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Tungu PK, Sudi W, Kisinza W, Rowland M. Effectiveness of a long-lasting insecticide treatment kit (ICON® Maxx) for polyester nets over three years of household use: a WHO phase III trial in Tanzania. Malar J 2021; 20:345. [PMID: 34412651 PMCID: PMC8375204 DOI: 10.1186/s12936-021-03871-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 08/03/2021] [Indexed: 11/23/2022] Open
Abstract
Background ICON® Maxx (Syngenta) is an insecticide treatment kit of pyrethroid and binding agent for long-lasting treatment of mosquito nets. Interim recommendation for use on nets was granted by the World Health Organization (WHO) after successful evaluation in experimental huts following multiple washes. A full WHO recommendation is contingent upon demonstration of continued bio-efficacy after 3 years of use. Methods A household-randomized prospective study design was used to assess ICON Maxx-treated nets over 3 years in north-eastern Tanzania. Conventional treated nets (with lambda-cyhalothrin, but without binder) served as a positive control. At 6-monthly intervals, cross-sectional household surveys monitored net use and physical integrity, while cone and tunnel tests assessed insecticidal efficacy. Pyrethroid content was determined after 12 and 36 months. A parallel cohort of nets was monitored annually for evidence of net deterioration and attrition. Results After 12 months’ use, 97% of ICON Maxx-treated nets but only 67% of CTN passed the WHO efficacy threshold for insecticidal durability (> 80% mortality in cone or tunnel or 90% feeding inhibition in tunnel). After 24- and 36-months use, 67% and 26% of ICON Maxx treated nets met the cone criteria, respectively, and over 90% met the combined cone and tunnel criteria. Lambda-cyhalothrin content after 36 months was 17% (15.8 ± 4.3 mg/m2) of initial content. ICON Maxx nets were used year-round and washed approximately 4 times per year. In cross-sectional survey after 36 months the average number of holes was 20 and hole index was 740 cm2 per net. Cohort nets had fewer holes and smaller hole index than cross-sectional nets. However, only 15% (40/264) of cohort nets were not lost to follow-up or not worn out after 36 months. Conclusions Because more than 80% of nets met the WHO efficacy criteria after 36 months use, ICON Maxx was granted WHO full recommendation. Cross-sectional and cohort surveys were complementary and gave a fuller understanding of net durability. To improve net usage and retention, stronger incentives and health messaging should be introduced in WHO LLIN longitudinal trials. Untreated polyester nets may be made long-lastingly insecticidal in Africa through simple household treatment using ICON Maxx pyrethroid-binder kits.
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Affiliation(s)
- Patrick K Tungu
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania. .,Pan-African Malaria Vector Research Consortium (PAMVERC), PO Box 81, Muheza, Tanga, Tanzania.
| | - Wema Sudi
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania.,Pan-African Malaria Vector Research Consortium (PAMVERC), PO Box 81, Muheza, Tanga, Tanzania
| | - William Kisinza
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania.,Pan-African Malaria Vector Research Consortium (PAMVERC), PO Box 81, Muheza, Tanga, Tanzania
| | - Mark Rowland
- Pan-African Malaria Vector Research Consortium (PAMVERC), PO Box 81, Muheza, Tanga, Tanzania.,London School of Hygiene and Tropical Medicine, London, UK
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Nyangi M, Kigondu E, Irungu B, Nganga M, Gachanja A, Murigi M, Nyangacha R, Muniu E, Kamau L, Gathirwa J. Integrity, use and care of long-lasting insecticidal nets in Kirinyaga County, Kenya. BMC Public Health 2021; 21:856. [PMID: 33941135 PMCID: PMC8091527 DOI: 10.1186/s12889-021-10882-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 04/21/2021] [Indexed: 11/21/2022] Open
Abstract
