scholarly journals Intensity and mechanisms of deltamethrin and permethrin resistance in Anopheles gambiae s.l. populations in southern Benin

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Hermann Watson Sagbohan ◽  
Casimir D. Kpanou ◽  
Razaki Osse ◽  
Fortuné Dagnon ◽  
Germain G. Padonou ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Detoxification Enzymes ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Resistance Allele ◽  
Resistance Mutations ◽  
The Difference ◽  
Study Sites ◽  
Insecticide Treated Bed Nets ◽  
Southern Benin

Abstract Background Insecticide resistance is threatening the effectiveness of efforts to control malaria vectors in Benin. This study explores the levels and mechanisms of insecticide resistance in An. gambiae s.l. to pyrethroids. Methods Larvae were collected from August 2017 to July 2018 in five communes in southern Benin (Adjohoun, Allada, Bohicon, Cotonou, and Porto-Novo) representing diverse ecological regions, and were reared in Benin’s insectary. Two- to five-day-old female mosquitoes from each district were exposed to multiple doses of deltamethrin and permethrin (1×, 2×, 5×, and 10×) using the WHO insecticide resistance intensity bioassay. The effect of pre-exposure to the synergist, piperonyl butoxide (PBO), was also tested at different pyrethroid doses. Molecular allele frequencies of kdr (1014F) and ace-1R (119S) insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled from each study area. Results An. gambiae s.l. were resistant to pyrethroid-only exposure up to 10× the diagnostic doses in all the study sites for both deltamethrin and permethrin. Mortality was significantly higher in An. gambiae s.l. pre-exposed to PBO followed by exposure to deltamethrin or permethrin compared to mosquitoes exposed to deltamethrin or permethrin only (p < 0.001). The difference in mortality between deltamethrin only and PBO plus deltamethrin was the smallest in Cotonou (16–64%) and the greatest in Bohicon (12–93%). The mortality difference between permethrin only and PBO plus permethrin was the smallest in Cotonou (44–75%) and the greatest in Bohicon (22–72%). In all the study sites, the kdr resistance allele (1014F) frequency was high (75–100%), while the ace-1 resistance allele (G119S) frequency was low (0–3%). Analysis of the metabolic enzymatic activity of An. gambiae s.l. showed overexpression of nonspecific esterases and glutathione S-transferases (GST) in all study sites. In contrast to the PBO results, oxidase expression was low and was similar to the susceptible An. gambiae s.s. Kisumu strain in all sites. Conclusion There is high-intensity resistance to pyrethroids in southern Benin. However, pre-exposure to PBO significantly increased susceptibility to the pyrethroids in the different An. gambiae s.l. populations sampled. The use of PBO insecticide-treated bed nets may help maintain the gains in An. gambiae (s.l.) control in southern Benin. Graphical Abstract

scholarly journals Utilization of Insecticide Treated Bed Nets (ITNs) among Caregivers of Children under Five Years in the Ho Municipality

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Kennedy Diema Konlan ◽  
Milipaak Japiong ◽  
Kennedy Dodam Konlan ◽  
Agani Afaya ◽  
Solomon Mohammed Salia ◽  
...  
Keyword(s):  
Continuous Distribution ◽  
Cross Sectional Study ◽  
Bed Nets ◽  
Cross Sectional ◽  
Effective Measure ◽  
Children Under Five ◽  
Under Five ◽  
The Difference ◽  
Multistage Sampling ◽  
Insecticide Treated Bed Nets

Background. In Ghana, attempts to control malaria through antimalarial medications are currently threatened by the emergence and spread of drug resistant malaria parasites. This, together with the increasing incidence of malaria, has heightened the need for a more effective method of controlling the spread. The use of Insecticide Treated Bed Net (ITN) has been recognised as an effective measure in the prevention of malaria. Objective/Purpose. In this study, we examined the utilisation of ITN among caregivers of children under five years in Ho municipality of Ghana. Methods. This descriptive cross-sectional study recruited 283 household representatives through a multistage sampling method. A questionnaire was used to collect the data and was analyzed using STATA version 14. Descriptive and inferential statistics were adopted in presenting the data. Results. Ownership of ITN was higher (80.7%) than its utilisation (41.7%). The age of caregiver was strongly associated with the utilisation of ITN (AOR=2.00, 95% CI=0.00, 0.02, p<0.001) among children less than five years. Caregivers aged 26-35 were 49% times less likely to use an ITN as compared to those aged between 17 and 25 and the difference was statistically significant. Conclusion. In order to ensure a high ITN coverage and utilisation, there is the need for continuous distribution of ITNs to households. Households should be sensitized to use the nets to prevent the continuous spread of malaria.

