Long-lasting insecticidal nets no longer effectively kill the highly resistant Anopheles funestus of southern Mozambique

Katey D. Glunt, Ana Paula Abílio, Quique Bassat, Helder Bulo, Allison E. Gilbert, Silvie Huijben, Maria Nélia Manaca, Eusebio Macete, Pedro Alonso, Krijn Paaijmans

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Background: Chemical insecticides are crucial to malaria control and elimination programmes. The frontline vector control interventions depend mainly on pyrethroids; all long-lasting insecticidal nets (LLINs) and more than 80% of indoor residual spraying (IRS) campaigns use chemicals from this class. This extensive use of pyrethroids imposes a strong selection pressure for resistance in mosquito populations, and so continuous resistance monitoring and evaluation are important. As pyrethroids have also been used for many years in the Manhiça District, an area in southern Mozambique with perennial malaria transmission, an assessment of their efficacy against the local malaria vectors was conducted. Methods: Female offspring of wild-caught Anopheles funestus s.s. females were exposed to deltamethrin, lambda-cyhalothrin and permethrin using the World Health Organization (WHO) insecticide-resistance monitoring protocols. The 3-min WHO cone bioassay was used to evaluate the effectiveness of the bed nets distributed or available for purchase in the area (Olyset, permethrin LLIN; PermaNet 2.0, deltamethrin LLIN) against An. funestus. Mosquitoes were also exposed to PermaNet 2.0 for up to 8 h in time-exposure assays. Results: Resistance to pyrethroids in An. funestus s.s. was extremely high, much higher than reported in 2002 and 2009. No exposure killed more than 25.8% of the mosquitoes tested (average mortality, deltamethrin: 6.4%; lambda-cyhalothrin: 5.1%; permethrin: 19.1%). There was no significant difference in the mortality generated by 3-min exposure to any net (Olyset: 9.3% mortality, PermaNet 2.0: 6.0%, untreated: 2.0%; p = 0.2). Six hours of exposure were required to kill 50% of the An. funestus s.s. on PermaNet 2.0. Conclusions: Anopheles funestus s.s. in Manhiça is extremely resistant to pyrethroids, and this area is clearly a pyrethroid-resistance hotspot. This could severely undermine vector control in this district if no appropriate countermeasures are undertaken. The National Malaria Control Programme (NMCP) of Mozambique is currently improving its resistance monitoring programme, to design and scale up new management strategies. These actions are urgently needed, as the goal of the NMCP and its partners is to reach elimination in southern Mozambique by 2020.

Original languageEnglish (US)
Article number298
JournalMalaria Journal
Volume14
Issue number1
DOIs
StatePublished - Aug 5 2015
Externally publishedYes

Fingerprint

Mozambique
Pyrethrins
Anopheles
Malaria
Permethrin
Culicidae
Mortality
Insecticide Resistance
Insecticides
Biological Assay
Pressure
Population
decamethrin

Keywords

  • An. arabiensis
  • Anopheles funestus
  • Bioassays
  • Insecticide resistance
  • LLINs
  • Malaria vectors
  • Mosquito control
  • Pyrethroids

ASJC Scopus subject areas

  • Parasitology
  • Infectious Diseases

Cite this

Long-lasting insecticidal nets no longer effectively kill the highly resistant Anopheles funestus of southern Mozambique. / Glunt, Katey D.; Abílio, Ana Paula; Bassat, Quique; Bulo, Helder; Gilbert, Allison E.; Huijben, Silvie; Manaca, Maria Nélia; Macete, Eusebio; Alonso, Pedro; Paaijmans, Krijn.

In: Malaria Journal, Vol. 14, No. 1, 298, 05.08.2015.

