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Caputo B, De Marco CM, Pichler V, Bottà G, Bennett KL, Clarkson CS, Tennessen JA, Weetman D, Miles A, Torre AD. Speciation within the Anopheles gambiae complex: high-throughput whole genome sequencing reveals evidence of a putative new cryptic taxon in 'far-west' Africa. RESEARCH SQUARE 2024:rs.3.rs-3914444. [PMID: 38562903 PMCID: PMC10984024 DOI: 10.21203/rs.3.rs-3914444/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The two main Afrotropical malaria vectors - Anopheles coluzzii and An. gambiae - are genetically distinct and reproductively isolated across West Africa. However, populations at the western extreme of their range are assigned as "intermediate" between the two species by whole genome sequence (WGS) data, and as hybrid forms by conventional molecular diagnostics. By exploiting WGS data from 1,190 specimens collected across west Africa via the Anopheles gambiae 1000 Genomes network, we identify a novel putative taxon in the far-west (provisionally named Bissau molecular form), which did not arise by admixture but rather originated at the same time as the split between An. coluzzii and An. gambiae. Intriguingly, these populations lack insecticide resistance mechanisms commonly observed in the two main species. These findings lead to a change of perspective on malaria vector species in the far-west region with potential for epidemiological implications, and a new challenge for genetic-based mosquito control approaches.
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Affiliation(s)
- B Caputo
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome Italy
| | - C M De Marco
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome Italy
| | - V Pichler
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome Italy
| | - G Bottà
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome Italy
| | - K L Bennett
- Wellcome Sanger Genomic Surveillance Unit, Wellcome Sanger Institute, Hinxton, Cambridge, UK
| | - C S Clarkson
- Wellcome Sanger Genomic Surveillance Unit, Wellcome Sanger Institute, Hinxton, Cambridge, UK
| | - J A Tennessen
- Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
| | - D Weetman
- Liverpool School of Tropical Medicine, Liverpool, UK
| | - A Miles
- Wellcome Sanger Genomic Surveillance Unit, Wellcome Sanger Institute, Hinxton, Cambridge, UK
| | - A Della Torre
- Dipartimento di Sanità Pubblica e Malattie Infettive, Istituto Pasteur Italia-Fondazione Cenci-Bolognetti, Università di Roma "Sapienza", Rome Italy
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Oboh MA, Asmorom N, Falade C, Ojurongbe O, Thomas BN. High genetic and haplotype diversity in vaccine candidate Pfceltos but not Pfrh5 among malaria-infected children in Ibadan, Nigeria. PeerJ 2023; 11:e16519. [PMID: 38099304 PMCID: PMC10720411 DOI: 10.7717/peerj.16519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 11/03/2023] [Indexed: 12/17/2023] Open
Abstract
Malaria remains a global public health challenge. The disease has a great impact in sub-Saharan Africa among children under five years of age and pregnant women. Malaria control programs targeting the parasite and mosquitoes vectors with combinational therapy and insecticide-treated bednets are becoming obsolete due to the phenomenon of resistance, which is a challenge for reducing morbidity and mortality. Malaria vaccines would be effective alternative to the problem of parasite and insecticide resistance, but focal reports of polymorphisms in malaria candidate antigens have made it difficult to design an effective malaria vaccine. Therefore, studies geared towards elucidating the polymorphic pattern and how genes targeted for vaccine design evolve are imperative. We have carried out molecular and genetic analysis of two genes encoding vaccine candidates-the Plasmodium falciparum cell traversal ookinetes and sporozoites (Pfceltos) and P. falciparum reticulocyte binding protein 5 (Pfrh5) in parasite isolates from malaria-infected children in Ibadan, Nigeria to evaluate their genetic diversity, relatedness and pattern of molecular evolution. Pfceltos and Pfrh5 genes were amplified from P. falciparum positive samples. Amplified fragments were purified and sequenced using the chain termination method. Post-sequence edit of fragments and application of various population genetic analyses was done. We observed a higher number of segregating sites and haplotypes in the Pfceltos than in Pfrh5 gene, the former also presenting higher haplotype (0.942) and nucleotide diversity (θ = 0.01219 and π = 0.01148). In contrast, a lower haplotype (0.426) and nucleotide diversity (θ = 0.00125; π = 0.00095) was observed in the Pfrh5 gene. Neutrality tests do not show deviation from neutral expectations for Pfceltos, with the circulation of multiple low frequency haplotypes (Tajima's D = -0.21637; Fu and Li's D = -0.08164; Fu and Li's F = -0.14051). Strong linkage disequilibrium was observed between variable sites, in each of the genes studied. We postulate that the high diversity and circulation of multiple haplotypes has the potential of making a Pfceltos-subunit vaccine ineffective, while the low genetic diversity of Pfrh5 gene substantiates its evolutionary conservation and potential as a malaria vaccine candidate.