scholarly journals Exploring the Mechanisms of Multiple Insecticide Resistance in a Highly Plasmodium-Infected Malaria Vector Anopheles funestus Sensu Stricto from Sahel of Northern Nigeria

Genes ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 454
Author(s):  
Sulaiman S. Ibrahim ◽  
Muhammad M. Mukhtar ◽  
Helen Irving ◽  
Jacob M. Riveron ◽  
Amen N. Fadel ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Malaria Vector ◽  
Anopheles Funestus ◽  
Indoor Residual Spraying ◽  
Sensu Stricto ◽  
Bed Nets ◽  
Metabolic Resistance ◽  
Biting Rate ◽  
Insecticide Treated Bed Nets ◽  
Sahel Region

The Nigerian Government is scaling up the distribution of insecticide-treated bed nets for malaria control, but the lack of surveillance data, especially in the Sudan/Sahel region of the country, may hinder targeting priority populations. Here, the vectorial role and insecticide resistance profile of a population of a major malaria vector Anopheles funestus sensu stricto from Sahel of Nigeria was characterised. An. funestus s.s. was the only vector found, with a high human blood index (100%) and a biting rate of 5.3/person/night. High Plasmodium falciparum infection was discovered (sporozoite rate = 54.55%). The population is resistant to permethrin (mortality = 48.30%, LT50 = 65.76 min), deltamethrin, DDT (dichlorodiphenyltrichloroethane) and bendiocarb, with mortalities of 29.44%, 56.34% and 54.05%, respectively. Cone-bioassays established loss of efficacy of the pyrethroid-only long-lasting insecticidal nets (LLINs); but 100% recovery of susceptibility was obtained for piperonylbutoxide (PBO)-containing PermaNet®3.0. Synergist bioassays with PBO and diethyl maleate recovered susceptibility, implicating CYP450s (permethrin mortality = 78.73%, χ2 = 22.33, P < 0.0001) and GSTs (DDT mortality = 81.44%, χ2 = 19.12, P < 0.0001). A high frequency of 119F GSTe2 mutation (0.84) was observed (OR = 16, χ2 = 3.40, P = 0.05), suggesting the preeminent role of metabolic resistance. These findings highlight challenges associated with deployment of LLINs and indoor residual spraying (IRS) in Nigeria.

scholarly journals Managing insecticide resistance in malaria vectors by combining carbamate-treated plastic wall sheeting and pyrethroid-treated bed nets

2009 ◽  
Vol 8 (1) ◽  
pp. 233 ◽  
Author(s):  
Armel Djènontin ◽  
Joseph Chabi ◽  
Thierry Baldet ◽  
Seth Irish ◽  
Cédric Pennetier ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Malaria Vectors ◽  
Bed Nets

scholarly journals Status of insecticide susceptibility in Anopheles arabiensis and detection of the knockdown resistance mutation (kdr) concerning agricultural practices from Northern Sudan state, Sudan

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
M. Y. Korti ◽  
T. B. Ageep ◽  
A. I. Adam ◽  
K. B. Shitta ◽  
A. A. Hassan ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Arabiensis ◽  
Resistance Mutation ◽  
Indoor Residual Spraying ◽  
Mortality Rates ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Knockdown Resistance ◽  
Insecticide Susceptibility

Abstract Background Chemical control has been the most efficient method in mosquito control, the development of insecticide resistance in target populations has a significant impact on vector control. The use of agricultural pesticides may have a profound impact on the development of resistance in the field populations of malaria vectors. Our study focused on insecticide resistance and knockdown resistance (kdr) of Anopheles arabiensis populations from Northern Sudan, related to agricultural pesticide usage. Results Anopheles arabiensis from urban and rural localities (Merowe and Al-hamadab) were fully susceptible to bendiocarb 0.1% and permethrin 0.75% insecticides while resistant to DDT 4% and malathion 5%. The population of laboratory reference colony F189 from Dongola showed a mortality of 91% to DDT (4%) and fully susceptible to others. GLM analysis indicated that insecticides, sites, site type, and their interaction were determinant factors on mortality rates (P < 0.01). Except for malathion, mortality rates of all insecticides were not significant (P > 0.05) according to sites. Mortality rates of malathion and DDT were varied significantly (P < 0.0001 and P < 0.05 respectively) by site types, while mortality rates of bendiocarb and permethrin were not significant (P >0.05). The West African kdr mutation (L1014F) was found in urban and rural sites. Even though, the low-moderate frequency of kdr (L1014F) mutation was observed. The findings presented here for An. arabiensis showed no correlation between the resistant phenotype as ascertained by bioassay and the presence of the kdr mutation, with all individuals tested except the Merowe site which showed a moderate association with DDT (OR= 6 in allelic test), suggesting that kdr genotype would be a poor indicator of phenotypic resistance. Conclusion The results provide critical pieces of information regarding the insecticide susceptibility status of An. arabiensis in northern Sudan. The usage of the same pesticides in agricultural areas seemed to affect the Anopheles susceptibility when they are exposed to those insecticides in the field. The kdr mutation might have a less role than normally expected in pyrethroids resistance; however, other resistance genes should be in focus. These pieces of information will help to improve the surveillance system and The implication of different vector control programs employing any of these insecticides either in the treatment of bed nets or for indoor residual spraying would achieve satisfactory success rates.