Research output: Contribution to journalArticle

Glunt, Katey D. ; Abílio, Ana Paula ; Bassat, Quique ; Bulo, Helder ; Gilbert, Allison E. ; Huijben, Silvie ; Manaca, Maria Nélia ; Macete, Eusebio ; Alonso, Pedro ; Paaijmans, Krijn. / Long-lasting insecticidal nets no longer effectively kill the highly resistant Anopheles funestus of southern Mozambique. In: Malaria Journal. 2015 ; Vol. 14, No. 1.
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title = "Long-lasting insecticidal nets no longer effectively kill the highly resistant Anopheles funestus of southern Mozambique",
abstract = "Background: Chemical insecticides are crucial to malaria control and elimination programmes. The frontline vector control interventions depend mainly on pyrethroids; all long-lasting insecticidal nets (LLINs) and more than 80{\%} of indoor residual spraying (IRS) campaigns use chemicals from this class. This extensive use of pyrethroids imposes a strong selection pressure for resistance in mosquito populations, and so continuous resistance monitoring and evaluation are important. As pyrethroids have also been used for many years in the Manhi{\cc}a District, an area in southern Mozambique with perennial malaria transmission, an assessment of their efficacy against the local malaria vectors was conducted. Methods: Female offspring of wild-caught Anopheles funestus s.s. females were exposed to deltamethrin, lambda-cyhalothrin and permethrin using the World Health Organization (WHO) insecticide-resistance monitoring protocols. The 3-min WHO cone bioassay was used to evaluate the effectiveness of the bed nets distributed or available for purchase in the area (Olyset, permethrin LLIN; PermaNet 2.0, deltamethrin LLIN) against An. funestus. Mosquitoes were also exposed to PermaNet 2.0 for up to 8 h in time-exposure assays. Results: Resistance to pyrethroids in An. funestus s.s. was extremely high, much higher than reported in 2002 and 2009. No exposure killed more than 25.8{\%} of the mosquitoes tested (average mortality, deltamethrin: 6.4{\%}; lambda-cyhalothrin: 5.1{\%}; permethrin: 19.1{\%}). There was no significant difference in the mortality generated by 3-min exposure to any net (Olyset: 9.3{\%} mortality, PermaNet 2.0: 6.0{\%}, untreated: 2.0{\%}; p = 0.2). Six hours of exposure were required to kill 50{\%} of the An. funestus s.s. on PermaNet 2.0. Conclusions: Anopheles funestus s.s. in Manhi{\cc}a is extremely resistant to pyrethroids, and this area is clearly a pyrethroid-resistance hotspot. This could severely undermine vector control in this district if no appropriate countermeasures are undertaken. The National Malaria Control Programme (NMCP) of Mozambique is currently improving its resistance monitoring programme, to design and scale up new management strategies. These actions are urgently needed, as the goal of the NMCP and its partners is to reach elimination in southern Mozambique by 2020.",
keywords = "An. arabiensis, Anopheles funestus, Bioassays, Insecticide resistance, LLINs, Malaria vectors, Mosquito control, Pyrethroids",
author = "Glunt, {Katey D.} and Ab{\'i}lio, {Ana Paula} and Quique Bassat and Helder Bulo and Gilbert, {Allison E.} and Silvie Huijben and Manaca, {Maria N{\'e}lia} and Eusebio Macete and Pedro Alonso and Krijn Paaijmans",
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T1 - Long-lasting insecticidal nets no longer effectively kill the highly resistant Anopheles funestus of southern Mozambique

AU - Glunt, Katey D.

AU - Abílio, Ana Paula

AU - Bassat, Quique

AU - Bulo, Helder

AU - Gilbert, Allison E.