Background Vector control is an essential component in prevention and control of malaria in malaria endemic areas. Insecticide treated nets is one of the standard tools recommended for malaria vector control. The objective of the study was to determine physical integrity and insecticidal potency of long-lasting insecticidal nets (LLINs) used in control of malaria vector in Kirinyaga County, Kenya. Method The study targeted households in an area which had received LLINs during mass net distribution in 2016 from Ministry of Health. A total of 420 households were sampled using systematic sampling method, where the household heads consented to participate in the study. A semi-structured questionnaire was administered to assess care and use while physical examination was used to determine integrity. Chemical concentration was determined by gas chromatography mass spectroscopy (GC-MS). Data analysis was done using Statistical Package for Social Sciences (SPSS) version 19. Results After 18 months of use, 96.9% (95% CI: 95.2–98.6%) of the distributed nets were still available. Regarding net utilization, 94.1% of household heads reported sleeping under an LLIN the previous night. After physical examination, 49.9% (95% CI: 43–52.8%) of the bed nets had at least one hole. The median number of holes of any size was 2[interquartile range (IQR) 1–4], and most holes were located on the lower part of the nets, [median 3 (IQR 2–5)]. Only 15% of the nets with holes had been repaired. The median concentration for α-cypermethrin was 7.15 mg/m2 (IQR 4.25–15.31) and 0.00 mg/g (IQR 0.00–1.99) for permethrin. Based on pHI, Chi-square test varied significantly with the manufacturer (X (6, N = 389) = 29.14, p = 0.04). There was no significant difference between nets with different number of washes (X2(2) = 4.55, p = 0.103). Conclusion More than three-quarters of the nets supplied had survived and insecticidal potency was adequate in vector control. Standard procedure for field evaluation of surface insecticidal content available to a mosquito after landing on a net to rest is recommended. Supplementary Information The online version contains supplementary material available at 10.1186/s12889-021-10882-x.
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Affiliation(s)
- Mary Nyangi
- Department of Chemistry, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya.
| | - Elizabeth Kigondu
- Centre for Traditional Medicine and Drug Research, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Beatrice Irungu
- Centre for Traditional Medicine and Drug Research, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Margaret Nganga
- Department of Chemistry, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya
| | - Anthony Gachanja
- Department of Chemistry, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya
| | - Martin Murigi
- Department of Chemistry, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya
| | - Ruth Nyangacha
- Centre for Traditional Medicine and Drug Research, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Erastus Muniu
- Centre for Public Health and Research, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Luna Kamau
- Centre for Biotechnology, Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Jeremiah Gathirwa
- Centre for Traditional Medicine and Drug Research, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
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Tungu PK, Michael E, Sudi W, Kisinza WW, Rowland M. Efficacy of interceptor® G2, a long-lasting insecticide mixture net treated with chlorfenapyr and alpha-cypermethrin against Anopheles funestus: experimental hut trials in north-eastern Tanzania. Malar J 2021; 20:180. [PMID: 33836778 PMCID: PMC8033724 DOI: 10.1186/s12936-021-03716-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 03/27/2021] [Indexed: 11/23/2022] Open
Abstract
Background The effectiveness of long-lasting insecticidal nets (LLIN), the primary method for preventing malaria in Africa, is compromised by evolution and spread of pyrethroid resistance. Further gains require new insecticides with novel modes of action. Chlorfenapyr is a pyrrole insecticide that disrupts mitochrondrial function and confers no cross-resistance to neurotoxic insecticides. Interceptor® G2 LN (IG2) is an insecticide-mixture LLIN, which combines wash-resistant formulations of chlorfenapyr and the pyrethroid alpha-cypermethrin. The objective was to determine IG2 efficacy under controlled household-like conditions for personal protection and control of wild, pyrethroid-resistant Anopheles funestus mosquitoes. Methods Experimental hut trials tested IG2 efficacy against two positive controls—a chlorfenapyr-treated net and a standard alpha-cypermethrin LLIN, Interceptor LN (IG1)—consistent with World Health Organization (WHO) evaluation guidelines. Mosquito mortality, blood-feeding inhibition, personal protection, repellency and insecticide-induced exiting were recorded after zero and 20 washing cycles. The trial was repeated and analysed using multivariate and