Abstract:BackgroundIn many African countries malaria has declined sharply due to a synergy of actions marked by the introduction of vector control strategies, but the disease remains a leading cause of morbidity and mortality in Central African Republic (CAR). An entomological study was initiated with the aim to characterize the malaria vectors in Bangui, the capital of CAR, and determine their vector competence.MethodsA cross-sectional entomological study was conducted in 15 sites of the district of Bangui, the capita… Show more
“…The presence of A. gambiae in all specimens tested is a clear indication of the dominance of this species in this region and is in agreement with the rest of CAR [16]. The same results have been observed in Equatorial Guinea [34], Gabon [35], Chad [36] and in the Democratic Republic of Congo [37].…”
Section: Discussionsupporting
confidence: 84%
“…The average annual temperature is around 26 °C, with an annual precipitation of 1,510 mm. The study sites have been described in detail elsewhere [2, 16]. Fig.…”
Section: Methodsmentioning
confidence: 99%
“…In CAR, recent entomological investigation revealed the predominance of A. gambiae in Bangui with a high prevalence of the L1014F kdr mutation [16]. However, no data are available on the current insecticide resistance using World Health Organization (WHO) bioassays in A. gambiae from CAR.…”
BackgroundKnowledge of insecticide resistance status in the main malaria vectors is an essential component of effective malaria vector control. This study presents the first evaluation of the status of insecticide resistance in Anopheles gambiae populations from Bangui, the Central African Republic.Methods
Anopheles mosquitoes were reared from larvae collected in seven districts of Bangui between September to November 2014. The World Health Organisation’s bioassay susceptibility tests to lambda-cyhalothrin (0.05%), deltamethrin (0.05%), DDT (4%), malathion (5%), fenitrothion (1%) and bendiocarb (0.1%) were performed on adult females. Species and molecular forms as well as the presence of L1014F kdr and Ace-1
R mutations were assessed by PCR. Additional tests were conducted to assess metabolic resistance status.ResultsAfter 1 h exposure, a significant difference of knockdown effect was observed between districts in all insecticides tested except deltamethrin and malathion. The mortality rate (MR) of pyrethroids group ranging from 27% (CI: 19–37.5) in Petevo to 86% (CI: 77.6–92.1) in Gbanikola; while for DDT, MR ranged from 5% (CI: 1.6–11.3) in Centre-ville to 39% (CI: 29.4–49.3) in Ouango. For the organophosphate group a MR of 100% was observed in all districts except Gbanikola where a MR of 96% (CI: 90–98.9) was recorded. The mortality induced by bendiocarb was very heterogeneous, ranging from 75% (CI: 62.8–82.8) in Yapele to 99% (CI: 84.5–100) in Centre-ville. A high level of kdr-w (L1014F) frequency was observed in all districts ranging from 93 to 100%; however, no kdr-e (L1014S) and Ace-1
R mutation were found in all tested mosquitoes. Data of biochemical analysis showed significant overexpression activities of cytochrome P450, GST and esterases in Gbanikola and Yapele (χ
2 = 31.85, df = 2, P < 0.001). By contrast, esterases activities using α and β-naphthyl acetate were significantly low in mosquitoes from PK10 and Ouango in comparison to Kisumu strain (χ
2 = 17.34, df = 2, P < 0.005).ConclusionsEvidence of resistance to DDT and pyrethroids as well as precocious emergence of resistance to carbamates were detected among A. gambiae mosquitoes from Bangui, including target-site mutations and metabolic mechanisms. The co-existence of these resistance mechanisms in A. gambiae may be a serious obstacle for the future success of malaria control programmes in this region.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1965-8) contains supplementary material, which is available to authorized users.
