scholarly journals Temporally consistent predominance and distribution of secondary malaria vectors in the Anopheles community of the upper Zambezi floodplain

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Dónall Eoin Cross ◽  
Amy J. E. Healey ◽  
Niall J. McKeown ◽  
Christopher James Thomas ◽  
Nicolae Adrian Macarie ◽  
...  
Keyword(s):  
Vector Control ◽  
Community Dynamics ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Temporal Consistency ◽  
Wet Season ◽  
Spatial And Temporal Scales ◽  
Ecological Zones ◽  
Residual Malaria Transmission ◽  
Anopheline Larvae

AbstractRegional optimisation of malaria vector control approaches requires detailed understanding both of the species composition of Anopheles mosquito communities, and how they vary over spatial and temporal scales. Knowledge of vector community dynamics is particularly important in settings where ecohydrological conditions fluctuate seasonally and inter-annually, such as the Barotse floodplain of the upper Zambezi river. DNA barcoding of anopheline larvae sampled in the 2019 wet season revealed the predominance of secondary vector species, with An. coustani comprising > 80% of sampled larvae and distributed ubiquitously across all ecological zones. Extensive larval sampling, plus a smaller survey of adult mosquitoes, identified geographic clusters of primary vectors, but represented only 2% of anopheline larvae. Comparisons with larval surveys in 2017/2018 and a contemporaneous independent 5-year dataset from adult trapping corroborated this paucity of primary vectors across years, and the consistent numerical dominance of An. coustani and other secondary vectors in both dry and wet seasons, despite substantial inter-annual variation in hydrological conditions. This marked temporal consistency of spatial distribution and anopheline community composition presents an opportunity to target predominant secondary vectors outdoors. Larval source management should be considered, alongside prevalent indoor-based approaches, amongst a diversification of vector control approaches to more effectively combat residual malaria transmission.

scholarly journals Resting behaviour of malaria vectors in highland and lowland sites of western Kenya: Implication on malaria vector control measures

PLoS ONE ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. e0224718 ◽  
Author(s):  
Maxwell G. Machani ◽  
Eric Ochomo ◽  
Fred Amimo ◽  
Jackline Kosgei ◽  
Stephen Munga ◽  
...  
Keyword(s):  
Vector Control ◽  
Malaria Vector ◽  
Control Measures ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Western Kenya ◽  
Resting Behaviour

scholarly journals Quantifying and characterizing hourly human exposure to malaria vectors bites in rural southwest Burkina Faso

2019 ◽  
Author(s):  
D.D Soma ◽  
B Zogo ◽  
P Taconet ◽  
A Somé ◽  
S Coulibaly ◽  
...  
Keyword(s):  
Burkina Faso ◽  
Vector Control ◽  
Rural Area ◽  
Malaria Vector ◽  
Human Exposure ◽  
Protective Efficacy ◽  
Indoor Residual Spraying ◽  
World Health ◽  
Malaria Vectors ◽  
Malaria Vector Control

AbstractBackgroundTo sustain the efficacy of malaria vector control, the World Health Organization (WHO) recommends the combination of effective tools. Before designing and implementing additional strategies in any setting, it is critical to monitor or predict when and where transmission occurs. However, to date, very few studies have quantified the behavioural interactions between humans and Anopheles vectors. Here, we characterized residual transmission in a rural area of Burkina Faso where long lasting insecticidal nets (LLIN) are widely used.MethodsWe analysed data on both human and malaria vectors behaviours from 27 villages to measure hourly human exposure to vector bites in dry and rainy seasons using mathematical models. We estimated the protective efficacy of LLINs and characterised where (indoors vs. outdoors) and when both LLIN users and non-users were exposed to vector bites.ResultsThe percentage of the population who declared sleeping under a LLIN the previous night was very high regardless of the season, with an average LLIN use ranging from 92.43% to 99.89%. The use of LLIN provided > 80% protection against exposure to vector bites. The proportion of exposure for LLIN users was 29-57% after 05:00 and 0.05-12 % before 20:00. More than 80% of exposure occurred indoors for LLIN users and the estimate reached 90% for children under five years old in the dry cold season.ConclusionsThis study supports the current use of LLIN as a primary malaria vector control tool. It also emphasises the need to complement LLIN with indoor-implemented measures such as indoor residual spraying (IRS) and/or house improvement to effectively combat malaria in the rural area of Diébougou. Furthermore, malaria elimination programmes would also require strategies that target outdoor biting vectors to be successful in the area.