meta-analysis. Results In the two trials held in NE Tanzania, An. funestus mortality was 2.27 (risk ratio 95% CI 1.13–4.56) times greater with unwashed Interceptor G2 than with unwashed Interceptor LN (p = 0.012). There was no significant loss in mortality with IG2 between 0 and 20 washes (1.04, 95% CI 0.83–1.30, p = 0.73). Comparison with chlorfenapyr treated net indicated that most mortality was induced by the chlorfenapyr component of IG2 (0.96, CI 0.74–1.23), while comparison with Interceptor LN indicated blood-feeding was inhibited by the pyrethroid component of IG2 (IG2: 0.70, CI 0.44–1.11 vs IG1: 0.61, CI 0.39–0.97). Both insecticide components contributed to exiting from the huts but the contributions were heterogeneous between trials (heterogeneity Q = 36, P = 0.02). WHO susceptibility tests with pyrethroid papers recorded 44% survival in An. funestus. Conclusions The high mortality recorded by IG2 against pyrethroid-resistant An. funestus provides first field evidence of high efficacy against this primary, anthropophilic, malaria vector.
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Affiliation(s)
- Patrick K Tungu
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania. .,Pan-African Malaria Vector Research Consortium (PAMVERC), P.O.Box 81, Muheza, Tanga, Tanzania.
| | - Elisante Michael
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania.,Pan-African Malaria Vector Research Consortium (PAMVERC), P.O.Box 81, Muheza, Tanga, Tanzania
| | - Wema Sudi
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania.,Pan-African Malaria Vector Research Consortium (PAMVERC), P.O.Box 81, Muheza, Tanga, Tanzania
| | - William W Kisinza
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania.,Pan-African Malaria Vector Research Consortium (PAMVERC), P.O.Box 81, Muheza, Tanga, Tanzania
| | - Mark Rowland
- Pan-African Malaria Vector Research Consortium (PAMVERC), P.O.Box 81, Muheza, Tanga, Tanzania.,London School of Hygiene and Tropical Medicine, London, UK
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Mosha JF, Kulkarni MA, Messenger LA, Rowland M, Matowo N, Pitt C, Lukole E, Taljaard M, Thickstun C, Manjurano A, Mosha FW, Kleinschmidt I, Protopopoff N. Protocol for a four parallel-arm, single-blind, cluster-randomised trial to assess the effectiveness of three types of dual active ingredient treated nets compared to pyrethroid-only long-lasting insecticidal nets to prevent malaria transmitted by pyrethroid insecticide-resistant vector mosquitoes in Tanzania. BMJ Open 2021; 11:e046664. [PMID: 34006037 PMCID: PMC7942254 DOI: 10.1136/bmjopen-2020-046664] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 01/21/2021] [Accepted: 02/15/2021] [Indexed: 01/21/2023] Open
Abstract
INTRODUCTION The massive scale-up of long-lasting insecticidal nets (LLINs) has led to major reductions in malaria burden in many sub-Saharan African countries. This progress is threatened by widespread insecticide resistance among malaria vectors. This cluster-randomised controlled trial (c-RCT) compares three of the most promising dual active ingredients LLINs (dual-AI LLINs), which incorporate mixtures of insecticides or insecticide synergists to standard LLINs in an area of pyrethroid insecticide resistance. METHODS A four-arm, single-blinded, c-RCT will evaluate the effectiveness of three types of dual-AI LLINs (1) Royal Guard, combining two insecticides, pyriproxyfen and the pyrethroid alpha-cypermethrin; (2) Interceptor G2, combining chlorfenapyr and alpha-cypermethrin; (3) Olyset Plus, an LLIN combining a synergist, piperonyl butoxide and the pyrethroid permethrin, compared with; (4) Interceptor LN, a standard LLIN containing the pyrethroid alpha-cypermethrin as the sole AI. The primary outcomes are malaria infection prevalence in children aged 6 months-14 years and entomological inoculation rate (EIR), as a standard measure of malaria transmission at 24 months postintervention and cost-effectiveness. ETHICS AND DISSEMINATION Ethical approval was received from the institutional review boards of the Tanzanian National Institute for Medical Research, Kilimanjaro Christian Medical University College, London School of Hygiene and Tropical Medicine, and University of Ottawa. Study findings will be actively disseminated via reports and presentations to stakeholders, local community leaders, and relevant national and international policy makers as well as through conferences, and peer-reviewed publications. TRIAL REGISTRATION NUMBER NCT03554616.
