Evaluation on the bioefficacy of PermaNet® 2.0, a long lasting net against Anopheles stephensi

Bagheri, Akbar; Vatandoost, Hassan; Shayeghi, M; Abai, Mohammad Reza; Ahmad, Rasheed; Godwin, Nutifafa Gidiglo; Akbari, Mohammad; Sheikhi, Soraya

doi:10.12980/apjtd.7.2017d6-368

Cited by 7 publications

(13 citation statements)

References 20 publications

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“…In this study, ve of the twenty unused ITNs effectively killed mosquitoes (≥80% M24) at IHI and the best performing unused ITNs had mean M24 of 99% and the worst performing unused ITNs had mean M24 of 24% measured in cone bioassay test (average from the two sites). These results agree well with other studies and WHO speci cation reports [15,33,[38][39][40][41]..Even so,, most ITNs tested at IHI gave higher KD60 than M24. It has been observed that with An.…”

Section: Discussionsupporting

confidence: 92%

“…Most previous studies using cone bioassay tests reported bioe cacy above WHO critical thresholds for unused pyrethroid ITNs [14 -25]. However, some studies reported bioe cacy below WHO critical thresholds in Benin [38], Iran [39], Madagascar [40] and PNG [41]. The reasons for this are unclear but our study corroborates the recent ndings from PNG [41].…”

Section: Discussionsupporting

confidence: 85%

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Cone Bioassays Provide Reproducible Bioefficacy Estimates with Different Anopheline Mosquitoes and Can Be Used for Quality Assurance of Pyrethroid Insecticide Treated Nets

Mbwambo

Bubun

Mbuba

et al. 2022

Preprint

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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. The cone bioassay provides a simple evaluation of ITN bioefficacy and its conditions and parameters are prescribed by the World Health Organization (WHO). This study explored utility of cone bioassays for pre-delivery QA of pyrethroid ITNs in two test facilities using different mosquito species to test the assumption that cone bioassays are consistent and reproducible across locations, mosquito strains, and laboratories. Methods Double-blinded bioassays were conducted on unused pyrethroid ITNs of 4 brands (5 nets/brand, 5 subsamples/net) that had been delivered for mass distribution in Papua New Guinea (PNG) having passed physiochemical testing of chemical content. Cone bioassays were performed on adjacent net pieces following WHO guidelines at the PNG Institute of Medical Research (PNGIMR) using pyrethroid susceptible Anopheles farauti s.s. and at Ifakara Health Institute (IHI), Tanzania using pyrethroid susceptible Anopheles gambiae s.s. Additionally, WHO tunnel tests was conducted at IHI on ITNs that did not meet cone bioefficacy thresholds. Results from IHI and PNGIMR were compared using Spearman’s Rank, Bland Altman and Cohen’s kappa. A literature review on the utility of cone bioassays for unused pyrethroid ITNs testing was also conducted. Results In cone bioassays, 13/20 nets (65%) met WHO bioefficacy criteria at IHI and 8/20 (40%) at PNGIMR. All nets met WHO bioefficacy criteria on combined cone/tunnel tests. Results from IHI and PNGIMR correlated on 60-minute knockdown (rs=0.6,p=0.002,n=20) and 24-hour mortality (rs=0.9,p<0.0001,n=20) but there was systematic bias between the results measured by Bland Altman. 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. The agreement between the results to predict ITN failure was good with kappa=0.79 (0.53-1.00) and 90% accuracy. Conclusions WHO cone is a reproducible means to measure pyrethroid ITN bioefficacy using a combination of knockdown and mortality. In the absence of an alternative tests, cone tests could be used to assess the availability of active ingredients at the surface of ITN (where mosquitoes encounter it) as part of pre-delivery QA.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 85%

Cone Bioassays Provide Reproducible Bioefficacy Estimates with Different Anopheline Mosquitoes and Can Be Used for Quality Assurance of Pyrethroid Insecticide Treated Nets

Mbwambo

Bubun

Mbuba

et al. 2022

Preprint

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show abstract

“…Most previous studies identified from the literature review using cone bioassay tests reported bioefficacy above WHO critical thresholds for unused pyrethroid ITNs [15][16][17][18][19][20][21][22][23][24][25][26]. However, a handful of studies reported bioefficacy below WHO critical thresholds in Benin [43], Iran [44], Madagascar [45], and PNG [46]. The reasons for this are unclear but our study corroborates the recent findings from PNG [46].…”

Section: Discussionsupporting

confidence: 84%

Comparison of cone bioassay estimates at two laboratories with different Anopheles mosquitoes for quality assurance of pyrethroid insecticide-treated nets

Mbwambo

Bubun

Mbuba

et al. 2022

Malar J

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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.

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“…In tests conducted in an African setting (Northern Tanzania), PermaNet ® 2.0 from 2017 were reported to fulfil all requirements 32 . However in a recent report from Iran, PermaNet ® 2.0 did not seem to fulfil bioefficacy requirements 33 . Studies also investigated the effect of developing pyrethroid resistance on PermaNet ® 2.0 bioefficacy, e.g.…”

Section: Discussionmentioning

confidence: 95%

Decreased bioefficacy of long-lasting insecticidal nets and the resurgence of malaria in Papua New Guinea

et al. 2020

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Papua New Guinea (PNG) has the highest malaria transmission outside of Africa. Longlasting insecticidal nets (LLINs) are believed to have helped to reduce average malaria prevalence in PNG from 16% in 2008 to 1% in 2014. Since 2015 malaria in PNG has resurged significantly. Here, we present observations documenting decreased bioefficacy of unused LLINs with manufacturing dates between 2013 and 2019 collected from villages and LLIN distributors in PNG. Specifically, we show that of n = 167 tested LLINs manufactured after 2013, only 17% are fulfilling the required World Health Organisation bioefficacy standards of ≥ 80% 24 h mortality or ≥ 95% 60 min knockdown in bioassays with pyrethroid susceptible Anopheles farauti mosquitoes. In contrast, all (100%, n = 25) LLINs with manufacturing dates prior to 2013 are meeting these bioefficacy standards. These results suggest that decreased bioefficacy of LLINs is contributing to the malaria resurgence in PNG and increased scrutiny of LLIN quality is warranted.

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Evaluation on the bioefficacy of PermaNet® 2.0, a long lasting net against Anopheles stephensi

Cited by 7 publications

References 20 publications

Cone Bioassays Provide Reproducible Bioefficacy Estimates with Different Anopheline Mosquitoes and Can Be Used for Quality Assurance of Pyrethroid Insecticide Treated Nets

Cone Bioassays Provide Reproducible Bioefficacy Estimates with Different Anopheline Mosquitoes and Can Be Used for Quality Assurance of Pyrethroid Insecticide Treated Nets

Comparison of cone bioassay estimates at two laboratories with different Anopheles mosquitoes for quality assurance of pyrethroid insecticide-treated nets

Decreased bioefficacy of long-lasting insecticidal nets and the resurgence of malaria in Papua New Guinea

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