scholarly journals Efficacy of broflanilide (VECTRON™ T500), a new meta-diamide insecticide, for indoor residual spraying against pyrethroid-resistant malaria vectors

2020 ◽  
Author(s):  
Corine Ngufor ◽  
Renaud Govoetchan ◽  
Augustin Fongnikin ◽  
Estelle Vigninou ◽  
Thomas Syme ◽  
...  
Keyword(s):  
Vector Control ◽  
Malaria Vector ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Cross Resistance ◽  
Malaria Vector Control ◽  
Application Rates ◽  
Wettable Powder ◽  
Cone Bioassay ◽  
Pirimiphos Methyl

AbstractThe rotational use of insecticides with different modes of action for indoor residual spraying (IRS) is recommended for improving malaria vector control and managing insecticide resistance. A more diversified portfolio of IRS insecticides is required; insecticides with new chemistries which can provide improved and prolonged control of insecticide-resistant vector populations are urgently needed. Broflanilide is a newly discovered insecticide being considered for malaria vector control. We investigated the efficacy of a wettable powder (WP) formulation of broflanilide (VECTRON™ T500) for IRS on mud and cement wall substrates in WHO laboratory and experimental hut studies against pyrethroid-resistant malaria vectors in Benin, in comparison with pirimiphos-methyl CS (Actellic® 300CS). There was no evidence of cross-resistance to pyrethroids and broflanilide in CDC bottle bioassays. In laboratory cone bioassays, mortality of susceptible and pyrethroid-resistant A. gambiae s.l. with broflanilide WP treated substrates was >80% for 6-14 months. At application rates of 100mg/m2 and 150 mg/m2, mortality of wild pyrethroid-resistant A. gambiae s.l. entering treated experimental huts in Covè, Benin was 57%-66% with broflanilide WP and did not differ significantly from pirimiphos-methyl CS (57-66% vs. 56%, P>0.05). Mosquito mortality did not differ between the two application rates and local wall substrate-types tested (P>0.05). Throughout the 6-month hut trial, monthly wall cone bioassay mortality on broflanilide WP treated hut walls remained >80% for both susceptible and resistant strains of A. gambiae s.l.. Broflanilide shows potential to significantly improve the control of malaria transmitted by pyrethroid-resistant mosquito vectors and would thus be a crucial addition to the current portfolio of IRS insecticides.One Sentence SummaryVECTRON™ T500, a new wettable powder formulation of broflanilide developed for indoor residual spraying, showed high and prolonged activity against wild pyrethroid-resistant malaria vectors, on local wall substrates, in laboratory bioassays and experimental household settings in Benin.

scholarly journals Monitoring of Insecticide Resistance in Anopheles culicifacies in Twelve Districts of Madhya Pradesh, Central India (2017–2019)

2022 ◽  
Vol 2022 ◽  
pp. 1-8
Author(s):  
Ashok K. Mishra ◽  
Praveen K Bharti ◽  
Gyan Chand ◽  
Aparup Das ◽  
Himanshu Jayswar ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Indoor Residual Spraying ◽  
Central India ◽  
Control Programme ◽  
Madhya Pradesh ◽  
Control Measures ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
The Impact

