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Parker JEA, Kakilla C, Nelwin K, Kroner C, Logan R, Ismail HM, Towers C, Manjurano A, Towers D, McCall PJ. Video-tracked Anopheles arabiensis entry and exit behaviour at washed and damaged pyrethroid-treated bednets. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231165. [PMID: 39076790 PMCID: PMC11285834 DOI: 10.1098/rsos.231165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 04/03/2024] [Accepted: 04/05/2024] [Indexed: 07/31/2024]
Abstract
Insecticide-treated nets (ITNs) are the most effective method for malaria prevention in Africa. Using near-infrared video tracking in a laboratory environment, we recorded and assessed bednet entry and exit by a northern Tanzanian population of Anopheles arabiensis at a human-occupied untreated net and a PermaNet® 2.0 ITN. Both had 12 holes, each 10 cm in diameter, punctured at specific locations, and the ITN was washed 20 times to further simulate the wear and tear of ageing. Washing reduced the insecticide content of ITNs by 61%, which then showed similar rates to the untreated nets for net entry (39% entered untreated net and 41% entered ITN; p = 0.84) and exit (37% and 43%, respectively; p = 0.67). Regardless of treatment, approximately 40% of mosquitoes entered nets within 20 s of first appearing in the field of view and reached the volunteer's skin within 5 s of entering the net. Mortality rates post-exposure were significantly higher (p = 0.048) at ITNs (26.6%; 95% CI 13.4%-39.7%) than at untreated controls (6.4%; 95% CI 1.8%-14.6%). The washed and aged ITN provided little additional personal protection for the sleeper over an untreated net. Simple adjustments to materials and design that could extend the effective lifespan of ITNs are discussed.
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Affiliation(s)
- J. E. A. Parker
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - C. Kakilla
- National Institute of Medical Research, Mwanza, Tanzania
| | - K. Nelwin
- National Institute of Medical Research, Mwanza, Tanzania
| | - C. Kroner
- School of Engineering, University of Warwick, Coventry, UK
| | - R. Logan
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- Parasitology Department, Heidelberg University Hospital, Heidelberg, Germany
| | - H. M. Ismail
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - C. Towers
- School of Engineering, University of Warwick, Coventry, UK
| | - A. Manjurano
- National Institute of Medical Research, Mwanza, Tanzania
| | - D. Towers
- School of Engineering, University of Warwick, Coventry, UK
| | - P. J. McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
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Wheldrake A, Guillemois E, Arouni H, Chetty V, Zappa E, Russell SJ. Physical durability: are bed nets getting any stronger? Malar J 2024; 23:19. [PMID: 38218962 PMCID: PMC10787957 DOI: 10.1186/s12936-023-04832-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 12/29/2023] [Indexed: 01/15/2024] Open
Abstract
BACKGROUND For at least a decade, concerns have been raised about the physical durability of insecticide-treated nets (ITNs) and their ability to remain in good condition for at least three years. To discover if the resistance to damage (RD) of ITNs has improved or not, the RD scores of ITNs sampled in 2013 and 2020 were compared. METHODS The RD scores and disaggregated textile performance data for nine ITNs recommended by the WHO pesticide evaluation scheme (WHOPES) measured in 2013 were compared with WHO-prequalified ITNs sampled in 2020. This included assessment of newer ITNs not available in 2013, to determine the extent to which product development has led to performance improvements across all available ITNs in the intervening years. RESULTS The resistance to damage of ITNs has not generally improved from 2013 to 2020, and in some cases performance is worse. The average RD score of comparable ITNs brands decreased from 40 in 2013 to 36 in 2020. Of the nets available in 2020, only two of the twenty-four ITN products tested achieved an RD score of > 50, while six ITNs had very low RD scores of < 30, highlighting a serious inherent, and literal weakness in many WHO-prequalified ITNs. CONCLUSIONS The long-term physical durability of ITN products cannot be expected to improve while their resistance to damage remains so low, and major upgrades to the performance standards of textile materials used to make ITNs, as well as incentives to develop stronger ones are urgently required.
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Affiliation(s)
- Amy Wheldrake
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK
| | - Estelle Guillemois
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK
| | - Hamidreza Arouni
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK
| | - Vera Chetty
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK
| | - Edoardo Zappa
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK
| | - Stephen J Russell
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK.
