Investigating insecticide resistance and knock-down resistance (kdr) mutation in Dielmo, Senegal, an area under long lasting insecticidal-treated nets universal coverage for 10 years

Thiaw, Omar Thiom; Doucouré, Souleymane; Sougoufara, Seynabou; Bouganali, Charles; Konaté, Lassana; Diagne, Nafissatou; Faye, Ousmane; Sokhna, Cheikh

doi:10.1186/s12936-018-2276-7

Cited by 30 publications

(33 citation statements)

References 51 publications

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“…This hypothesis should be investigated in the future. These results are in line with those of Thiaw et al [31] and Ahoua et al [32], who found no correlation between the kdr mutation and the phenotypic alive or dead phenotypic respectively in An. arabiensis and An.…”

Section: Discussionsupporting

confidence: 93%

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Multiple Insecticide Resistance Target Sites in Adult Field Strains of An. Gambiae s.l. From Southeast Senegal.

Diouf

Niang

Samb

et al. 2020

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Background: Malaria prevention strategies are based on the use of long-lasting insecticide-treated mosquito nets (LLINs), indoor residual spraying of insecticides (IRS) and seasonal malaria chemoprevention (SMC). The combination of these strategies with artemisinin-based combination therapy (ACTs) has led to a significant reduction in malaria cases. However, malaria remains a major public health issue in most sub-Saharan African countries. Indeed, the resistance of vectors to most WHO-approved insecticides could jeopardize vector-control strategies. This study examines insecticide resistance and associated genetic mutations among malaria vectors in southeast Senegal. Methods: The study was conducted in October and November 2014 in two sites in southeast Senegal. An. gambiae s.l. populations were sampled from Kedougou (Kedougou district) and Wassadou-Badi (Tambacounda district) and were evaluated for insecticide resistance according to WHO susceptibility tests. Specimens were 3 to 5-day-old adults raised from collected larvae. Eleven insecticides belonging to the four known classes of insecticides were assessed. Mosquito species were identified and mutations associated with insecticide resistance (ace-1, rdl (A296S or A296G), Vgsc-1014F and Vgsc-1014S) were determined. Results: A total of 3,742 An. gambiae s.l. were exposed to insecticides (2,439 from Kedougou and 1,303 from Wassadou-Badi). In both sites, mosquitoes showed high levels of resistance to all the five pyrethroids tested (mortality rates ranged from 42.8 to 81.4% in Kedougou and 52.4 to 86.4% in Wassadou-Badi) as well as to dieldrin (67.8 and 83%) and DDT (12.7 and 55%). The mosquitoes were susceptible to pirimiphos-methyl (mortality rate 100%) and malathion (mortality rates 100% and 99% in Kedougou and Wassadou-Badi respectively). An. gambiae s.l. populations from Kedougou were also resistant to bendiocarb. Of the 745 An. gambiae s.l. genotyped An. gambiae s.s. (71.6%) was the predominant species, followed by An. arabiensis (21.7%), An. coluzzii (6.3%) and hybrids (An. gambiae s.s./An. coluzzii; 0.4%). The Vgsc-1014F kdr mutation was widely distributed and is predominant in An. gambiae s.s. and An. coluzzii in comparison to An. arabiensis. Vgsc-1014S was present in An. gambiae s.l. populations in Wassadou but not in Kedougou. The ace-1 and rdl mutations were more frequent in An. gambiae s.s. compared to An. arabiensis but were not detected in all populations of An. coluzzii.Conclusion: The present study demonstrates the resistance of malaria vectors to pyrethroids and organo chlorines in southeast Senegal as well as the presence of genetic mutations associated with this resistance in An. gambiae s.l. There was no Vgsc-1014S mutation in An. gambiae s.s. population in Kedougou. These findings are key for monitoring and managing the resistance of vectors to insecticides in this region.

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Section: Discussionsupporting

confidence: 93%

“…Previous studies have reported resistance only to DDT and pyrethroids in southeastern and central Senegal where LLIN use is high, [30,31]. However, unlike previous studies conducted in Senegal, this study shows that vectors are resistant to almost all pyrethroids and bendiocarb.…”

Section: Discussioncontrasting

confidence: 82%

Multiple Insecticide Resistance Target Sites in Adult Field Strains of An. Gambiae s.l. From Southeast Senegal.

Diouf

Niang

Samb

et al. 2020

Preprint

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Section: Discussioncontrasting

confidence: 84%

“…gambiae s.l. to insecticides have revealed, often at different levels, a phenotypic resistance to DDT and to pyrethroids in most parts of Senegal, except in the north and extreme southeast [13,31,30]. The aims of this study were to update the current status of insecticide resistance among An.…”

Section: Introductionmentioning

confidence: 99%

Multiple insecticide resistance target sites in adult field strains of An. gambiae s.l. from southeast Senegal.