Background. Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) are malaria vector control measures used in India, but the development of insecticide resistance poses major impediments for effective vector control strategies. As per the guidelines of the National Vector Borne Disease Control Programme (NVBDCP), the study was conducted in 12 districts of Madhya Pradesh to generate data on insecticide resistance in malaria vectors. Methods. The susceptibility tests were conducted on adult An. culicifacies as per the WHO standard technique with wild-caught mosquitoes. The blood-fed female mosquitoes were exposed in 3 to 4 replicates on each occasion to the impregnated papers with specified discriminating dosages of the insecticides (DDT: 4%, malathion: 5%, deltamethrin: 0.05%, and alphacypermethrin: 0.05%), for one hour, and mortality was recorded after 24-hour holding. Results. An. culicifacies was found resistant to DDT 4% in all the 12 districts and malathion in 11 districts. The resistance to alphacypermethrin was also observed in two districts, and possible resistance was found to alphacypermethrin in seven districts and to deltamethrin in eight districts, while the vector was found susceptible to both deltamethrin and alphacypermethrin in only 3 districts. Conclusion. An. culicifacies is resistant to DDT and malathion and has emerging resistance to pyrethroids, alphacypermethrin, and deltamethrin. Therefore, regular monitoring of insecticide susceptibility in malaria vectors is needed for implementing effective vector management strategies. However, studies to verify the impact of IRS with good coverage on the transmission of disease are required before deciding on the change of insecticide in conjunction with epidemiological data.

scholarly journals Quantifying and characterizing hourly human exposure to malaria vectors bites to address residual malaria transmission during dry and rainy seasons in rural Southwest Burkina Faso

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
D. D. Soma ◽  
B. Zogo ◽  
P. Taconet ◽  
A. Somé ◽  
S. Coulibaly ◽  
...  
Keyword(s):  
Burkina Faso ◽  
Malaria Transmission ◽  
Rural Area ◽  
Malaria Vector ◽  
Human Exposure ◽  
World Health ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Residual Malaria Transmission ◽  
Dry And Rainy Seasons

Abstract Background To sustain the efficacy of malaria vector control, the World Health Organization (WHO) recommends the combination of effective tools. Before designing and implementing additional strategies in any setting, it is critical to monitor or predict when and where transmission occurs. However, to date, very few studies have quantified the behavioural interactions between humans and Anopheles vectors in Africa. Here, we characterized residual transmission in a rural area of Burkina Faso where long lasting insecticidal nets (LLIN) are widely used. Methods We analysed data on both human and malaria vectors behaviours from 27 villages to measure hourly human exposure to vector bites in dry and rainy seasons using a mathematical model. We estimated the protective efficacy of LLINs and characterised where (indoors vs. outdoors) and when both LLIN users and non-users were exposed to vector bites. Results The percentage of the population who declared sleeping under a LLIN the previous night was very high regardless of the season, with an average LLIN use ranging from 92.43 to 99.89%. The use of LLIN provided > 80% protection against exposure to vector bites. The proportion of exposure for LLIN users was 29–57% after 05:00 and 0.05–12% before 20:00. More than 80% of exposure occurred indoors for LLIN users and the estimate reached 90% for children under 5 years old in the dry cold season. Conclusions LLINs are predicted to provide considerable protection against exposure to malaria vector bites in the rural area of Diébougou. Nevertheless, LLIN users are still exposed to vector bites which occurred mostly indoors in late morning. Therefore, complementary strategies targeting indoor biting vectors in combination with LLIN are expected to be the most efficient to control residual malaria transmission in this area.

scholarly journals 20-Hydroxyecdysone (20E) signaling as a promising target for the chemical control of malaria vectors

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Elodie Ekoka ◽  
Surina Maharaj ◽  
Luisa Nardini ◽  
Yael Dahan-Moss ◽  
Lizette L. Koekemoer
Keyword(s):  
Vector Control ◽  
Signaling Pathway ◽  
Malaria Vector ◽  
Vector Competence ◽  
Rapid Development ◽  
World Health ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Insect Growth Regulators ◽  
Vector Abundance