scholarly journals Accounting for heterogeneity in wild adult samples to measure insecticide resistance in Anopheles malaria vectors

2021 ◽  
Author(s):  
Inga E. Holmdahl ◽  
Caroline O. Buckee ◽  
Lauren M. Childs
Keyword(s):  
Spatial Structure ◽  
Insecticide Resistance ◽  
Gold Standard ◽  
Time Frame ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Insecticide Exposure ◽  
Mosquito Collection ◽  
The Impact

Background Systematic, long-term, and spatially representative monitoring of insecticide resistance in mosquito populations is urgently needed to quantify its impact on malaria transmission, and to combat failing interventions when resistance emerges. Resistance assays on wild-caught adult mosquitoes (known as adult-capture) offer an alternative to the current protocols, and can be done cheaply, in a shorter time frame, and in the absence of an insectary. However, quantitative assessments of the performance of these assays relative to the gold standard, which involves rearing larvae in an insectary, are lacking. Methodology/Principal findings We developed a discrete-time deterministic mosquito lifecycle model to simulate insecticide resistance assays from adult-captured mosquito collection in a heterogeneous environment compared to the gold standard larval capture methods, and to quantify possible biases in the results. We incorporated non-lethal effects of insecticide exposure that have been demonstrated in laboratory experiments, spatial structure, and the impact of multiple exposure to insecticides and natural ageing on mosquito death rates during the assay. Using output from this model, we compared the results of these assays to true resistance as measured by the presence of the resistance allele. In simulated samples of 100 test mosquitoes, reflecting WHO-recommended sample sizes, we found that compared to adult-captured assays (MSE = 0.0059), larval-captured assays were a better measure of true resistance (MSE = 0.0018). Using a correction model, we were able to improve the accuracy of the adult-captured assay results (MSE = 0.0038). Bias in the adult-capture assays was dependent on the level of insecticide resistance rather than coverage of bed nets or spatial structure. Conclusions/Significance Using adult-captured mosquitoes for resistance assays has logistical advantages over the standard larval-capture collection, and may be a more accurate sample of the mosquito population. These results show that adult-captured assays can be improved using a simple mathematical approach and used to inform resistance monitoring programs.

scholarly journals Host-feeding Preference of Anopheles Species under Prolonged Use of Insecticide-treated Bed Nets in Kamuli District, Uganda: Implications for Vector Control

2020 ◽  
pp. 16-25
Author(s):  
Fredrick G. Kabbale ◽  
Anne M. Akol ◽  
John B. Kaddu ◽  
Enock Matovu ◽  
Anne Kazibwe ◽  
...  
Keyword(s):  
Vector Control ◽  
Blood Meal ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Enzyme Linked Immunosorbent Assay ◽  
Host Feeding ◽  
Bed Net ◽  
Insecticide Treated Bed Nets ◽  
Intervention Zone ◽  
Blood Meals

Background: The blood-feeding patterns are crucial in incriminating disease vectors as well as facilitating the design and consolidation of effective vector control interventions in an area.  Objective: This study aimed to establish if prolonged use of insecticide-treated bed nets (ITNs) caused a shift in the preferred hosts of the common malaria vectors as the hosts were under the bed net. Such a shift would render ITNs less effective and would probably explain the continued morbidity and mortality due to malaria in the highly endemic Kamuli district. Methods: A total of 3,519 indoor and outdoor human biting female Anopheles gambiae sensu lato and An. funestus mosquitoes were collected from 48 households using human-baited bed net traps. All 187 indoor resting blood-fed anophelines collected were tested by direct enzyme-linked immunosorbent assay (ELISA) for blood meal host identification. Of these, 73 mid guts came from 24 households in villages with a 69% ITNs coverage, while 114 mid guts were from 24 households in non-ITN villages. Results: Blood meal hosts were identified in only 10.96% (n = 8) and 14.91% (n = 17) of the Anopheles blood meals from the intervention and non-intervention zones, respectively. Other blood meals could not be clearly identified.  Eight (100%) blood meals in the intervention zone were from humans, while in the non-intervention zone, 15 (88.24%), one (5.88%) and one (5.88%) came from humans, cattle and goat, respectively. These findings demonstrated that the malaria vectors in Kamuli district are anthropophilic, with nearly all the mosquitoes collected from both zones feeding on humans during every blood meal (p = 0.82). This indicated high vector-human contacts, and thus implicating these species as important in the transmission of Plasmodium species and probably other infections. Conclusion: The use of insecticide-treated bed nets is effective for controlling malaria vectors inside houses, evoking universal coverage of houses in the area.