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Affiliation(s)
- Mary Aigbiremo Oboh
- Biomedical Sciences, Rochester Institute of Technology, Rochester, NY, United States of America
| | - Naemy Asmorom
- Biomedical Sciences, Rochester Institute of Technology, Rochester, NY, United States of America
| | - Catherine Falade
- Pharmacology and Therapeutics, University of Ibadan, Ibadan, Oyo, Nigeria
| | - Olusola Ojurongbe
- Medical Microbiology and Parasitology, Ladoke Akintola University of Technology, Ogbomosho, Osun, Nigeria
- Centre for Emerging and Re-emerging Infectious Diseases, Ladoke Akintola University of Technology, Ogbomosho, Oyo, Nigeria
| | - Bolaji N. Thomas
- Biomedical Sciences, Rochester Institute of Technology, Rochester, NY, United States of America
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Badzohre A, Oshaghi MA, Enayati AA, Moosa-Kazemi SH, Nikookar SH, Talebzadeh F, Naseri-Karimi N, Hanafi-Bojd AA, Vatandoost H. Ace-1 Target Site Status and Metabolic Detoxification Associated with Bendiocarb Resistance in the Field Populations of Main Malaria Vector, Anopheles stephensi in Iran. J Arthropod Borne Dis 2023; 17:272-286. [PMID: 38860197 PMCID: PMC11162546 DOI: 10.18502/jad.v17i3.14987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 05/20/2023] [Indexed: 06/12/2024] Open
Abstract
Background Anopheles stephensi is the main vector of malaria in Iran. This study aimed to determine the susceptibility of An. stephensi from the south of Iran to bendiocarb and to investigate biochemical and molecular resistance mechanisms in this species. Methods Wild An. stephensi were collected from Hormozgan Province and reared to the adult stage. The susceptibility test was conducted according to the WHO protocols using bendiocarb impregnated papers supplied by WHO. Also, field An. Stephensi specimens were collected from south of Kerman and Sistan and Baluchistan Provinces. To determine the G119S mutation in the acetylcholinesterase (Ace1) gene, PCR-RFLP using AluI restriction enzyme and PCR direct-sequencing were performed for the three field populations and compared with the available GenBank data. Also, biochemical assays were performed to measure alpha and beta esterases, insensitive acetylcholinesterase, and oxidases in the strains. Results The bioassay tests showed that the An. stephensi field strain was resistant to bendiocarb (mortality rate 89%). Ace1 gene analysis revealed no G119S in the three field populations. Blast search of sequences revealed 98-99% identity with the Ace1 gene from Pakistan and India respectively. Also, the results of biochemical tests revealed the high activity of non-sensitive acetylcholinesterase, alpha and beta-esterase in the resistant strain compared to the susceptible strain. No G119S was detected in this study additionally the enhanced enzyme activity of esterases and acetylcholinesterase suggesting that resistance was metabolic. Conclusion The use of alternative malaria control methods and the implementation of resistance management strategies are suggested in the study area.
