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Tia JPB, Tchicaya ESF, Zahouli JZB, Ouattara AF, Vavassori L, Assamoi JB, Small G, Koudou BG. Combined use of long-lasting insecticidal nets and Bacillus thuringiensis israelensis larviciding, a promising integrated approach against malaria transmission in northern Côte d'Ivoire. Malar J 2024; 23:168. [PMID: 38812003 PMCID: PMC11137964 DOI: 10.1186/s12936-024-04953-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 04/15/2024] [Indexed: 05/31/2024] Open
Abstract
BACKGROUND The recent reduction in malaria burden in Côte d'Ivoire is largely attributable to the use of long-lasting insecticidal nets (LLINs). However, this progress is threatened by insecticide resistance and behavioral changes in Anopheles gambiae sensu lato (s.l.) populations and residual malaria transmission, and complementary tools are required. Thus, this study aimed to assess the efficacy of the combined use of LLINs and Bacillus thuringiensis israelensis (Bti), in comparison with LLINs. METHODS This study was conducted in the health district of Korhogo, northern Côte d'Ivoire, within two study arms (LLIN + Bti arm and LLIN-only arm) from March 2019 to February 2020. In the LLIN + Bti arm, Anopheles larval habitats were treated every fortnight with Bti in addition to the use of LLINs. Mosquito larvae and adults were sampled and identified morphologically to genus and species using standard methods. The members of the An. gambiae complex were determined using a polymerase chain reaction technique. Plasmodium infection in An. gambiae s.l. and malaria incidence in local people was also assessed. RESULTS Overall, Anopheles spp. larval density was lower in the LLIN + Bti arm 0.61 [95% CI 0.41-0.81] larva/dip (l/dip) compared with the LLIN-only arm 3.97 [95% CI 3.56-4.38] l/dip (RR = 6.50; 95% CI 5.81-7.29; P < 0.001). The overall biting rate of An. gambiae s.l. was 0.59 [95% CI 0.43-0.75] biting/person/night in the LLIN + Bti arm against 2.97 [95% CI 2.02-3.93] biting/person/night in LLIN-only arm (P < 0.001). Anopheles gambiae s.l. was predominantly identified as An. gambiae sensu stricto (s.s.) (95.1%, n = 293), followed by Anopheles coluzzii (4.9%; n = 15). The human-blood index was 80.5% (n = 389) in study area. EIR was 1.36 infected bites/person/year (ib/p/y) in the LLIN + Bti arm against 47.71 ib/p/y in the LLIN-only arm. Malaria incidence dramatically declined from 291.8‰ (n = 765) to 111.4‰ (n = 292) in LLIN + Bti arm (P < 0.001). CONCLUSIONS The combined use of LLINs with Bti significantly reduced the incidence of malaria. The LLINs and Bti duo could be a promising integrated approach for effective vector control of An. gambiae for elimination of malaria.
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Affiliation(s)
- Jean-Philippe B Tia
- Université Nangui Abrogoua, Abidjan, Côte d'Ivoire.
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire.