Diouf

Niang

Samb

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Background: Malaria prevention strategies are based on the use of long-lasting insecticide-treated mosquito nets (LLINs), indoor residual spraying of insecticides (IRS) and seasonal malaria chemoprevention (SMC). The combination of these strategies with artemisinin-based combination therapy (ACTs) has led to a significant reduction in malaria cases. However, malaria remains a major public health issue in most sub-Saharan African countries. Indeed, the resistance of vectors to most WHO-approved insecticides could jeopardize vector-control strategies. This study examines insecticide resistance and associated genetic mutations among malaria vectors in southeast Senegal. Methods: The study was conducted in October and November 2014 in two sites in southeast Senegal. An. gambiae s.l. populations were sampled from Kedougou (Kedougou district) and Wassadou-Badi (Tambacounda district) and were evaluated for insecticide resistance according to WHO susceptibility tests. Specimens were 3 to 5-day-old adults raised from collected larvae. Eleven insecticides belonging to the four known classes of insecticides were assessed. Mosquito species were identified and mutations associated with insecticide resistance (ace-1, rdl (A296S or A296G), Vgsc-1014F and Vgsc-1014S) were determined. Results: A total of 3,742 An. gambiae s.l. were exposed to insecticides (2,439 from Kedougou and 1,303 from Wassadou-Badi). In both sites, mosquitoes showed high levels of resistance to all the five pyrethroids tested (mortality rates ranged from 42.8 to 81.4% in Kedougou and 52.4 to 86.4% in Wassadou-Badi) as well as to dieldrin (67.8 and 83%) and DDT (12.7 and 55%). The mosquitoes were susceptible to pirimiphos-methyl (mortality rate 100%) and malathion (mortality rates 100% and 99% in Kedougou and Wassadou-Badi respectively). An. gambiae s.l. populations from Kedougou were also resistant to bendiocarb and fenitrothion. Of the 745 An. gambiae s.l. genotyped An. gambiae s.s. (71.6%) was the predominant species, followed by An. arabiensis (21.7%), An. coluzzii (6.3%) and hybrids (An. gambiae s.s./An. coluzzii; 0.4%). The Vgsc-1014F mutation was widely distributed and is predominant in An. gambiae s.s. and An. coluzzii in comparison to An. arabiensis. Vgsc-1014S was present in An. gambiae s.l. populations in Wassadou but not in Kedougou. The ace-1 and rdl mutations were more frequent in An. gambiae s.s. compared to An. arabiensis whereas they were detected weakly in An. coluzzii populations.Conclusions: The present study demonstrates the resistance of malaria vectors to pyrethroids and organo chlorines in southeast Senegal as well as the presence of genetic mutations associated with this resistance in An. gambiae s.l. No Vgsc-1014S mutation was detected in An. gambiae s.s. population in Kedougou. These findings are key for monitoring and managing the resistance of vectors to insecticides in this region.

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“…The adults An. arabiensis issued from a larval population carry kdr alleles despite the fact that this was not associated with resistance to pyrethroids [33], while no data regarding An. funestus is available, although its resistance to lambda-cyhalothrin has been recorded elsewhere in Senegal [34].…”

Section: Discussionmentioning

confidence: 99%

Anopheles arabiensis and Anopheles funestus biting patterns in Dielmo, an area of low level exposure to malaria vectors

Doucouré¹,

Thiaw

Wotodjo

et al. 2020

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Background In Dielmo, Senegal, the widespread use of long-lasting insecticidal nets has decreased both the incidence of malaria and the density of the Anopheles population. However, persistent low-level malaria transmission may hamper efforts to eliminate the disease. Therefore, continuous monitoring of the vector population is needed in order to improve knowledge of Anopheles biting behaviour and to readjust control interventions.Methods In 2015, Anopheles were collected every month for a whole year and each specimen was identified using morphological and molecular techniques. The biting pattern of each species was analysed according to night (7pm–7am) and morning (7am–11am) periods, the place of biting and the season. The ELISA CSP technique was used to assess the Plasmodium falciparum sporozoite rate to evaluate the entomological inoculation rate (EIR).Results Anopheles arabiensis and Anopheles funestus sensu stricto were found to be the main vectors biting humans. Overall, the biting rate was low, at 3.84bites per night (bpn) and 1.27 bites per morning (bpm), respectively (IRR =3.04, CI = [1.84-5.00], p<0.001). The EIR was 2.51 and 5.03 infectious bites per year during the night and morning, respectively. During the night, the An. arabiensis and An. funestus biting rate was 1.81 bpn and 1.71 bpn, respectively (IRR=0.95, CI= [0.46-1.92], p=0.88). During the morning, their density decreased to 0.51 bpm and 0.73 bpm for An. arabiensis and An. funestus, respectively (IRR=1.47, CI= [0.58-3.71], p=0.41). During the night and the morning, no specific trend of indoor or outdoor biting was observed in the dry and rainy season for both vectors. Conclusion This study highlighted low level Anopheles nocturnal and diurnal biting and the associated risk of malaria transmission. It showed also the influence of the season on the indoor and outdoor biting pattern, indicating that the human population could be exposed all year round to a low level of Anopheles bites. Control programmes should increase awareness of the use of bed nets throughout the year and promote the development and implementation of complimentary tools to target Anopheles biting shortly after dawn when people are still indoors.

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Investigating insecticide resistance and knock-down resistance (kdr) mutation in Dielmo, Senegal, an area under long lasting insecticidal-treated nets universal coverage for 10 years

Cited by 30 publications

References 51 publications

Multiple Insecticide Resistance Target Sites in Adult Field Strains of An. Gambiae s.l. From Southeast Senegal.

Multiple Insecticide Resistance Target Sites in Adult Field Strains of An. Gambiae s.l. From Southeast Senegal.

Multiple insecticide resistance target sites in adult field strains of An. gambiae s.l. from southeast Senegal.

Anopheles arabiensis and Anopheles funestus biting patterns in Dielmo, an area of low level exposure to malaria vectors

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