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Affiliation(s)
- Abdollah Badzohre
- Department of Vector Biology and Control of Diseases, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Ali Oshaghi
- Department of Vector Biology and Control of Diseases, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Ahmad Ali Enayati
- Department of Medical Entomology and Vector Control, School of Public Health and Health Sciences Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Seyed Hassan Moosa-Kazemi
- Department of Vector Biology and Control of Diseases, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed Hassan Nikookar
- Department of Medical Entomology and Vector Control, Health Sciences Research Center, Addiction Institute, School of Public Health, Mazandaran University of Medical Sciences, Sari, Iran
| | - Fahimeh Talebzadeh
- Department of Vector Biology and Control of Diseases, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Nazanin Naseri-Karimi
- Department of Vector Biology and Control of Diseases, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Ahmad Ali Hanafi-Bojd
- Department of Vector Biology and Control of Diseases, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Hassan Vatandoost
- Department of Vector Biology and Control of Diseases, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- Department of Chemical Pollutants and Pesticides, Institute of Environmental Research, Tehran University of Medical Sciences, Tehran, Iran
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N'Dri BP, Wipf NC, Saric J, Fodjo BK, Raso G, Utzinger J, Müller P, Mouhamadou CS. Species composition and insecticide resistance in malaria vectors in Ellibou, southern Côte d'Ivoire and first finding of Anopheles arabiensis in Côte d'Ivoire. Malar J 2023; 22:93. [PMID: 36915098 PMCID: PMC10010045 DOI: 10.1186/s12936-023-04456-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 01/16/2023] [Indexed: 03/16/2023] Open
Abstract
BACKGROUND Knowing the species composition and insecticide resistance status of the target vector population is important to guide malaria vector control. The aim of this study was to characterize the malaria vector population in terms of species composition, insecticide susceptibility status and potential underlying resistance mechanisms in Ellibou, southern Côte d'Ivoire. METHODS A 1-year longitudinal entomological survey was conducted using light traps and pyrethroid spray catches to sample adult mosquitoes in combination with larval sampling. The susceptibility status of Anopheles gambiae sensu lato (s.l.) to bendiocarb, deltamethrin, DDT and malathion was assessed using the World Health Organization insecticide susceptibility test. Additionally, An. gambiae specimens were screened for knockdown (kdr) and acetylcholineesterase (ace1) target site resistance alleles, and the expression levels of eight metabolic resistance genes, including seven cytochrome P450 monooxygenases (P450s) and one glutathione S-transferase (GST), measured with reverse transcription quantitative real-time polymerase chain reaction (qPCR). RESULTS Overall, 2383 adult mosquitoes from 12 different taxa were collected with Culex quinquefasciatus and An. gambiae being the predominant taxa. Molecular identification of An. gambiae s.l. revealed the presence of Anopheles arabiensis, Anopheles coluzzii, An. gambiae sensu stricto (s.s.) and Anopheles coluzzii/An. gambiae s.s. hybrids. Anopheles gambiae mosquitoes were resistant to all insecticides except malathion. PCR diagnostics revealed the presence of ace1-G280S and the kdr L995F, L995S and N1570Y target-site mutations. Additionally, several genes were upregulated, including five P450s (i.e., CYP6P3, CYP6M2, CYP9K1, CYP6Z1, CYP6P1) and GSTE2. CONCLUSION This is the first documented presence of An. arabiensis in Côte d'Ivoire. Its detection - together with a recent finding further north of the country - confirms its existence in the country, which is an early warning sign, as An. arabiensis shows a different biology than the currently documented malaria vectors. Because the local An. gambiae population was still susceptible to malathion, upregulation of P450s, conferring insecticide resistance to pyrethroids, together with the presence of ace1, suggest negative cross-resistance. Therefore, organophosphates could be an alternative insecticide class for indoor residual spraying in the Ellibou area, while additional tools against the outdoor biting An. arabiensis will have to be considered.
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Affiliation(s)
- Bédjou P N'Dri
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire. .,Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland. .,University of Basel, 4001, Basel, Switzerland.
| | - Nadja C Wipf
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Jasmina Saric
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Behi K Fodjo
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire
| | - Giovanna Raso
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Pie Müller
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Chouaïbou S Mouhamadou
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire.,North Carolina State University, Raleigh, NC, 27695-7508, USA
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Hamid-Adiamoh M, Jabang AMJ, Opondo KO, Ndiath MO, Assogba BS, Amambua-Ngwa A. Distribution of Anopheles gambiae thioester-containing protein 1 alleles along malaria transmission gradients in The Gambia. Malar J 2023; 22:89. [PMID: 36899431 PMCID: PMC9999626 DOI: 10.1186/s12936-023-04518-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 02/28/2023] [Indexed: 03/12/2023] Open
Abstract
BACKGROUND Thioester-containing protein 1 (TEP1) is a highly polymorphic gene playing an important role in mosquito immunity to parasite development and associated with Anopheles gambiae vectorial competence. Allelic variations in TEP1 could render mosquito either susceptible or resistant to parasite infection. Despite reports of TEP1 genetic variations in An. gambiae, the correlation between TEP1 allelic variants and transmission patterns in malaria endemic settings remains unclear. METHODS TEP1 allelic variants were characterized by PCR from archived genomic DNA of > 1000 An. gambiae mosquitoes collected at 3 time points between 2009 and 2019 from eastern Gambia, where malaria transmission remains moderately high, and western regions with low transmission. RESULTS Eight common TEP1 allelic variants were identified at varying frequencies in An. gambiae from both transmission settings. These comprised the wild type TEP1, homozygous susceptible genotype, TEP1s; homozygous resistance genotypes: TEP1rA and TEP1rB, and the heterozygous resistance genotypes: TEP1srA, TEP1srB, TEP1rArB and TEP1srArB. There was no significant disproportionate distribution of the TEP1 alleles by transmission setting and the temporal distribution of alleles was also consistent across the transmission settings. TEP1s was the most common in all vector species in both settings (allele frequencies: East = 21.4-68.4%. West = 23.5-67.2%). In Anopheles arabiensis, the frequency of wild type TEP1 and susceptible TEP1s was significantly higher in low transmission setting than in high transmission setting (TEP1: Z = - 4.831, P < 0.0001; TEP1s: Z = - 2.073, P = 0.038). CONCLUSIONS The distribution of TEP1 allele variants does not distinctly correlate with malaria endemicity pattern in The Gambia. Further studies are needed to understand the link between genetic variations in vector population and transmission pattern in the study settings. Future studies on the implication for targeting TEP1 gene for vector control strategy such as gene drive systems in this settings is also recommended.
