Objective:To evaluate 11 Cuban native Bacillus(B.)thuringiensis isolates in order to select one with the best larvicidal activity against Aedes(Ae.)aegypti and low cytotoxicity.Methods:The cry and cyt genes of the iso...Objective:To evaluate 11 Cuban native Bacillus(B.)thuringiensis isolates in order to select one with the best larvicidal activity against Aedes(Ae.)aegypti and low cytotoxicity.Methods:The cry and cyt genes of the isolates(A21,A51,L95,L910,M29,R84,R85,R87,R89,U81 and X48)were amplified by PCR.The influence of organic matter and NaCl on the larvicidal activity was tested by bioassays.Cytotoxicity was assayed on peritoneal macrophages of BALB/c mice.Results:The cyt1(Aa,Ab,Ba),cyt2,cry4aA,cry4Ba,cry11(Aa,Ba,Bb)and cry10 genes were identified in all native Cuban isolates.The larvicidal activity(LC_(90))of seven isolates was affected by the presence of organic matter in the water,while A21,A51,L910,R84,U81 and X48 had better LC_(50),LC_(90),LC_(95) than the 266/29-Ⅶ-98 control strain.The LC_(50) of two isolates was affected by the presence of NaCl and A21,A51,R85 isolate had better larvicidal activity than the 266/29-Ⅶ-98 control strain.In terms of toxicity against macrophages,the extracts of nine isolates were less cytotoxic than the control strains.Conclusions:Native isolate A21 had the main virulence factors against Ae.aegypti larvae,displayed a good larvicidal activity in presence of different factors related with Ae.aegypti breeding sites,and had low citotoxicity against macrophages.These results can contribute to the improvement of existing biological control strategies and the development of new biolarvicides.展开更多
Over the past decade, a dramatic rise in bedbug resurgence has become one of the top potential public health hazards. This study was conducted to determine prevalence, knowledge and self-reported containment practices...Over the past decade, a dramatic rise in bedbug resurgence has become one of the top potential public health hazards. This study was conducted to determine prevalence, knowledge and self-reported containment practices about bedbugs in the resource-limited setting of Ethiopia. A community based, cross-sectional survey was conducted between January and May 2014. Selected 260 respondents were interviewed by the administration of a pre-tested questionnaire on knowledge and practices about bedbug infestation in the resource-limited setting of Ethiopia. Overall, 91.6% (238/260) of the residents had ample awareness on bedbug infestation. The majority of them (97.2%) extremely bothered about infestations because of bad odors (83.8%), insomnia (79.8%), biting (66.9%), and skin rashes (56.9%). A high prevalence of infestation (72.7%) was observed. Bedrooms and main hall/salon were identified as potential high-risk areas. Chi-square exhibited a strong association between sanitary status and housing conditions (χ2 = 40.91;df = 4;P = 0.0001). Besides, there was a strong association between respondents’ monthly income (χ2 = 42.1;df = 6;P = 0.0001) and educational status (χ2 = 26.01;df = 5;P = 0.0001) with the presence or absence of bedbug infestation. Though the majority of respondents had adequate knowledge, they suffer with deprived practices attributable to deficient resources as well as negligence/ignorance. This study emphasizes the following key interventions: 1) community-based awareness campaigns, 2) implementation of sustainable preventive/containment strategies, 3) educational interventions to ensure translation of knowledge into practices, and 4) the implementation of appropriate poverty alleviation programs to enhance the local-residents living-standard in the future.展开更多
The efficacy of insecticide-treated nets (ITNs) is increasingly compromised by the prevalence of malaria vectors resistant to pyrethroids. In response to this issue, a new generation of ITNs has been developed that in...The efficacy of insecticide-treated nets (ITNs) is increasingly compromised by the prevalence of malaria vectors resistant to pyrethroids. In response to this issue, a new generation of ITNs has been developed that incorporate synergistic components, such as piperonyl butoxide (PBO). The purpose of this study is to provide entomological evidence for the efficacy of a PBO-based ITN brand at the village level, serving as a basis for decision-making before large-scale net deployment. During the high malaria transmission period, ITNs were distributed in each group and vector sampling was conducted biweekly in selected households. Bionomic data were collected to assess the resistance of wild An. gambiae populations to various chemical insecticides. There was a significant disparity in total An. gambiae sl. collected between the ITN arms, the intervention arm (ITN arms), and the control arm (P = 0.003). An. coluzzi was identified as the predominant species in the study area, as confirmed by PCR analysis. Analysis of the blood-feeding inhibition rate revealed that 100% permethrin + PBO ITN exhibited significantly greater inhibition than 66.81% permethrin only ITN. According to the log-time probit regression analysis, permethrin exhibited a knockdown time of 256 min without synergists, while it decreased to 139 min (P = 0.001) when pre-exposed to PBO. The evidence from this trial supports the use of PBO ITNs over standard ITNs for pyrethroids to combat pyrethroid resistance and improve protection against malaria for both individuals and communities, particularly in areas with high pyrethroid resistance.展开更多
