Most national malaria control programmes rely extensively on pyrethroid insecticides to control mosquito vectors of this disease. Unfortunately, the intensive use of this class of insecticides both in public health an...Most national malaria control programmes rely extensively on pyrethroid insecticides to control mosquito vectors of this disease. Unfortunately, the intensive use of this class of insecticides both in public health and agriculture has led to its reduced efficacy. The objective of this review was to assess the role of agricultural pesticides use on the development of resistance to insecticides in malaria vectors and the potential impact of this resistance on control activities. We searched library catalogues and public databases for studies that included data on resistance to the major classes of insecticides: organochlorines, carbamates, organophosphates and pyrethroids, in the malaria vectors of Anopheles genera. There is a strong geographical bias in published studies many originating from West African countries. Several studies demonstrate that resistance to pyrethroids is widespread in the major malaria vectors of the Anopheles gambiae and Anopheles funestus complexes. Assessing the impact of insecticide resistance on vector control is complicated owing to the lack of studies into the epidemiological consequences of resistance on the control of malaria and other vector borne diseases.展开更多
Background:Aedes aegypti(Diptera:Culicidae)is the main vector of the dengue virus globally.Dengue vector control is mainly based on reducing the vector population through interventions,which target potential breeding ...Background:Aedes aegypti(Diptera:Culicidae)is the main vector of the dengue virus globally.Dengue vector control is mainly based on reducing the vector population through interventions,which target potential breeding sites.However,in Tanzania,little is known about this vector’s habitat productivity and insecticide susceptibility status to support evidence-based implementation of control measures.The present study aimed at assessing the productivity and susceptibility status of A.aegypti mosquitoes to pyrethroid-based insecticides in Dar es Salaam,Tanzania.Methods:An entomological assessment was conducted between January and July 2015 in six randomly selected wards in Dar es Salaam,Tanzania.Habitat productivity was determined by the number of female adult A.aegypti mosquitoes emerged per square metre.The susceptibility status of adult A.aegypti females after exposure to 0.05%deltamethrin,0.75%permethrin and 0.05%lambda-cyhalothrin was evaluated using the standard WHO protocols.Mortality rates were recorded after 24 h exposure and the knockdown effect was recorded at the time points of 10,15,20,30,40,50 and 60 min to calculate the median knockdown times(KDT50 and KDT95).Results:The results suggest that disposed tyres had the highest productivity,while water storage tanks had the lowest productivity among the breeding habitats Of A.aegypti mosquitoes.All sites demonstrated reduced susceptibility to deltamethrin(0.05%)within 24 h post exposure,with mortalities ranging from 86.3±1.9(mean±SD)to 96.8±0.9(mean±SD).The lowest and highest susceptibilities were recorded in Mikocheni and Sinza wards,respectively.Similarly,all sites demonstrated reduced susceptibility permethrin(0.75%)ranging from 83.1±2.1%(mean±SD)to 96.2±0.9%(mean±SD),in Kipawa and Sinza,respectively.Relatively low mortality rates were observed in relation to lambda-cyhalothrin(0.05%)at all sites,ranging from 83.1±0.7(mean±SD)to 86.3±1.4(mean±SD).The median KDT_(50)for deltamethrin,permethrin and lambda-cyhalothrin were 24.9-30.3 min,24.3-34.4 min and 26.7-32.8 min,respectively.The KDT_(95)were 55.2-90.9 min for deltamethrin,54.3-94.6 min for permethrin and 64.5-69.2 min for lambda-cyhalothrin.Conclusions:The productive habitats for A.aegypti mosquitoes found in Dar es Salaam were water storage containers,discarded tins and tyres.There was a reduced susceptibility of A.aegypti to and emergence of resistance against pyrethroid-based insecticides.The documented differences in the resistance profiles of A.aegypti mosquitoes warrants regular monitoring the pattern concerning resistance against pyrethroid-based insecticides and define dengue vector control strategies.展开更多
文摘Most national malaria control programmes rely extensively on pyrethroid insecticides to control mosquito vectors of this disease. Unfortunately, the intensive use of this class of insecticides both in public health and agriculture has led to its reduced efficacy. The objective of this review was to assess the role of agricultural pesticides use on the development of resistance to insecticides in malaria vectors and the potential impact of this resistance on control activities. We searched library catalogues and public databases for studies that included data on resistance to the major classes of insecticides: organochlorines, carbamates, organophosphates and pyrethroids, in the malaria vectors of Anopheles genera. There is a strong geographical bias in published studies many originating from West African countries. Several studies demonstrate that resistance to pyrethroids is widespread in the major malaria vectors of the Anopheles gambiae and Anopheles funestus complexes. Assessing the impact of insecticide resistance on vector control is complicated owing to the lack of studies into the epidemiological consequences of resistance on the control of malaria and other vector borne diseases.