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Affiliation(s)
- Majidah Hamid-Adiamoh
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia.
| | - Abdoulie Mai Janko Jabang
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Kevin Ochieng Opondo
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Mamadou Ousmane Ndiath
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Benoit Sessinou Assogba
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Alfred Amambua-Ngwa
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
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Ahmad A, Mohammed NI, Joof F, Affara M, Jawara M, Abubakar I, Okebe J, Ceesay S, Hamid-Adiamoh M, Bradley J, Amambua-Ngwa A, Nwakanma D, D'Alessandro U. Asymptomatic Plasmodium falciparum carriage and clinical disease: a 5-year community-based longitudinal study in The Gambia. Malar J 2023; 22:82. [PMID: 36882754 PMCID: PMC9993664 DOI: 10.1186/s12936-023-04519-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 02/28/2023] [Indexed: 03/09/2023] Open
Abstract
BACKGROUND Carriers of persistent asymptomatic Plasmodium falciparum infections constitute an infectious reservoir that maintains malaria transmission. Understanding the extent of carriage and characteristics of carriers specific to endemic areas could guide use of interventions to reduce infectious reservoir. METHODS In eastern Gambia, an all-age cohort from four villages was followed up from 2012 to 2016. Each year, cross-sectional surveys were conducted at the end of the malaria transmission season (January) and just before the start of the next one (June) to determine asymptomatic P. falciparum carriage. Passive case detection was conducted during each transmission season (August to January) to determine incidence of clinical malaria. Association between carriage at the end of the season and at start of the next one and the risk factors for this were assessed. Effect of carriage before start of the season on risk of clinical malaria during the season was also examined. RESULTS A total of 1403 individuals-1154 from a semi-urban village and 249 from three rural villages were enrolled; median age was 12 years (interquartile range [IQR] 6, 30) and 12 years (IQR 7, 27) respectively. In adjusted analysis, asymptomatic P. falciparum carriage at the end of a transmission season and carriage just before start of the next one were strongly associated (adjusted odds ratio [aOR] = 19.99; 95% CI 12.57-31.77, p < 0.001). The odds of persistent carriage (i.e. infected both in January and in June) were higher in rural villages (aOR = 13.0; 95% CI 6.33-26.88, p < 0.001) and in children aged 5-15 years (aOR = 5.03; 95% CI 2.47-10.23, p = < 0.001). In the rural villages, carriage before start of the season was associated with a lower risk of clinical malaria during the season (incidence risk ratio [IRR] 0.48, 95% CI 0.27-0.81, p = 0.007). CONCLUSIONS Asymptomatic P. falciparum carriage at the end of a transmission season strongly predicted carriage just before start of the next one. Interventions that clear persistent asymptomatic infections when targeted at the subpopulation with high risk of carriage may reduce the infectious reservoir responsible for launching seasonal transmission.
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Affiliation(s)
- Abdullahi Ahmad
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia.
- Global Health Institute, University of Antwerp, Gouverneur Kinsbergencentrum, Campus Drie Eiken, Doornstraat 331, 2610, Wilrijk, Belgium.
| | - Nuredin Ibrahim Mohammed
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Fatou Joof
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Muna Affara
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Musa Jawara
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Ismaela Abubakar
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Joseph Okebe
- International Public Health Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Serign Ceesay
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Majidah Hamid-Adiamoh
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Alfred Amambua-Ngwa
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Davis Nwakanma
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia.