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Mbuba E, Odufuwa OG, Moore J, Mmbaga S, Tchicaya E, Edi C, Chalageri V, Uragayala S, Sharma A, Rahi M, Raghavendra K, Eapen A, Koenker H, Ross A, Moore SJ. Multi-country evaluation of the durability of pyrethroid plus piperonyl-butoxide insecticide-treated nets: study protocol. Malar J 2023; 22:30. [PMID: 36707886 PMCID: PMC9881340 DOI: 10.1186/s12936-023-04465-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 01/20/2023] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Mass distributions of long-lasting insecticidal nets (LLINs) have contributed to large reductions in the malaria burden. However, this success is in jeopardy due in part to the increasing pyrethroid-resistant mosquito population as well as low LLINs coverage in various areas because the lifespan of LLINs is often shorter than the interval between replenishment campaigns. New insecticide-treated nets (ITNs) containing pyrethroid and piperonyl-butoxide (PBO) have shown a greater reduction in the incidence of malaria than pyrethroid LLINs in areas with pyrethroid-resistant mosquitoes. However, the durability (attrition, bio-efficacy, physical integrity and chemical retainment) of pyrethroid-PBO ITNs under operational settings has not been fully characterized. This study will measure the durability of pyrethroid-PBO ITNs to assess whether they meet the World Health Organization (WHO) three years of operational performance criteria required to be categorized as "long-lasting". METHODS A prospective household randomized controlled trial will be conducted simultaneously in Tanzania, India and Côte d'Ivoire to estimate the field durability of three pyrethroid-PBO ITNs (Veeralin®, Tsara® Boost, and Olyset® Plus) compared to a pyrethroid LLIN: MAGNet®. Durability monitoring will be conducted up to 36 months post-distribution and median survival in months will be calculated. The proportion of ITNs: (1) lost (attrition), (2) physical integrity, (3) resistance to damage score, (4) meeting WHO bio-efficacy (≥ 95% knockdown after 1 h or ≥ 80% mortality after 24 h for WHO cone bioassay, or ≥ 90% blood-feeding inhibition or ≥ 80% mortality after 24 h for WHO Tunnel tests) criteria against laboratory-reared resistant and susceptible mosquitoes, and insecticidal persistence over time will be estimated. The non-inferiority of Veeralin® and Tsara® Boost to the first-in-class, Olyset® Plus will additionally be assessed for mortality, and the equivalence of 20 times washed ITNs compared to field aged ITNs will be assessed for mortality and blood-feeding inhibition endpoints in the Ifakara Ambient Chamber Test, Tanzania. CONCLUSION This will be the first large-scale prospective household randomized controlled trial of pyrethroid-PBO ITNs in three different countries in East Africa, West Africa and South Asia, simultaneously. The study will generate information on the replenishment intervals for PBO nets.
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Affiliation(s)
- Emmanuel Mbuba
- grid.414543.30000 0000 9144 642XVector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania ,grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, St. Petersplatz 1, 4002 Basel, Switzerland
| | - Olukayode G. Odufuwa
- grid.414543.30000 0000 9144 642XVector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania ,grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, St. Petersplatz 1, 4002 Basel, Switzerland ,grid.8991.90000 0004 0425 469XEpidemiology and Population Health Department, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT UK
| | - Jason Moore
- grid.414543.30000 0000 9144 642XVector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania ,grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland
| | - Selemani Mmbaga
- grid.414543.30000 0000 9144 642XVector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | - Emile Tchicaya
- grid.462846.a0000 0001 0697 1172Swiss Centre for Scientific Research in Côte d’Ivoire, 1303 Abidjan, Côte d’Ivoire ,Vegro Aps, Copenhagen, Denmark Refshalevej 213A,
| | - Constant Edi
- grid.462846.a0000 0001 0697 1172Swiss Centre for Scientific Research in Côte d’Ivoire, 1303 Abidjan, Côte d’Ivoire
| | - Vani Chalageri
- grid.419641.f0000 0000 9285 6594Field Unit, ICMR-National Institute of Malaria Research, Bangalore, Karnataka India
| | - Sreehari Uragayala
- grid.419641.f0000 0000 9285 6594Field Unit, ICMR-National Institute of Malaria Research, Bangalore, Karnataka India
| | - Amit Sharma
- grid.419641.f0000 0000 9285 6594ICMR-National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077 India
| | - Manju Rahi
- grid.19096.370000 0004 1767 225XICMR-Indian Council of Medical Research, Ansari Nagar, New Delhi, India
| | - Kamaraju Raghavendra
- grid.419641.f0000 0000 9285 6594ICMR-National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077 India
| | - Alex Eapen
- grid.19096.370000 0004 1767 225XField Unit, ICMR-Indian Council of Medical Research, Chennai, India
| | | | - Amanda Ross
- grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, St. Petersplatz 1, 4002 Basel, Switzerland
| | - Sarah J. Moore
- grid.414543.30000 0000 9144 642XVector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania ,grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, St. Petersplatz 1, 4002 Basel, Switzerland