AbstractWith the rapid development and spread of resistance to insecticides among anopheline malaria vectors, the efficacy of current World Health Organization (WHO)-approved insecticides targeting these vectors is under threat. This has led to the development of novel interventions, including improved and enhanced insecticide formulations with new targets or synergists or with added sterilants and/or antimalarials, among others. To date, several studies in mosquitoes have revealed that the 20-hydroxyecdysone (20E) signaling pathway regulates both vector abundance and competence, two parameters that influence malaria transmission. Therefore, insecticides which target 20E signaling (e.g. methoxyfenozide and halofenozide) may be an asset for malaria vector control. While such insecticides are already commercially available for lepidopteran and coleopteran pests, they still need to be approved by the WHO for malaria vector control programs. Until recently, chemicals targeting 20E signaling were considered to be insect growth regulators, and their effect was mostly studied against immature mosquito stages. However, in the last few years, promising results have been obtained by applying methoxyfenozide or halofenozide (two compounds that boost 20E signaling) to Anopheles populations at different phases of their life-cycle. In addition, preliminary studies suggest that methoxyfenozide resistance is unstable, causing the insects substantial fitness costs, thereby potentially circumventing one of the biggest challenges faced by current vector control efforts. In this review, we first describe the 20E signaling pathway in mosquitoes and then summarize the mechanisms whereby 20E signaling regulates the physiological processes associated with vector competence and vector abundance. Finally, we discuss the potential of using chemicals targeting 20E signaling to control malaria vectors.

scholarly journals Current status of insecticide resistance in malaria vectors in the Asian countries: a systematic review

F1000Research ◽  
2022 ◽  
Vol 10 ◽  
pp. 200
Author(s):  
Dewi Susanna ◽  
Dian Pratiwi
Keyword(s):  
Systematic Review ◽  
Insecticide Resistance ◽  
Vector Control ◽  
Malaria Vector ◽  
Pyrethroid Resistance ◽  
Current Trend ◽  
Current Status ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Publication Date

Background: The application of insecticides for malaria vector control has led to a global problem, which is the current trend of increased resistance against these chemicals. This study aimed to review the insecticide resistance status was previously determined in Asia and how to implement the necessary interventions. Moreover, the implications of resistance in malaria vector control in this region were studied. Methods: This systematic review was conducted using a predefined protocol based on PRISMA-retrieved articles from four science databases, namely ProQuest, Science Direct, EBSCO, and PubMed in the last ten years (2009 to 2019). The searching process utilized four main combinations of the following keywords: malaria, vector control, insecticide, and Asia. In ProQuest, malaria control, as well as an insecticide, were used as keywords. The following criteria were included in the filter, namely full text, the source of each article, scholarly journal, Asia, and publication date as in the last ten years. Results: There were 1408 articles retrieved during the initial search (ProQuest=722, Science Direct=267, EBSCO=50, PubMed=285, and Scopus=84). During the screening, 27 articles were excluded because of duplication, 1361 based on title and abstract incompatibility with the inclusion criteria, and 20 due to content differences. In the final screening process, 15 articles were chosen to be analyzed. From the 15 articles, it is known that there was organochlorine (DDT), organophosphate (malathion), and pyrethroids resistance in several Anopheles species with a less than 80% mortality rate. Conclusion: This review found multiple resistance in several Anopheles includes resistance to pyrethroid. The reports of pyrethroid resistance were quite challenging because it is considered effective in the malaria vector control. Several countries in Asia are implementing an insecticide resistance management (IRM) strategy against malaria vectors following the Global Plan for IRM.

scholarly journals Characterization of resistance profile (intensity and mechanisms) of Anopheles gambiae in three communes of northern Benin, West Africa

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Casimir Dossou Kpanou ◽  
Hermann W. Sagbohan ◽  
Fortuné Dagnon ◽  
Germain G. Padonou ◽  
Razaki Ossè ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Gambiae ◽  
High Intensity ◽  
Mortality Rates ◽  
Detoxification Enzymes ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Biochemical Tests ◽  
Diagnostic Dose