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
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Soumare HM, Dabira ED, Camara MM, Jadama L, Gaye PM, Kanteh S, Jawara EA, Njie AK, Sanneh F, Ndiath MO, Lindsay SW, Conteh B, Ceesay S, Mohammed N, Ooko M, Bradley J, Drakeley C, Erhart A, Bousema T, D'Alessandro U. Entomological impact of mass administration of ivermectin and dihydroartemisinin-piperaquine in The Gambia: a cluster-randomized controlled trial. Parasit Vectors 2022; 15:435. [PMID: 36397132 PMCID: PMC9673448 DOI: 10.1186/s13071-022-05557-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 10/16/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Vector control interventions in sub-Saharan Africa rely on insecticide-treated nets and indoor residual spraying. Insecticide resistance, poor coverage of interventions, poor quality nets and changes in vector behavior threaten the effectiveness of these interventions and, consequently, alternative tools are needed. Mosquitoes die after feeding on humans or animals treated with ivermectin (IVM). Mass drug administration (MDA) with IVM could reduce vector survival and decrease malaria transmission. The entomological impact of MDA of combined IVM and dihydroartemisinin-piperaquine was assessed in a community-based, cluster-randomized trial. METHODS A cluster-randomized trial was implemented in 2018 and 2019 in 32 villages in the Upper River Region, The Gambia. The with the inhabitants of 16 intervention villages eligible to receive three monthly rounds of MDA at the beginning of the malaria transmission season. Entomological surveillance with light traps and human landing catches (HLC) was carried out during a 7- to 14-day period after each round of MDA, and then monthly until the end of the year. The mosquitocidal effect of IVM was determined by direct membrane feeding assays. RESULTS Of the 15,017 mosquitoes collected during the study period, 99.65% (n = 14,965) were Anopheles gambiae sensu lato (An. gambiae s.l.), comprising Anopheles arabiensis (56.2%), Anopheles coluzzii (24.5%), Anopheles gambiae sensu stricto (An. gembiae s.s.; 16.0%) and Anopheles funestus sensu lato (An. funestus s.l.; 0.35%). No effect of the intervention on vector parity was observed. Vector density determined on light trap collections was significantly lower in the intervention villages in 2019 (adjusted incidence rate ratio: 0.39; 95% confidence interval [CI]: 0.20, 0.74; P = 0.005) but not in 2018. However, vector density determined in HLC collections was similar in both the intervention and control villages. The entomological inoculation rate was significantly lower in the intervention villages than in the control villages (odds ratio: 0.36, 95% CI: 0.19, 0.70; P = 0·003). Mosquito mortality was significantly higher when blood fed on IVM-treated individuals up to 21 days post-treatment, particularly in adults and individuals with a higher body mass index. CONCLUSION Mass drug administration with IVM decreased vector density and the entomological inoculation rate while the effect on vector parity was less clear. Survival of mosquitoes fed on blood collected from IVM-treated individuals was significantly lower than that in mosquitoes which fed on controls. The influence of host characteristics on mosquito survivorship indicated that dose optimization could improve IVM efficacy. Future detailed entomological evaluation trials in which IVM is administered as stand-alone intervention may elucidate the contribution of this drug to the observed reduction in transmission.
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Affiliation(s)
- Harouna M Soumare
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia.