| | - Emile S F Tchicaya
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire
- Université Péléforo Gon Coulibaly, Korhogo, Côte d'Ivoire
| | - Julien Z B Zahouli
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire
- Centre d'Entomologie Médicale et Vétérinaire, Université Alassane Ouattara, Bouaké, Côte d'Ivoire
| | - Allassane F Ouattara
- Université Nangui Abrogoua, Abidjan, Côte d'Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire
| | - Laura Vavassori
- University of Basel, Basel, Switzerland
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
| | | | - Graham Small
- Innovative Vector Control Consortium, Pembroke Place, Liverpool, L3 5QA, UK
| | - Benjamin G Koudou
- Université Nangui Abrogoua, Abidjan, Côte d'Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire
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Longo-Pendy NM, Sevidzem SL, Makanga BK, Ndotit-Manguiengha S, Boussougou-Sambe ST, Obame Ondo Kutomy P, Obame-Nkoghe J, Nkoghe-Nkoghe LC, Ngossanga B, Mvoubou FK, Koumba CRZ, Adegnika AA, Razack AS, Mavoungou JF, Mintsa-Nguema R. Assessment of environmental and spatial factors influencing the establishment of Anopheles gambiae larval habitats in the malaria endemic province of Woleu-Ntem, northern Gabon. Malar J 2024; 23:158. [PMID: 38773512 PMCID: PMC11106858 DOI: 10.1186/s12936-024-04980-5] [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: 01/02/2024] [Accepted: 05/10/2024] [Indexed: 05/23/2024] Open
Abstract
BACKGROUND This study aimed to assess the spatial distribution of Anopheles mosquito larval habitats and the environmental factors associated with them, as a prerequisite for the implementation of larviciding. METHODS The study was conducted in December 2021, during the transition period between the end of the short rainy season (September-November) and the short dry season (December-February). Physical, biological, and land cover data were integrated with entomological observations to collect Anopheles larvae in three major towns: Mitzic, Oyem, and Bitam, using the "dipping" method during the transition from rainy to dry season. The collected larvae were then reared in a field laboratory established for the study period. After the Anopheles mosquitoes had emerged, their species were identified using appropriate morphological taxonomic keys. To determine the influence of environmental factors on the breeding of Anopheles mosquitoes, multiple-factor analysis (MFA) and a binomial generalized linear model were used. RESULTS According to the study, only 33.1% out of the 284 larval habitats examined were found to be positive for Anopheles larvae, which were primarily identified as belonging to the Anopheles gambiae complex. The findings of the research suggested that the presence of An. gambiae complex larvae in larval habitats was associated with various significant factors such as higher urbanization, the size and type of the larval habitats (pools and puddles), co-occurrence with Culex and Aedes larvae, hot spots in ambient temperature, moderate rainfall, and land use patterns. CONCLUSIONS The results of this research mark the initiation of a focused vector control plan that aims to eradicate or lessen the larval habitats of An. gambiae mosquitoes in Gabon's Woleu Ntem province. This approach deals with the root causes of malaria transmission through larvae and is consistent with the World Health Organization's (WHO) worldwide objective to decrease malaria prevalence in regions where it is endemic.
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Affiliation(s)
- Neil-Michel Longo-Pendy
- Unité de Recherche en Ecologie de la Santé (URES), Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon.
| | - Silas Lendzele Sevidzem
- Laboratoire d'Ecologie des Maladies Transmissibles (LEMAT), Université Libreville Nord (ULN), Libreville, Gabon
| | | | - Saturnin Ndotit-Manguiengha
- Institut de Recherche en Écologie Tropicale (IRET), Libreville, Gabon
- Agence Gabonaise d'Etudes et d'Observations Spatiales (AGEOS), Libreville, Gabon
| | | | - Piazzy Obame Ondo Kutomy
- Programme National de Lutte Contre Le Paludisme (PNLP), Libreville, Gabon
- Universite Cheikh Anta Diop de Dakar (UCAD), Dakar, Sénégal
| | - Judicaël Obame-Nkoghe
- Unité de Recherche en Ecologie de la Santé (URES), Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
- Université des Sciences et Techniques de Masuku (USTM), Franceville, Gabon
- Department of Zoology and Entomology, Faculty of Natural and Agricultural Sciences, University of the Free State, Phuthaditjhaba, Republic of South Africa
| | - Lynda-Chancelya Nkoghe-Nkoghe
- Unité de Recherche en Ecologie de la Santé (URES), Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville, Gabon
| | | | | | | | - Ayôla Akim Adegnika
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- Institut Für Tropenmedizin, Eberhard Karls Universität, Tübingen, Germany
- Fondation Pour la Recherche Scientifique (FORS), P.O. Box 88, Cotonou, Benin