“…The presence of A. gambiae in all specimens tested is a clear indication of the dominance of this species in this region and is in agreement with the rest of CAR [16]. The same results have been observed in Equatorial Guinea [34], Gabon [35], Chad [36] and in the Democratic Republic of Congo [37].…”
Section: Discussionsupporting
confidence: 84%
“…The average annual temperature is around 26 °C, with an annual precipitation of 1,510 mm. The study sites have been described in detail elsewhere [2, 16]. Fig.…”
Section: Methodsmentioning
confidence: 99%
“…In CAR, recent entomological investigation revealed the predominance of A. gambiae in Bangui with a high prevalence of the L1014F kdr mutation [16]. However, no data are available on the current insecticide resistance using World Health Organization (WHO) bioassays in A. gambiae from CAR.…”
BackgroundKnowledge of insecticide resistance status in the main malaria vectors is an essential component of effective malaria vector control. This study presents the first evaluation of the status of insecticide resistance in Anopheles gambiae populations from Bangui, the Central African Republic.Methods
Anopheles mosquitoes were reared from larvae collected in seven districts of Bangui between September to November 2014. The World Health Organisation’s bioassay susceptibility tests to lambda-cyhalothrin (0.05%), deltamethrin (0.05%), DDT (4%), malathion (5%), fenitrothion (1%) and bendiocarb (0.1%) were performed on adult females. Species and molecular forms as well as the presence of L1014F kdr and Ace-1
R mutations were assessed by PCR. Additional tests were conducted to assess metabolic resistance status.ResultsAfter 1 h exposure, a significant difference of knockdown effect was observed between districts in all insecticides tested except deltamethrin and malathion. The mortality rate (MR) of pyrethroids group ranging from 27% (CI: 19–37.5) in Petevo to 86% (CI: 77.6–92.1) in Gbanikola; while for DDT, MR ranged from 5% (CI: 1.6–11.3) in Centre-ville to 39% (CI: 29.4–49.3) in Ouango. For the organophosphate group a MR of 100% was observed in all districts except Gbanikola where a MR of 96% (CI: 90–98.9) was recorded. The mortality induced by bendiocarb was very heterogeneous, ranging from 75% (CI: 62.8–82.8) in Yapele to 99% (CI: 84.5–100) in Centre-ville. A high level of kdr-w (L1014F) frequency was observed in all districts ranging from 93 to 100%; however, no kdr-e (L1014S) and Ace-1
R mutation were found in all tested mosquitoes. Data of biochemical analysis showed significant overexpression activities of cytochrome P450, GST and esterases in Gbanikola and Yapele (χ
2 = 31.85, df = 2, P < 0.001). By contrast, esterases activities using α and β-naphthyl acetate were significantly low in mosquitoes from PK10 and Ouango in comparison to Kisumu strain (χ
2 = 17.34, df = 2, P < 0.005).ConclusionsEvidence of resistance to DDT and pyrethroids as well as precocious emergence of resistance to carbamates were detected among A. gambiae mosquitoes from Bangui, including target-site mutations and metabolic mechanisms. The co-existence of these resistance mechanisms in A. gambiae may be a serious obstacle for the future success of malaria control programmes in this region.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1965-8) contains supplementary material, which is available to authorized users.