| | - Edgard Diniba Dabira
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Muhammed M Camara
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Lamin Jadama
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Pa Modou Gaye
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Sainey Kanteh
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Ebrima A Jawara
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Amie Kolleh Njie
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Fatou Sanneh
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Mamadou Ousman Ndiath
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | | | - Bakary Conteh
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Sainey Ceesay
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Nuredin Mohammed
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Michael Ooko
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris Drakeley
- Faculty of Infectious & Tropical Diseases, The London School of Hygiene and Tropical Medicine, London, UK
| | - Annette Erhart
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
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Oboh MA, Isaac C, Schroeter MN, Morenikeji OB, Amambua-Ngwa A, Meremikwu MM, Thomas BN. Population genetic analysis of Plasmodium falciparum cell-traversal protein for ookinetes and sporozoite among malaria patients from southern Nigeria. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2022; 105:105369. [PMID: 36182066 DOI: 10.1016/j.meegid.2022.105369] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 09/12/2022] [Accepted: 09/20/2022] [Indexed: 11/27/2022]
Abstract
Plasmodium falciparum immune escape mechanisms affect antigens being prioritized for vaccine design. As a result of the multiple surface antigens the parasite exhibits at different life cycle stages, designing a vaccine that would efficiently boost the immune system in clearing infections has been challenging. The P. falciparum cell-traversal protein for ookinetes and sporozoite (Pfceltos) is instrumental for ookinete traversal of the mosquito midgut and sporozoites invasion of the human liver cells. Pfceltos elicits both humoral and cellular immune response but has been reported with multiple single nucleotide polymorphisms in global isolates. A cross-sectional survey, conducted in southern Nigeria, between January-March 2021 recruited 283 individuals. Of this, 166 demonstrated P. falciparum infections (86 from Cross River and 80 from Edo), 48 (55.8%) while only 36 (45%) were amplified for Pfceltos gene from both sites respectively. Fifty amplified samples were sequenced and analysed for their diversity, polymorphisms and population structure of the gene. The number of segregating sites in Edo State was higher (34) than that of Cross River State. Though nucleotide diversity was higher for Edo compared to Cross River State (θw = 0.02505; π = 0.03993 versus θw = 0.00930; π = 0.01033 respectively), the reverse was the case for haplotype diversity (0.757 versus 0.890 for Edo and Cross River respectively). Of the twelve haplotypes observed from both states, only two (KASLPVEK and NAFLSFEK) were shared, with haplotype prevalence higher in Edo (16% and 36%) than Cross River (8% and 4%). The Tajima's D test was positive for both states, with Fst value showing a strong genetic differentiation (Fst = 0.25599), indicating the occurrence of balancing selection favoring haplotype circulation at a low frequency. The shared haplotypes, low Hst and Fst values presents a challenge to predict the extent of gene flow. High LD values present a grim public health consequence should a Pfceltos-conjugated vaccine be considered for prophylaxis in Nigeria.
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Affiliation(s)
- Mary A Oboh
- Department of Biomedical Sciences, Rochester Institute of Technology, Rochester, NY, United States of America.
| | - Clement Isaac
- Department of Zoology, Faculty of Life Sciences, Ambrose Ali University, Ekpoma, Nigeria
| | - Marissa N Schroeter
- Department of Biomedical Sciences, Rochester Institute of Technology, Rochester, NY, United States of America
| | - Olanrewaju B Morenikeji
- Division of Biological and Health Sciences, University of Pittsburgh, Bradford, PA 16701, United States of America
| | - Alfred Amambua-Ngwa
- Medical Research Council Unit, The Gambia, at the London School of Hygiene and Tropical Medicine, Fajara, the Gambia
| | - Martin M Meremikwu
- University of Calabar Teaching Hospital, Calabar, Cross River State, Nigeria
| | - Bolaji N Thomas
- Department of Biomedical Sciences, Rochester Institute of Technology, Rochester, NY, United States of America.
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9
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Homology Modeling and Molecular Docking Approaches for the Proposal of Novel Insecticides against the African Malaria Mosquito ( Anopheles gambiae). MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27123846. [PMID: 35744972 PMCID: PMC9227062 DOI: 10.3390/molecules27123846] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/03/2022] [Accepted: 06/10/2022] [Indexed: 11/29/2022]
Abstract
Vector-borne infectious diseases are responsible for the deaths of over 700,000 people annually, than 400,000 of them resulting from malaria. The mosquito Anopheles gambiae is one of the dominant vector species of human malaria transmission. A significant issue of the conventional insecticides which target the arthropod borne infectious diseases is their induced resistance. To overcome this inconvenience, insecticides with new modes of action are required. One of the most promising targets for the development of new potential insecticides as evidenced by current studies is the D1-like dopamine receptor (DAR). To get a deeper understanding of the structural information of this receptor, the 3D homology model was built. The possible sites within the protein were identified and the most probable binding site was highlighted. The homology model along with a series of DAR antagonists with known activity against Anopheles gambiae larvae were used in docking experiments to gain insight into their intermolecular interactions. Furthermore, virtual screening of the natural compounds from the SPECS database led to the prediction of toxicity and environmental hazards for one potential new insecticide against the Anopheles gambiae mosquito.