文摘Objective:To evaluate 11 Cuban native Bacillus(B.)thuringiensis isolates in order to select one with the best larvicidal activity against Aedes(Ae.)aegypti and low cytotoxicity.Methods:The cry and cyt genes of the isolates(A21,A51,L95,L910,M29,R84,R85,R87,R89,U81 and X48)were amplified by PCR.The influence of organic matter and NaCl on the larvicidal activity was tested by bioassays.Cytotoxicity was assayed on peritoneal macrophages of BALB/c mice.Results:The cyt1(Aa,Ab,Ba),cyt2,cry4aA,cry4Ba,cry11(Aa,Ba,Bb)and cry10 genes were identified in all native Cuban isolates.The larvicidal activity(LC_(90))of seven isolates was affected by the presence of organic matter in the water,while A21,A51,L910,R84,U81 and X48 had better LC_(50),LC_(90),LC_(95) than the 266/29-Ⅶ-98 control strain.The LC_(50) of two isolates was affected by the presence of NaCl and A21,A51,R85 isolate had better larvicidal activity than the 266/29-Ⅶ-98 control strain.In terms of toxicity against macrophages,the extracts of nine isolates were less cytotoxic than the control strains.Conclusions:Native isolate A21 had the main virulence factors against Ae.aegypti larvae,displayed a good larvicidal activity in presence of different factors related with Ae.aegypti breeding sites,and had low citotoxicity against macrophages.These results can contribute to the improvement of existing biological control strategies and the development of new biolarvicides.
文摘Over the past decade, a dramatic rise in bedbug resurgence has become one of the top potential public health hazards. This study was conducted to determine prevalence, knowledge and self-reported containment practices about bedbugs in the resource-limited setting of Ethiopia. A community based, cross-sectional survey was conducted between January and May 2014. Selected 260 respondents were interviewed by the administration of a pre-tested questionnaire on knowledge and practices about bedbug infestation in the resource-limited setting of Ethiopia. Overall, 91.6% (238/260) of the residents had ample awareness on bedbug infestation. The majority of them (97.2%) extremely bothered about infestations because of bad odors (83.8%), insomnia (79.8%), biting (66.9%), and skin rashes (56.9%). A high prevalence of infestation (72.7%) was observed. Bedrooms and main hall/salon were identified as potential high-risk areas. Chi-square exhibited a strong association between sanitary status and housing conditions (χ2 = 40.91;df = 4;P = 0.0001). Besides, there was a strong association between respondents’ monthly income (χ2 = 42.1;df = 6;P = 0.0001) and educational status (χ2 = 26.01;df = 5;P = 0.0001) with the presence or absence of bedbug infestation. Though the majority of respondents had adequate knowledge, they suffer with deprived practices attributable to deficient resources as well as negligence/ignorance. This study emphasizes the following key interventions: 1) community-based awareness campaigns, 2) implementation of sustainable preventive/containment strategies, 3) educational interventions to ensure translation of knowledge into practices, and 4) the implementation of appropriate poverty alleviation programs to enhance the local-residents living-standard in the future.
文摘The efficacy of insecticide-treated nets (ITNs) is increasingly compromised by the prevalence of malaria vectors resistant to pyrethroids. In response to this issue, a new generation of ITNs has been developed that incorporate synergistic components, such as piperonyl butoxide (PBO). The purpose of this study is to provide entomological evidence for the efficacy of a PBO-based ITN brand at the village level, serving as a basis for decision-making before large-scale net deployment. During the high malaria transmission period, ITNs were distributed in each group and vector sampling was conducted biweekly in selected households. Bionomic data were collected to assess the resistance of wild An. gambiae populations to various chemical insecticides. There was a significant disparity in total An. gambiae sl. collected between the ITN arms, the intervention arm (ITN arms), and the control arm (P = 0.003). An. coluzzi was identified as the predominant species in the study area, as confirmed by PCR analysis. Analysis of the blood-feeding inhibition rate revealed that 100% permethrin + PBO ITN exhibited significantly greater inhibition than 66.81% permethrin only ITN. According to the log-time probit regression analysis, permethrin exhibited a knockdown time of 256 min without synergists, while it decreased to 139 min (P = 0.001) when pre-exposed to PBO. The evidence from this trial supports the use of PBO ITNs over standard ITNs for pyrethroids to combat pyrethroid resistance and improve protection against malaria for both individuals and communities, particularly in areas with high pyrethroid resistance.