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Brake S, Gomez-Maldonado D, Hummel M, Zohdy S, Peresin MS. Understanding the current state-of-the-art of long-lasting insecticide nets and potential for sustainable alternatives. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2022; 2:100101. [PMID: 36248356 PMCID: PMC9562956 DOI: 10.1016/j.crpvbd.2022.100101] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 11/23/2022]
Abstract
Long-lasting insecticide-treated nets (LLINs) are widely distributed to communities where malaria is a major cause of mortality, especially to those under the age of 5 years-old. To protect people from this illness, LLINs provide physical and chemical barriers by containing insecticides within the matrix of the polymer fibers or on the surface. Synthetic polymers including polyethylene and polyester are common material choices for these nets, and pyrethroids, along with other additives, are the insecticides of choice for this application. Many studies have shown the effectiveness of these nets on the impact of malaria is highly significant, but there is a demand for more durable nets that last longer than only a few years as the available products are rated for 2–3 years of use. Improvements in this area would increase cost effectiveness, because better durability would reduce the frequency of manufacturing and worldwide shipping. Additionally, due to the plastic fibers, the waste can build quickly, damaging the environment. To deal with the sustainability and durability issues, biodegradable and renewable materials should be chosen as an alternative. LLINs are important for malaria control, but they require a sustainable and durable alternative to synthetic polymers. LLINs are made by extrusion of pyrethroids and synthetic polymers or by coating. The current LLINs include important active ingredients to improve insecticidal activity. Bio-based polymers have the potential to be used to develop a superior LLIN to those available currently.
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Mbwambo SG, Bubun N, Mbuba E, Moore J, Mbina K, Kamande D, Laman M, Mpolya E, Odufuwa OG, Freeman T, Karl S, Moore SJ. Comparison of cone bioassay estimates at two laboratories with different Anopheles mosquitoes for quality assurance of pyrethroid insecticide-treated nets. Malar J 2022; 21:214. [PMID: 35799172 PMCID: PMC9264565 DOI: 10.1186/s12936-022-04217-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 06/11/2022] [Indexed: 11/16/2022] Open
Abstract
Background Quality assurance (QA) of insecticide-treated nets (ITNs) delivered to malaria-endemic countries is conducted by measuring physiochemical parameters, but not bioefficacy against malaria mosquitoes. This study explored utility of cone bioassays for pre-delivery QA of pyrethroid ITNs to test the assumption that cone bioassays are consistent across locations, mosquito strains, and laboratories. Methods Double-blinded bioassays were conducted on twenty unused pyrethroid ITNs of 4 brands (100 nets, 5 subsamples per net) that had been delivered for mass distribution in Papua New Guinea (PNG) having passed predelivery inspections. Cone bioassays were performed on the same net pieces following World Health Organization (WHO) guidelines at the PNG Institute of Medical Research (PNGIMR) using pyrethroid susceptible Anopheles farauti sensu stricto (s.s.) and at Ifakara Health Institute (IHI), Tanzania using pyrethroid susceptible Anopheles gambiae s.s. Additionally, WHO tunnel tests were conducted at IHI on ITNs that did not meet cone bioefficacy thresholds. Results from IHI and PNGIMR were compared using Spearman’s Rank correlation, Bland–Altman (BA) analysis and analysis of agreement. Literature review on the use of cone bioassays for unused pyrethroid ITNs testing was conducted. Results In cone bioassays, 13/20 nets (65%) at IHI and 8/20 (40%) at PNGIMR met WHO bioefficacy criteria. All nets met WHO bioefficacy criteria on combined cone/tunnel tests at IHI. Results from IHI and PNGIMR correlated on 60-min knockdown (KD60) (rs = 0.6,p = 0.002,n = 20) and 24-h mortality (M24) (rs = 0.9,p < 0.0001,n = 20) but BA showed systematic bias between the results. Of the 5 nets with discrepant result between IHI and PNGIMR, three had confidence intervals overlapping the 80% mortality threshold, with averages within 1–3% of the threshold. Including these as a pass, the agreement between the results to predict ITN failure was good with kappa = 0.79 (0.53–1.00) and 90% accuracy. Conclusions Based on these study findings, the WHO cone bioassay is a reproducible bioassay for ITNs with > 80% M24, and for all ITNs provided inherent stochastic variation and systematic bias are accounted for. The literature review confirms that WHO cone bioassay bioefficacy criteria have been previously achieved by all pyrethroid ITNs (unwashed), without the need for additional tunnel tests. The 80% M24 threshold remains the most reliable indicator of pyrethroid ITN quality using pyrethroid susceptible mosquitoes. In the absence of alternative tests, cone bioassays could be used as part of pre-delivery QA.
Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04217-3.