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Doumbe-Belisse P, Kopya E, Ngadjeu CS, Sonhafouo-Chiana N, Talipouo A, Djamouko-Djonkam L, Awono-Ambene HP, Wondji CS, Njiokou F, Antonio-Nkondjio C. Urban malaria in sub-Saharan Africa: dynamic of the vectorial system and the entomological inoculation rate. Malar J 2021; 20:364. [PMID: 34493280 PMCID: PMC8424958 DOI: 10.1186/s12936-021-03891-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/20/2021] [Indexed: 12/11/2022] Open
Abstract
Sub-Saharan Africa is registering one of the highest urban population growth across the world. It is estimated that over 75% of the population in this region will be living in urban settings by 2050. However, it is not known how this rapid urbanization will affect vector populations and disease transmission. The present study summarizes findings from studies conducted in urban settings between the 1970s and 2020 to assess the effects of urbanization on the entomological inoculation rate pattern and anopheline species distribution. Different online databases such as PubMed, ResearchGate, Google Scholar, Google were screened. A total of 90 publications were selected out of 1527. Besides, over 200 additional publications were consulted to collate information on anopheline breeding habitats and species distribution in urban settings. The study confirms high malaria transmission in rural compared to urban settings. The study also suggests that there had been an increase in malaria transmission in most cities after 2003, which could also be associated with an increase in sampling, resources and reporting. Species of the Anopheles gambiae complex were the predominant vectors in most urban settings. Anopheline larvae were reported to have adapted to different aquatic habitats. The study provides updated information on the distribution of the vector population and the dynamic of malaria transmission in urban settings. The study also highlights the need for implementing integrated control strategies in urban settings.
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Affiliation(s)
- P Doumbe-Belisse
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - E Kopya
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - C S Ngadjeu
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - N Sonhafouo-Chiana
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Health Sciences, University of Buea, Cameroon, P.O. Box 63, Buea, Cameroon
| | - A Talipouo
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - L Djamouko-Djonkam
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.,Faculty of Sciences, University of Dschang Cameroon, P.O. Box 67, Dschang, Cameroon
| | - H P Awono-Ambene
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
| | - C S Wondji
- Vector Group Liverpool School of Tropical Medicine Pembroke Place, Liverpool, L3 5QA, UK
| | - F Njiokou
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - C Antonio-Nkondjio
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun. .,Vector Group Liverpool School of Tropical Medicine Pembroke Place, Liverpool, L3 5QA, UK.
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11
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Hamid-Adiamoh M, Nwakanma D, Assogba BS, Ndiath MO, D’Alessandro U, Afrane YA, Amambua-Ngwa A. Influence of insecticide resistance on the biting and resting preferences of malaria vectors in the Gambia. PLoS One 2021; 16:e0241023. [PMID: 34166376 PMCID: PMC8224845 DOI: 10.1371/journal.pone.0241023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 06/11/2021] [Indexed: 11/23/2022] Open
Abstract
Background The scale-up of indoor residual spraying and long-lasting insecticidal nets, together with other interventions have considerably reduced the malaria burden in The Gambia. This study examined the biting and resting preferences of the local insecticide-resistant vector populations few years following scale-up of anti-vector interventions. Method Indoor and outdoor-resting Anopheles gambiae mosquitoes were collected between July and October 2019 from ten villages in five regions in The Gambia using pyrethrum spray collection (indoor) and prokopack aspirator from pit traps (outdoor). Polymerase chain reaction assays were performed to identify molecular species, insecticide resistance mutations, Plasmodium infection rate and host blood meal. Results A total of 844 mosquitoes were collected both indoors (421, 49.9%) and outdoors (423, 50.1%). Four main vector species were identified, including An. arabiensis (indoor: 15%, outdoor: 26%); An. coluzzii (indoor: 19%, outdoor: 6%), An. gambiae s.s. (indoor: 11%, outdoor: 16%), An. melas (indoor: 2%, outdoor: 0.1%) and hybrids of An. coluzzii-An. gambiae s.s (indoors: 3%, outdoors: 2%). A significant preference for outdoor resting was observed in An. arabiensis (Pearson X2 = 22.7, df = 4, P<0.001) and for indoor resting in An. coluzzii (Pearson X2 = 55.0, df = 4, P<0.001). Prevalence of the voltage-gated sodium channel (Vgsc)-1014S was significantly higher in the indoor-resting (allele freq. = 0.96, 95%CI: 0.78–1, P = 0.03) than outdoor-resting (allele freq. = 0.82, 95%CI: 0.76–0.87) An. arabiensis population. For An. coluzzii, the prevalence of most mutation markers was higher in the outdoor (allele freq. = 0.92, 95%CI: 0.81–0.98) than indoor-resting (allele freq. = 0.78, 95%CI: 0.56–0.86) mosquitoes. However, in An. gambiae s.s., the prevalence of Vgsc-1014F, Vgsc-1575Y and GSTe2-114T was high (allele freq. = 0.96–1), but did not vary by resting location. The overall sporozoite positivity rate was 1.3% (95% CI: 0.5–2%) in mosquito populations. Indoor-resting An. coluzzii had mainly fed on human blood while indoor-resting An. arabiensis fed on animal blood. Conclusion In this study, high levels of resistance mutations were observed that could be influencing the mosquito populations to rest indoors or outdoors. The prevalent animal-biting behaviour demonstrated in the mosquito populations suggest that larval source management could be an intervention to complement vector control in this setting.
