Anopheles gambiae populations from Burkina Faso show minimal delayed mortality after exposure to insecticide-treated nets
Abstract Background The efficacy of long-lasting insecticidal nets (LLINs) in preventing malaria in Africa is threatened by insecticide resistance. Bioassays assessing 24-hour mortality post-LLIN exposure have established that resistance to the concentration of pyrethroids used in LLINs is widesprea...
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| Format: | Article |
| Language: | English |
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BMC
2020-01-01
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| Series: | Parasites & Vectors |
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| Online Access: | https://doi.org/10.1186/s13071-019-3872-2 |
| _version_ | 1818645261014007808 |
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| author | Angela Hughes Natalie Lissenden Mafalda Viana Kobié Hyacinthe Toé Hilary Ranson |
| author_facet | Angela Hughes Natalie Lissenden Mafalda Viana Kobié Hyacinthe Toé Hilary Ranson |
| author_sort | Angela Hughes |
| collection | DOAJ |
| description | Abstract Background The efficacy of long-lasting insecticidal nets (LLINs) in preventing malaria in Africa is threatened by insecticide resistance. Bioassays assessing 24-hour mortality post-LLIN exposure have established that resistance to the concentration of pyrethroids used in LLINs is widespread. However, although mosquitoes may no longer be rapidly killed by LLIN exposure, a delayed mortality effect has been shown to reduce the transmission potential of mosquitoes exposed to nets. This has been postulated to partially explain the continued efficacy of LLINs against pyrethroid-resistant populations. Burkina Faso is one of a number of countries with very high malaria burdens and pyrethroid-resistant vectors, where progress in controlling this disease has stagnated. We measured the impact of LLIN exposure on mosquito longevity in an area of the country with intense pyrethroid resistance to establish whether pyrethroid exposure was still shortening mosquito lifespan in this setting. Methods We quantified the immediate and delayed mortality effects of LLIN exposure using standard laboratory WHO cone tests, tube bioassays and experimental hut trials on Anopheles gambiae populations originating from the Cascades region of Burkina Faso using survival analysis and a Bayesian state-space model. Results Following single and multiple exposures to a PermaNet 2.0 LLIN only one of the four mosquito populations tested showed evidence of delayed mortality. No delayed mortality was seen in experimental hut studies using LLINs. A delayed mortality effect was only observed in WHO tube bioassays when deltamethrin concentration was increased above the standard diagnostic dose. Conclusions As mosquito pyrethroid-resistance increases in intensity, delayed effects from LLIN exposure are substantially reduced or absent. Given the rapid increase in resistance occurring in malaria vectors across Africa it is important to determine whether the failure of LLINs to shorten mosquito lifespan is now a widespread phenomenon as this will have important implications for the future of this pivotal malaria control tool. |
| first_indexed | 2024-12-17T00:27:56Z |
| format | Article |
| id | doaj.art-2c664e56ba8d4f8791a1bddbaa463912 |
| institution | Directory Open Access Journal |
| issn | 1756-3305 |
| language | English |
| last_indexed | 2024-12-17T00:27:56Z |
| publishDate | 2020-01-01 |
| publisher | BMC |
| record_format | Article |
| series | Parasites & Vectors |
| spelling | doaj.art-2c664e56ba8d4f8791a1bddbaa4639122022-12-21T22:10:25ZengBMCParasites & Vectors1756-33052020-01-0113111110.1186/s13071-019-3872-2Anopheles gambiae populations from Burkina Faso show minimal delayed mortality after exposure to insecticide-treated netsAngela Hughes0Natalie Lissenden1Mafalda Viana2Kobié Hyacinthe Toé3Hilary Ranson4Department of Vector Biology, Liverpool School of Tropical MedicineDepartment of Vector Biology, Liverpool School of Tropical MedicineInstitute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of GlasgowCentre National de Recherche et de Formation sur le PaludismeDepartment of Vector Biology, Liverpool School of Tropical MedicineAbstract Background The efficacy of long-lasting insecticidal nets (LLINs) in preventing malaria in Africa is threatened by insecticide resistance. Bioassays assessing 24-hour mortality post-LLIN exposure have established that resistance to the concentration of pyrethroids used in LLINs is widespread. However, although mosquitoes may no longer be rapidly killed by LLIN exposure, a delayed mortality effect has been shown to reduce the transmission potential of mosquitoes exposed to nets. This has been postulated to partially explain the continued efficacy of LLINs against pyrethroid-resistant populations. Burkina Faso is one of a number of countries with very high malaria burdens and pyrethroid-resistant vectors, where progress in controlling this disease has stagnated. We measured the impact of LLIN exposure on mosquito longevity in an area of the country with intense pyrethroid resistance to establish whether pyrethroid exposure was still shortening mosquito lifespan in this setting. Methods We quantified the immediate and delayed mortality effects of LLIN exposure using standard laboratory WHO cone tests, tube bioassays and experimental hut trials on Anopheles gambiae populations originating from the Cascades region of Burkina Faso using survival analysis and a Bayesian state-space model. Results Following single and multiple exposures to a PermaNet 2.0 LLIN only one of the four mosquito populations tested showed evidence of delayed mortality. No delayed mortality was seen in experimental hut studies using LLINs. A delayed mortality effect was only observed in WHO tube bioassays when deltamethrin concentration was increased above the standard diagnostic dose. Conclusions As mosquito pyrethroid-resistance increases in intensity, delayed effects from LLIN exposure are substantially reduced or absent. Given the rapid increase in resistance occurring in malaria vectors across Africa it is important to determine whether the failure of LLINs to shorten mosquito lifespan is now a widespread phenomenon as this will have important implications for the future of this pivotal malaria control tool.https://doi.org/10.1186/s13071-019-3872-2MosquitoAnophelesInsecticide resistanceDelayed mortalityLongevitySub-lethal effects |
| spellingShingle | Angela Hughes Natalie Lissenden Mafalda Viana Kobié Hyacinthe Toé Hilary Ranson Anopheles gambiae populations from Burkina Faso show minimal delayed mortality after exposure to insecticide-treated nets Parasites & Vectors Mosquito Anopheles Insecticide resistance Delayed mortality Longevity Sub-lethal effects |
| title | Anopheles gambiae populations from Burkina Faso show minimal delayed mortality after exposure to insecticide-treated nets |
| title_full | Anopheles gambiae populations from Burkina Faso show minimal delayed mortality after exposure to insecticide-treated nets |
| title_fullStr | Anopheles gambiae populations from Burkina Faso show minimal delayed mortality after exposure to insecticide-treated nets |
| title_full_unstemmed | Anopheles gambiae populations from Burkina Faso show minimal delayed mortality after exposure to insecticide-treated nets |
| title_short | Anopheles gambiae populations from Burkina Faso show minimal delayed mortality after exposure to insecticide-treated nets |
| title_sort | anopheles gambiae populations from burkina faso show minimal delayed mortality after exposure to insecticide treated nets |
| topic | Mosquito Anopheles Insecticide resistance Delayed mortality Longevity Sub-lethal effects |
| url | https://doi.org/10.1186/s13071-019-3872-2 |
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