“…Point mutations in mosquitos described as Knockdown resistance (kdr) was extensively investigated to understand the molecular aspects of Anopheles mosquito resistance. Knockdown resistance (kdr) is the most common form of insecticide resistance and has been reported in many African and Asian countries [20,81,[95][96][97][98][99][100][101][102][103][104]. One of the top cited articles also discussed the role of voltage gated sodium channels in insecticide resistance.…”
BackgroundEmergence of insecticide resistance in malaria vectors is a real threat to future goals of elimination and control of malaria. Therefore, the objective of this study was to assess research trend on insecticide resistance of Anopheles mosquito. In specific, number of publications, countries, institutions, and authors’ research profile, citation analysis, international collaborations, and impact of journals publishing documents on insecticide resistance will be presented. It was conducted via Scopus search engine which was used to retrieve relevant data. Keywords used were based on literature available on this topic. The duration of study was set from 1996–2015.ResultsA total of 616 documents, mainly as original research articles (n = 569; 92.37%) were retrieved. The average number of citations per article was 26.36. Poisson log-linear regression analysis indicated that there was a 6.00% increase in the number of publications for each extra article on pyrethroid resistance. A total of 82 different countries and 1922 authors participated in publishing retrieved articles. The United Kingdom (UK) ranked first in number of publications followed by the United States of America (USA) and France. The top ten productive countries included seven African countries. The UK had collaborations mostly with Benin (relative link strength = 46). A total of 1817 institution/ organizations participated in the publication of retrieved articles. The most active institution/ organization was Liverpool School of Tropical Medicine. Retrieved articles were published in 134 different scientific peer reviewed journals. The journal that published most on this topic was Malaria Journal (n = 101; 16.4%). Four of the top active authors were from South Africa and two were from the UK. Three of the top ten cited articles were published in Insect Molecular Biology journal. Six articles were about pyrethroid resistance and at least two were about DDT resistance.ConclusionPublications on insecticide resistance in malaria vector has gained momentum in the past decade. International collaborations enhanced the knowledge about the situation of vector resistance in countries with endemic malaria. Molecular biology of insecticide resistance is the key issue in understanding and overcoming this emerging problems.
31 Background: The Madagascar National Strategic Plan for Malaria Control 2018 (NSP) outlines 32 malaria control pre-elimination strategies that include detailed goals for mosquito control. 33 Primary surveillance protocols and mosquito control interventions focus on indoor vectors of 34 malaria, while many potential vectors feed and rest outdoors. Here we describe the application of 35 novel tools that advance our understanding of diversity, host choice, and Plasmodium infection 36 in the Anopheline mosquitoes of the Western Highland Fringe of Madagascar. 37 Methodology/Principal Findings: We employed a novel outdoor trap, the QUadrant Enabled 38 Screen Trap (QUEST), in conjunction with the recently developed multiplex BLOOdmeal 39 Detection Assay for Regional Transmission (BLOODART). We captured a total of 1252 female 40 Anopheles mosquitoes (10 species), all of which were subjected to BLOODART analysis. 41 QUEST collection captured a heterogenous distribution of mosquito density, diversity, host 42 choice, and Plasmodium infection. Concordance between Anopheles morphology and 43 BLOODART species identifications ranged from 93-99%. Mosquito feeding behavior in this 44 collection frequently exhibited multiple blood meal hosts (single host = 53.6%, two hosts = 45 42.1%, three hosts = 4.3%). The overall percentage of human positive bloodmeals increased 46 between the December 2017 and the April 2018 timepoints (27% to 44%). Plasmodium 47 positivity was found primarily in vectors considered to be of secondary importance, with an 48 overall prevalence of 6%.49 Conclusions/Significance: The QUEST was an efficient tool for sampling Anopheline 50 mosquitoes. Vectors considered to be of secondary importance were commonly found with 51 Plasmodium DNA in their abdomens, indicating a need to account for these species in routine 52 surveillance efforts. Mosquitoes exhibited multiple blood feeding behavior within a gonotrophic 4 53 cycle, with predominantly non-human hosts in the bloodmeal. Taken together, this complex 54 feeding behavior could enhance the role of multiple Anopheline species in malaria transmission, 55 possibly tempered by zoophilic feeding tendencies.
57
Author Summary
58Malaria continues to be a significant threat to public health in Madagascar. Elimination of 59 this disease is impeded by numerous factors, such as vector surveillance that does little to 60 account for the potential role of secondary malaria vectors, which rest and feed outdoors. In this 61 study, we designed a novel, low cost QUadrant Enabled Screen Trap (QUEST) to address the 62 lack of traps for outdoor mosquitoes. We used this in conjunction with our novel BLOOdmeal 63 Detection Assay for Regional Transmission (BLOODART) to assess mosquito feeding behavior 64 in the Western Highland Fringe of Madagascar. Our analysis revealed significant variability in 65 mosquito density, diversity, host choice, and Plasmodium infection across traps placed within 66 and between two nearby villages at two timepoints; indicating a strong, small-scale sp...
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