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Affiliation(s)
- Majidah Hamid-Adiamoh
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell and Molecular, University of Ghana, Legon, Accra, Ghana
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
- * E-mail:
| | - Davis Nwakanma
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Benoit Sessinou Assogba
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Mamadou Ousmane Ndiath
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Umberto D’Alessandro
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Yaw A. Afrane
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell and Molecular, University of Ghana, Legon, Accra, Ghana
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Accra, Ghana
| | - Alfred Amambua-Ngwa
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
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12
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Ant T, Foley E, Tytheridge S, Johnston C, Goncalves A, Ceesay S, Ndiath MO, Affara M, Martinez J, Pretorius E, Grundy C, Rodrigues A, Djata P, d'Alessandro U, Bailey R, Mabey D, Last A, Logan JG. A survey of Anopheles species composition and insecticide resistance on the island of Bubaque, Bijagos Archipelago, Guinea-Bissau. Malar J 2020; 19:27. [PMID: 31941507 PMCID: PMC6964033 DOI: 10.1186/s12936-020-3115-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 01/10/2020] [Indexed: 11/10/2022] Open
Abstract
Background Bubaque is the most populous island of the Bijagos archipelago, a group of malaria-endemic islands situated off the coast of Guinea-Bissau, West Africa. Malaria vector control on Bubaque relies almost exclusively on the use of long-lasting insecticidal nets (LLINs). However, there is little information on local vector bionomics and insecticide resistance. Methods A survey of mosquito species composition was performed at the onset of the wet season (June/July) and the beginning of the dry season (November/December). Sampling was performed using indoor adult light-traps and larval dipping. Anopheles mosquitoes were identified to species level and assessed for kdr allele frequency by TaqMan PCR. Females were analysed for sporozoite positivity by CSP-ELISA. Resistance to permethrin and α-cypermethrin was measured using the CDC-bottle bioassay incorporating the synergist piperonyl-butoxide. Results Several Anopheles species were found on the island, all belonging to the Anopheles gambiae sensu lato (s.l.) complex, including An. gambiae sensu stricto, Anopheles coluzzii, Anopheles melas, and An. gambiae/An. coluzzii hybrids. Endophagic Anopheles species composition and abundance showed strong seasonal variation, with a majority of An. gambiae (50% of adults collected) caught in June/July, while An. melas was dominant in November/December (83.9% of adults collected). Anopheles gambiae had the highest sporozoite rate in both seasons, with infection rates of 13.9% and 20% in June/July and November/December, respectively. Moderate frequencies of the West African kdr allele were found in An. gambiae (36%), An. coluzzii (35%), An. gambiae/An. coluzzii hybrids (42%). Bioassays suggest moderate resistance to α-cypermethrin, but full susceptibility to permethrin. Conclusions The island of Bubaque maintained an An. gambiae s.l. population in both June/July and November/December. Anopheles gambiae was the primary vector at the onset of the wet season, while An. melas is likely to be responsible for most dry season transmission. There was moderate kdr allele frequency and synergist assays suggest likely metabolic resistance, which could reduce the efficacy of LLINs. Future control of malaria on the islands should consider the seasonal shift in mosquito species, and should employ continuous monitoring for insecticide resistance.
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Affiliation(s)
- Thomas Ant
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Erin Foley
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Scott Tytheridge
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Colin Johnston
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Adriana Goncalves
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Sainey Ceesay
- Disease Control & Elimination Theme, Medical Research Council Unit, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Mamadou Ousmane Ndiath
- Disease Control & Elimination Theme, Medical Research Council Unit, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Muna Affara
- Disease Control & Elimination Theme, Medical Research Council Unit, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Julien Martinez
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Elizabeth Pretorius
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Chris Grundy
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | | | - Paulo Djata
- Ministério da saude chez Ministério da saude de Guinea-Bissau, Bissau, Guinea-Bissau
| | - Umberto d'Alessandro
- MRC The Gambia at the London School of Hygiene & Tropical Medicine, Fajara, Gambia
| | - Robin Bailey
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - David Mabey
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Anna Last
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - James G Logan
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. .,ARCTEC, Chariot Innovations Ltd, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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