scholarly journals Preventive Measures Against The Vectors Of Malaria In Akanda, Southwest Gabon: Knowledge, Attitudes, Practices, And Beliefs

2021 ◽  
Vol 17 (21) ◽  
pp. 169
Author(s):  
Richard Pamba ◽  
Silas Lendzele Sevidzem ◽  
Aubin Armel Koumba ◽  
Christophe Roland Zinga-Koumba ◽  
Audrey Prisca Melodie Ovono ◽  
...  
Keyword(s):  
Preventive Measures ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Literacy Rate ◽  
Beliefs And Practices ◽  
Age Cohorts ◽  
Insecticide Treated Bed Nets

Background: Reliable data on the Knowledge, Attitudes, Beliefs, and Practices (KABP) of the indigenes of Akanda and its environs on the different approaches to fight against vectors of malaria is lacking. Objective: To evaluate the KABP of the indigenes of Akanda and its environs on the different techniques used to fight against vectors of malaria. Materials and Methods: A cross sectional survey using semi-structured questionnaires was conducted on heads of randomly selected households at Akanda from April to June 2019. Results: We interviewed 369 heads of households and the population had a high literacy rate. It was noticed that 94% of respondents knew that mosquitoes could transmit malaria. More than 80% believed that Insecticide-Treated bed Nets (ITNs) could protect them from malaria infection. There was no preference in ITNs usage with age cohorts and seasons of the year. The ITNs owned by respondents were mostly purchased from shops. Respondents underlined that their reluctance to sleep under ITNs was because of their inability to breath under such conditions. Also, apart from the use of ITNs for malaria control, Indoor Residual Spraying (IRS) using insecticides (mostly Rambo®) purchased from shops and cleaning around house surroundings were practiced by >50% of respondents. Conclusion: Despite respondent’s awareness of mosquitoes as vectors of malaria as well as the use of ITNs, IRS, and cleaning of home surroundings to reduce malaria vectors burden, the ITNs coverage rate is very weak and more sensitization is also required at Akanda in Gabon.

scholarly journals Activity of Cytochrome P450 Monooxygenase (CYPs) Metabolic Enzymes as Markers of Insecticide Resistance in Anopheles vagus Muara Enim Mosquitoes, Indonesia

2021 ◽  
Vol 5 (2) ◽  
pp. 305-311
Author(s):  
Dalilah ◽  
Muhaimin Ramdja ◽  
Dwi Handayani ◽  
Lasbudi P Ambarita ◽  
R. Irpan Pahlepi ◽  
...  
Keyword(s):  
Biochemical Test ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Synthetic Pyrethroids ◽  
Elisa Method ◽  
P450 Monooxygenase ◽  
Collection Method ◽  
Anopheles Mosquitoes ◽  
Insecticide Treated Bed Nets ◽  
Anopheles Vagus

A B S T R A C TThe use of synthetic pyrethroids in insecticide-treated bed nets (LLINs) and sprayform (IRS) has been carried out since 2012 in Muara Emil Village and since 2016 inall villages in Tanjung Agung District, Muara Enim Regency. Biochemical resistancecan occur to the enzymes that play a role in detoxifying the insecticide. This studyaims to identify whether there is an increase in the levels of the enzyme CytochromeP450 monooxygenase (CYPs) through the enzyme biochemical test on the malariavector mosquito Anopheles vagus originating from Pagar Dewa Village and MuaraEmil Village, Muara Enim Regency. The sample of female Anopheles mosquitoes wasnot full. Blood was taken at night using the resting collection method. Mosquitoesthat have been identified as Anopheles vagus species are used to check CYPs enzymelevels using the ELISA method. The results of the biochemical test showed thatenzyme levels increased from the Muara emil and Pagar Dewa village mosquitoeswith a percentage of 71% and 61.53% (with cut off point OD> 0.165). The value ofCYPs enzyme levels for mosquitoes from Muara Emil village was higher than that ofthe mosquitoes from Pagar Dewa Village (mean 0.005027 ± 0.007). The increasedactivity of the CYPs enzyme plays a role in the detoxification of synthetic pyrethroidinsecticides that can cause resistance. The high levels of enzymes from the villagesof Muara Emil and Desa Farah Dewa are in line with intensive insecticide exposurein eradicating malaria vectors in the highest malaria transmission areas in MuaraEnim Regency.

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.

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