Abstract Background The selection and the spread of insecticide resistance in malaria vectors to the main classes of insecticides used in vector control tools are a major and ongoing challenge to malaria vector control programmes. This study aimed to determine the intensity of vector resistance to insecticides in three regions of Benin with different agro-ecological characteristics. Methods Larvae of Anopheles gambiae sensu lato (s.l.) were collected from September to November 2017 in different larval sites in three northern Benin communes: Parakou, Kandi and Malanville. Two to five-day-old, non-blood-fed, female mosquitoes were exposed to papers impregnated with deltamethrin, permethrin and bendiocarb at dosages of 1 × the diagnostic dose, 5 × and 10 × to determine the intensity of resistance in these vectors. Molecular frequencies of the kdr L1014F and ace-1R G119S insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled at each study site. Results Resistance to pyrethroids (permethrin and deltamethrin) was recorded in all three communes with mortality rates below 60% using the diagnostic dose (1x). The results obtained after exposure of An. gambiae to permethrin 10 × were 99% in Kandi, 98% in Malanville and 99% in Parakou. With deltamethrin 10x, mortality rates were 100% in Kandi, 96% in Malanville and 73% in Parakou. For the diagnostic dose of bendiocarb, suspected resistance was recorded in the communes of Malanville (97%) and Kandi (94%) while sensitivity was observed in Parakou (98%).Using the 10 × dose, mortality was 98% in Kandi, 100% in Malanville and 99% in Parakou. The frequencies of the kdr L1014F allele varied between 59 and 83% depending on the sites and species of the An. gambiae complex, while the frequency of the ace-1R G119S gene varied between 0 and 5%. Biochemical tests showed high levels of oxidase and esterase activity compared to the susceptible colony strain of An. gambiae sensu stricto (Kisumu strain). Conclusion Anopheles gambiae showed a generalized loss of susceptibility to permethrin and deltamethrin but also showed moderate to high intensity of resistance in different regions of Benin. This high intensity of resistance is a potential threat to the effectiveness of vector control.

scholarly journals Mosquito feeding behavior and how it influences residual malaria transmission across Africa

2019 ◽  
Vol 116 (30) ◽  
pp. 15086-15095 ◽  
Author(s):  
Ellie Sherrard-Smith ◽  
Janetta E. Skarp ◽  
Andrew D. Beale ◽  
Christen Fornadel ◽  
Laura C. Norris ◽  
...  
Keyword(s):  
Vector Control ◽  
Indoor Residual Spraying ◽  
Malaria Prevention ◽  
Health Impact ◽  
Time Of Day ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Outdoor Biting ◽  
Residual Malaria Transmission ◽  
Year 2000

The antimalarial efficacy of the most important vector control interventions—long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS)—primarily protect against mosquitoes’ biting people when they are in bed and indoors. Mosquito bites taken outside of these times contribute to residual transmission which determines the maximum effectiveness of current malaria prevention. The likelihood mosquitoes feed outside the time of day when LLINs and IRS can protect people is poorly understood, and the proportion of bites received outdoors may be higher after prolonged vector control. A systematic review of mosquito and human behavior is used to quantify and estimate the public health impact of outdoor biting across Africa. On average 79% of bites by the major malaria vectors occur during the time when people are in bed. This estimate is substantially lower than previous predictions, with results suggesting a nearly 10% lower proportion of bites taken at the time when people are beneath LLINs since the year 2000. Across Africa, this higher outdoor transmission is predicted to result in an estimated 10.6 million additional malaria cases annually if universal LLIN and IRS coverage was achieved. Higher outdoor biting diminishes the cases of malaria averted by vector control. This reduction in LLIN effectiveness appears to be exacerbated in areas where mosquito populations are resistant to insecticides used in bed nets, but no association was found between physiological resistance and outdoor biting. Substantial spatial heterogeneity in mosquito biting behavior between communities could contribute to differences in effectiveness of malaria control across Africa.

Sign in / Sign up

Export Citation Format

Share Document