insecticidal nets: trends in pyrethroid resistance during a WHO-coordinated multi-country prospective study. Parasit Vectors 2018; 11:550. [PMID: 30348209 PMCID: PMC6198431 DOI: 10.1186/s13071-018-3101-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 09/06/2018] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Increasing pyrethroid resistance has been an undesirable correlate of the rapid increase in coverage of insecticide-treated nets (ITNs) since 2000. Whilst monitoring of resistance levels has increased markedly over this period, longitudinal monitoring is still lacking, meaning the temporal and spatial dynamics of phenotypic resistance in the context of increasing ITN coverage are unclear. METHODS As part of a large WHO-co-ordinated epidemiological study investigating the impact of resistance on malaria infection, longitudinal monitoring of phenotypic resistance to pyrethroids was undertaken in 290 clusters across Benin, Cameroon, India, Kenya and Sudan. Mortality in response to pyrethroids in the major anopheline vectors in each location was recorded during consecutive years using standard WHO test procedures. Trends in mosquito mortality were examined using generalised linear mixed-effect models. RESULTS Insecticide resistance (using the WHO definition of mortality < 90%) was detected in clusters in all countries across the study period. The highest mosquito mortality (lowest resistance frequency) was consistently reported from India, in an area where ITNs had only recently been introduced. Substantial temporal and spatial variation was evident in mortality measures in all countries. Overall, a trend of decreasing mosquito mortality (increasing resistance frequency) was recorded (Odds Ratio per year: 0.79 per year (95% CI: 0.79-0.81, P < 0.001). There was also evidence that higher net usage was associated with lower mosquito mortality in some countries. DISCUSSION Pyrethroid resistance increased over the study duration in four out of five countries. Insecticide-based vector control may be compromised as a result of ever higher resistance frequencies.
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