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Affiliation(s)
- Jacklin F Mosha
- Parasitology, National Institute for Medical Research Mwanza Research Centre, Mwanza, United Republic of Tanzania
| | - Manisha A Kulkarni
- Epidemiology & Public Health, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
| | - Louisa A Messenger
- Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Mark Rowland
- Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Nancy Matowo
- Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Catherine Pitt
- Global Health and Development, London School of Hygiene & Tropical Medicine, London, UK
| | - Eliud Lukole
- Parasitology, National Institute for Medical Research Mwanza Research Centre, Mwanza, United Republic of Tanzania
- Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Monica Taljaard
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Charles Thickstun
- Epidemiology & Public Health, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
| | - Alphaxard Manjurano
- Parasitology, National Institute for Medical Research Mwanza Research Centre, Mwanza, United Republic of Tanzania
| | - Franklin W Mosha
- Parasitology, Kilimanjaro Christian Medical University College, Moshi, United Republic of Tanzania
| | - Immo Kleinschmidt
- Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
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de Araújo Barbosa V, de Souza CF, Pereira A, Gatherer D, Brazil RP, Bray DP, Hamilton JG. Insecticide-impregnated netting: A surface treatment for killing Lutzomyia longipalpis (Diptera: Psychodidae), the vector of Leishmania infantum. Current Research in Parasitology & Vector-Borne Diseases 2021; 1:None. [PMID: 35005688 PMCID: PMC8716342 DOI: 10.1016/j.crpvbd.2021.100044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/01/2021] [Accepted: 07/19/2021] [Indexed: 12/04/2022]
Abstract
The sand fly Lutzomyia longipalpis is the main vector of Leishmania infantum in Brazil. Synthetic male-produced sex/aggregation pheromone co-located with micro-encapsulated λ-cyhalothrin in chicken sheds can significantly reduce canine infection and sand fly densities in a lure-and-kill strategy. In this study, we determined if insecticide-impregnated netting (IN) could replace insecticide residual spraying (IRS). We compared numbers of Lu. longipalpis attracted and killed in experimental and real chicken sheds baited with pheromone and treated with a 1 m2 area of either insecticide spray or netting. First, we compared both treatments in experimental sheds to control mortality established from light trap captures. We then compared the long-term killing effect of insecticide spray and netting, without renewal, in experimental sheds over a period of 16 weeks. Finally, a longitudinal intervention study in real chicken sheds compared the numbers and proportions of Lu. longipalpis collected and killed before and after application of both treatments. In Experiment 1, a higher proportion of males and females captured in IRS- and IN-treated sheds were dead at 24 h compared to controls (P < 0.05). No difference was found in the proportion of females killed in sheds treated with IN or IRS (P = 0.15). A slightly higher proportion of males were killed by IRS (100%) compared to IN (98.6%; P < 0.05). In Experiment 2, IN- and IRS-treated traps were equally effective at killing females (P = 0.21) and males (P = 0.08). However, IRS killed a significantly higher proportion of females and males after 8 (P < 0.05) and 16 (P < 0.05) weeks. In Experiment 3, there was no significant difference between treatments in the proportion of females killed before (P = 0.88) or after (P = 0.29) or males killed before (P = 0.76) or after (P = 0.73) intervention. Overall, initially the IN was as effective as IRS at killing female and male Lu. longipalpis in both experimental and real chicken sheds. However, the relative lethal effect of the IN deteriorated over time when stored under prevailing environmental conditions. Chicken sheds treated with netting or spray insecticide killed Lutzomyia longipalpis. Same effect was seen in experimental and real chicken sheds. Netting was as effective as spraying insecticide initially. Sprayed insecticide killed a higher proportion of both sexes after 8 and 16 weeks. The relative lethal effect of the netting deteriorated over time.