基金This study had some financial support from LM’s and VB’s families.Some support was also provided by the Institute of Traditional Medicine at Muhimbili University College of Health,and other materials were funded through the Tanzania Commission for Science and Technology(COSTECH)National Research Foundation(NRF)(grant no.TZ-RSA/JRP/RG.2013.08).
文摘Background:Aedes aegypti(Diptera:Culicidae)is the main vector of the dengue virus globally.Dengue vector control is mainly based on reducing the vector population through interventions,which target potential breeding sites.However,in Tanzania,little is known about this vector’s habitat productivity and insecticide susceptibility status to support evidence-based implementation of control measures.The present study aimed at assessing the productivity and susceptibility status of A.aegypti mosquitoes to pyrethroid-based insecticides in Dar es Salaam,Tanzania.Methods:An entomological assessment was conducted between January and July 2015 in six randomly selected wards in Dar es Salaam,Tanzania.Habitat productivity was determined by the number of female adult A.aegypti mosquitoes emerged per square metre.The susceptibility status of adult A.aegypti females after exposure to 0.05%deltamethrin,0.75%permethrin and 0.05%lambda-cyhalothrin was evaluated using the standard WHO protocols.Mortality rates were recorded after 24 h exposure and the knockdown effect was recorded at the time points of 10,15,20,30,40,50 and 60 min to calculate the median knockdown times(KDT50 and KDT95).Results:The results suggest that disposed tyres had the highest productivity,while water storage tanks had the lowest productivity among the breeding habitats Of A.aegypti mosquitoes.All sites demonstrated reduced susceptibility to deltamethrin(0.05%)within 24 h post exposure,with mortalities ranging from 86.3±1.9(mean±SD)to 96.8±0.9(mean±SD).The lowest and highest susceptibilities were recorded in Mikocheni and Sinza wards,respectively.Similarly,all sites demonstrated reduced susceptibility permethrin(0.75%)ranging from 83.1±2.1%(mean±SD)to 96.2±0.9%(mean±SD),in Kipawa and Sinza,respectively.Relatively low mortality rates were observed in relation to lambda-cyhalothrin(0.05%)at all sites,ranging from 83.1±0.7(mean±SD)to 86.3±1.4(mean±SD).The median KDT_(50)for deltamethrin,permethrin and lambda-cyhalothrin were 24.9-30.3 min,24.3-34.4 min and 26.7-32.8 min,respectively.The KDT_(95)were 55.2-90.9 min for deltamethrin,54.3-94.6 min for permethrin and 64.5-69.2 min for lambda-cyhalothrin.Conclusions:The productive habitats for A.aegypti mosquitoes found in Dar es Salaam were water storage containers,discarded tins and tyres.There was a reduced susceptibility of A.aegypti to and emergence of resistance against pyrethroid-based insecticides.The documented differences in the resistance profiles of A.aegypti mosquitoes warrants regular monitoring the pattern concerning resistance against pyrethroid-based insecticides and define dengue vector control strategies.