AU - Huijben, Silvie

AU - Manaca, Maria Nélia

AU - Macete, Eusebio

AU - Alonso, Pedro

AU - Paaijmans, Krijn

PY - 2015/8/5

Y1 - 2015/8/5

N2 - Background: Chemical insecticides are crucial to malaria control and elimination programmes. The frontline vector control interventions depend mainly on pyrethroids; all long-lasting insecticidal nets (LLINs) and more than 80% of indoor residual spraying (IRS) campaigns use chemicals from this class. This extensive use of pyrethroids imposes a strong selection pressure for resistance in mosquito populations, and so continuous resistance monitoring and evaluation are important. As pyrethroids have also been used for many years in the Manhiça District, an area in southern Mozambique with perennial malaria transmission, an assessment of their efficacy against the local malaria vectors was conducted. Methods: Female offspring of wild-caught Anopheles funestus s.s. females were exposed to deltamethrin, lambda-cyhalothrin and permethrin using the World Health Organization (WHO) insecticide-resistance monitoring protocols. The 3-min WHO cone bioassay was used to evaluate the effectiveness of the bed nets distributed or available for purchase in the area (Olyset, permethrin LLIN; PermaNet 2.0, deltamethrin LLIN) against An. funestus. Mosquitoes were also exposed to PermaNet 2.0 for up to 8 h in time-exposure assays. Results: Resistance to pyrethroids in An. funestus s.s. was extremely high, much higher than reported in 2002 and 2009. No exposure killed more than 25.8% of the mosquitoes tested (average mortality, deltamethrin: 6.4%; lambda-cyhalothrin: 5.1%; permethrin: 19.1%). There was no significant difference in the mortality generated by 3-min exposure to any net (Olyset: 9.3% mortality, PermaNet 2.0: 6.0%, untreated: 2.0%; p = 0.2). Six hours of exposure were required to kill 50% of the An. funestus s.s. on PermaNet 2.0. Conclusions: Anopheles funestus s.s. in Manhiça is extremely resistant to pyrethroids, and this area is clearly a pyrethroid-resistance hotspot. This could severely undermine vector control in this district if no appropriate countermeasures are undertaken. The National Malaria Control Programme (NMCP) of Mozambique is currently improving its resistance monitoring programme, to design and scale up new management strategies. These actions are urgently needed, as the goal of the NMCP and its partners is to reach elimination in southern Mozambique by 2020.

AB - Background: Chemical insecticides are crucial to malaria control and elimination programmes. The frontline vector control interventions depend mainly on pyrethroids; all long-lasting insecticidal nets (LLINs) and more than 80% of indoor residual spraying (IRS) campaigns use chemicals from this class. This extensive use of pyrethroids imposes a strong selection pressure for resistance in mosquito populations, and so continuous resistance monitoring and evaluation are important. As pyrethroids have also been used for many years in the Manhiça District, an area in southern Mozambique with perennial malaria transmission, an assessment of their efficacy against the local malaria vectors was conducted. Methods: Female offspring of wild-caught Anopheles funestus s.s. females were exposed to deltamethrin, lambda-cyhalothrin and permethrin using the World Health Organization (WHO) insecticide-resistance monitoring protocols. The 3-min WHO cone bioassay was used to evaluate the effectiveness of the bed nets distributed or available for purchase in the area (Olyset, permethrin LLIN; PermaNet 2.0, deltamethrin LLIN) against An. funestus. Mosquitoes were also exposed to PermaNet 2.0 for up to 8 h in time-exposure assays. Results: Resistance to pyrethroids in An. funestus s.s. was extremely high, much higher than reported in 2002 and 2009. No exposure killed more than 25.8% of the mosquitoes tested (average mortality, deltamethrin: 6.4%; lambda-cyhalothrin: 5.1%; permethrin: 19.1%). There was no significant difference in the mortality generated by 3-min exposure to any net (Olyset: 9.3% mortality, PermaNet 2.0: 6.0%, untreated: 2.0%; p = 0.2). Six hours of exposure were required to kill 50% of the An. funestus s.s. on PermaNet 2.0. Conclusions: Anopheles funestus s.s. in Manhiça is extremely resistant to pyrethroids, and this area is clearly a pyrethroid-resistance hotspot. This could severely undermine vector control in this district if no appropriate countermeasures are undertaken. The National Malaria Control Programme (NMCP) of Mozambique is currently improving its resistance monitoring programme, to design and scale up new management strategies. These actions are urgently needed, as the goal of the NMCP and its partners is to reach elimination in southern Mozambique by 2020.

KW - An. arabiensis

KW - Anopheles funestus

KW - Bioassays

KW - Insecticide resistance

KW - LLINs

KW - Malaria vectors

KW - Mosquito control

KW - Pyrethroids

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