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N’Guessan R, Odjo A, Ngufor C, Malone D, Rowland M. A Chlorfenapyr Mixture Net Interceptor® G2 Shows High Efficacy and Wash Durability against Resistant Mosquitoes in West Africa. PLoS One 2016; 11:e0165925. [PMID: 27851828 PMCID: PMC5112870 DOI: 10.1371/journal.pone.0165925] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 09/22/2016] [Indexed: 11/18/2022] Open
Abstract
Background Malaria control through use of long-lasting insecticidal nets (LN) is threatened by the selection of anopheline mosquitoes strongly resistant to pyrethroid insecticides. To sustain future effectiveness it is essential to identify and evaluate novel insecticides suitable for nets. Mixtures of two insecticides with contrasting mode of action have the potential to kill resistant vectors and restore transmission control provided the formulation can withstand regular washing over the net’s life span. Method The efficacy of a novel mixture LN, Interceptor® G2, that combines the pyrrole chlorfenapyr and pyrethroid alpha-cypermethrin was evaluated under controlled household conditions (experimental hut trial) and by laboratory bioassay against pyrethroid resistant An. gambiae in Benin before and after standardized washing. Comparison arms included standard alpha-cypermethrin LN, nets hand-treated with chlorfenapyr-only and untreated nets. Results The chlorfenapyr-alphacypermethrin LN demonstrated improved efficacy and wash resistance compared to a standard alpha-cypermethrin LN against pyrethroid resistant mosquitoes (resistance ratio 207). In experimental hut trial alpha-cypermethrin LN killed only 20% (95% CI 15–26%) of host-seeking An. gambiae whilst mixture LN killed 71% (95% CI 65–77%). Mixture LN washed 20 times killed 65% (95% CI 58–71%), and thus intensive washing reduced efficacy by only 6% (95% CI 1.3–11%). The chlorfenapyr net killed 76% (95% CI 70–81%). Personal protection and blood feeding inhibition did not differ between mixture and pyrethroid LN; however, the mixture LN was 2.5 (95% CI: 2.1–3.1) times more protective than untreated nets. Standard WHO cone bioassays conducted during day time hours failed to anticipate field efficacy but overnight tunnel tests successfully predicted mixture LN and chlorfenapyr net efficacy in field trials. Conclusion Interceptor® G2 LN demonstrates the potential to control transmission and provide community protection over the normal lifespan of long lasting nets where standard pyrethroid LN show signs of failing due to resistance.
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Affiliation(s)
- Raphael N’Guessan
- London School of Hygiene and Tropical Medicine, London, United Kingdom
- Centre de Recherche Entomologique de Cotonou, Ministry of Health, Cotonou, Benin
- Pan-African Malaria Vector Research Consortium (PAMVERC), London, United Kingdom
| | - Abibatou Odjo
- Centre de Recherche Entomologique de Cotonou, Ministry of Health, Cotonou, Benin
| | - Corine Ngufor
- London School of Hygiene and Tropical Medicine, London, United Kingdom
- Centre de Recherche Entomologique de Cotonou, Ministry of Health, Cotonou, Benin
- Pan-African Malaria Vector Research Consortium (PAMVERC), London, United Kingdom
| | - David Malone
- Innovative Vector Control Consortium, Liverpool, United Kingdom
| | - Mark Rowland
- London School of Hygiene and Tropical Medicine, London, United Kingdom
- Pan-African Malaria Vector Research Consortium (PAMVERC), London, United Kingdom
- * E-mail:
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