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Affiliation(s)
- Stephen G Mbwambo
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania. .,Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania. .,Sokoine RRH, Ministry of Health, Lindi, Tanzania. .,Regional Health Management Team, P.O Box 1011, Lindi, Tanzania.
| | - Nakei Bubun
- Vector Borne Disease Unit, PNG Institute of Medical Research, Madang Province 511, P.O Box 378, Madang, Papua New Guinea
| | - Emmanuel Mbuba
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,University of Basel, Basel, Switzerland.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland
| | - Jason Moore
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland
| | - Kasiani Mbina
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania
| | - Dismas Kamande
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania
| | - Moses Laman
- Vector Borne Disease Unit, PNG Institute of Medical Research, Madang Province 511, P.O Box 378, Madang, Papua New Guinea
| | - Emmanuel Mpolya
- Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania
| | - Olukayode G Odufuwa
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,University of Basel, Basel, Switzerland.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland.,MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Tim Freeman
- Rotarian Against Malaria, P.O Box 3686, Boroko, NCD 111, Papua New Guinea
| | - Stephan Karl
- Vector Borne Disease Unit, PNG Institute of Medical Research, Madang Province 511, P.O Box 378, Madang, Papua New Guinea.,Australian Institute of Tropical Health and Medicine, James Cook University, 1/14-88 McGregor Road, Smithfield, QLD, 4870, Australia
| | - Sarah J Moore
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania.,University of Basel, Basel, Switzerland.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland
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Maps and metrics of insecticide-treated net access, use, and nets-per-capita in Africa from 2000-2020. Nat Commun 2021; 12:3589. [PMID: 34117240 PMCID: PMC8196080 DOI: 10.1038/s41467-021-23707-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 05/12/2021] [Indexed: 02/05/2023] Open
Abstract
Insecticide-treated nets (ITNs) are one of the most widespread and impactful malaria interventions in Africa, yet a spatially-resolved time series of ITN coverage has never been published. Using data from multiple sources, we generate high-resolution maps of ITN access, use, and nets-per-capita annually from 2000 to 2020 across the 40 highest-burden African countries. Our findings support several existing hypotheses: that use is high among those with access, that nets are discarded more quickly than official policy presumes, and that effectively distributing nets grows more difficult as coverage increases. The primary driving factors behind these findings are most likely strong cultural and social messaging around the importance of net use, low physical net durability, and a mixture of inherent commodity distribution challenges and less-than-optimal net allocation policies, respectively. These results can inform both policy decisions and downstream malaria analyses.
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Wheldrake A, Guillemois E, Chetty V, Kilian A, Russell SJ. Development of a single resistance to damage metric for mosquito nets related to physical integrity in the field. Malar J 2021; 20:46. [PMID: 33468151 PMCID: PMC7816509 DOI: 10.1186/s12936-020-03566-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 12/22/2020] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND In common with the majority of personal protective equipment and healthcare products, the ability for long-lasting insecticidal nets (LLINs) to remain in good physical condition during use is a key factor governing fitness for purpose and serviceability. The inherent ability of a product to resist physical deterioration should be known in advance of it being used to ensure it has maximum value to both the end-user and procurer. The objective of this study was to develop a single performance metric of resistance to damage (RD) that can be applied to any LLIN product prior to distribution. METHODS Algorithms to calculate RD values were developed based on consideration of both human factors and laboratory testing data. Quantitative reference forces applied to LLINs by users during normal use were determined so that aspirational performance levels could be established. The ability of LLINs to resist mechanical damage was assessed based on a new suite of textile tests, reflecting actual mechanisms of physical deterioration during normal household use. These tests quantified the snag strength, bursting strength, abrasion resistance and resistance to hole enlargement. Sixteen different unused LLINs were included in the analysis. The calculated RD values for all LLINs and the corresponding physical integrity data for the same nets retrieved from the field (up to 3 years of use) were then compared. RESULTS On a RD scale of 0 (lowest resistance) - 100 (highest resistance), only six of the sixteen LLINs achieved an RD value above 50. No current LLIN achieved the aspirational level of resistance to damage (RD = 100), suggesting that product innovation is urgently required to increase the RD of LLINs. LLINs with higher RD values were associated with lower hole damage (PHI) in the field when adjusted for normal use conditions. CONCLUSIONS The RD value of any LLIN product can be determined prior to distribution based on the developed algorithms and laboratory textile testing data. Generally, LLINs need to achieve higher RD values to improve their ability to resist hole formation during normal use. Innovation in LLIN product design focused on the textile material should be actively encouraged and is urgently needed to close the performance gap.
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Affiliation(s)
- Amy Wheldrake
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | - Estelle Guillemois
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | - Vera Chetty
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | | | - Stephen J Russell
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK.
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