- German Center for Infection Research (DZIF), Partner site Tübingen, Tübingen, Germany
| | | | | | - Rodrigue Mintsa-Nguema
- Laboratoire d'Ecologie des Maladies Transmissibles (LEMAT), Université Libreville Nord (ULN), Libreville, Gabon
- Institut de Recherche en Écologie Tropicale (IRET), Libreville, Gabon
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Miranda LS, Rudd SR, Mena O, Hudspeth PE, Barboza-Corona JE, Park HW, Bideshi DK. The Perpetual Vector Mosquito Threat and Its Eco-Friendly Nemeses. BIOLOGY 2024; 13:182. [PMID: 38534451 DOI: 10.3390/biology13030182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 03/28/2024]
Abstract
Mosquitoes are the most notorious arthropod vectors of viral and parasitic diseases for which approximately half the world's population, ~4,000,000,000, is at risk. Integrated pest management programs (IPMPs) have achieved some success in mitigating the regional transmission and persistence of these diseases. However, as many vector-borne diseases remain pervasive, it is obvious that IPMP successes have not been absolute in eradicating the threat imposed by mosquitoes. Moreover, the expanding mosquito geographic ranges caused by factors related to climate change and globalization (travel, trade, and migration), and the evolution of resistance to synthetic pesticides, present ongoing challenges to reducing or eliminating the local and global burden of these diseases, especially in economically and medically disadvantaged societies. Abatement strategies include the control of vector populations with synthetic pesticides and eco-friendly technologies. These "green" technologies include SIT, IIT, RIDL, CRISPR/Cas9 gene drive, and biological control that specifically targets the aquatic larval stages of mosquitoes. Regarding the latter, the most effective continues to be the widespread use of Lysinibacillus sphaericus (Ls) and Bacillus thuringiensis subsp. israelensis (Bti). Here, we present a review of the health issues elicited by vector mosquitoes, control strategies, and lastly, focus on the biology of Ls and Bti, with an emphasis on the latter, to which no resistance has been observed in the field.
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Affiliation(s)
- Leticia Silva Miranda
- Graduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
| | - Sarah Renee Rudd
- Graduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
- Integrated Biomedical Graduate Studies, and School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
| | - Oscar Mena
- Undergraduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
| | - Piper Eden Hudspeth
- Undergraduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
| | - José E Barboza-Corona
- Departmento de Alimentos, Posgrado en Biociencias, Universidad de Guanajuato Campus Irapuato-Salamanca, Irapuato 36500, Guanajuato, Mexico
| | - Hyun-Woo Park
- Graduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
- Undergraduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
| | - Dennis Ken Bideshi
- Graduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
- Undergraduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
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Ragavendran K, Selvakumaran J, Muthukanagavel M, Alharbi NS, Thiruvengadam M, Mutheeswaran S, Ignacimuthu S, Ganesan P. Chemical composition and mosquitocidal properties of essential oil from Indian indigenous plants Ocimum tenuiflorum L. and Ocimum americanum L. against three vector mosquitoes. Exp Parasitol 2024; 258:108709. [PMID: 38301765 DOI: 10.1016/j.exppara.2024.108709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/27/2024] [Accepted: 01/29/2024] [Indexed: 02/03/2024]
Abstract
Mosquitoes stand out as the most perilous and impactful vectors on a global scale, transmitting a multitude of infectious diseases to both humans and other animals. The primary objective of the current research was to assess the effectiveness of EOs from Ocimum tenuiflorum L. and Ocimum americanum L. in controlling Anopheles stephensi Liston. Culex quinquefasciatus Say and Aedes aegypti L. mosquitoes. The larvae, pupae and eggs of the mosquitoes were exposed to four different concentrations (6.25-50 ppm). The tested EOs resulted in >99-100 % mortality at 120 h for the eggs of all examined mosquito species. It also showed robust larvicidal and pupicidal activity with LC50 and LC90 values of 17-39, 23-60 ppm and 46-220, and 73-412 ppm against Aedes, Culex and Anopheles mosquito species, respectively, at 24 h of treatment. The Suitability Index or Predator Safety Factor demonstrated that the EOs extracted from O. tenuiflorum L. and O. americanum L. did not cause harm to P. reticulata, D. indicus (water bug), G. affinis and nymph (dragonfly). GC-MS analysis identified the major probable constituents of the oil, including Phenol, 2-Methoxy-4-(1-Propenyl)- (28.29 %); 1-Methyl-3-(1'-Methylcyclopropyl) Cyclopentene (46.46 %); (E,E,E)-3,7,11,15-Tetramethylhexadeca-1,3,6,10,14-Pentaene (18.91 %) and 1,3-Isobenzofurandione, 3a,4,7,7a-Tetrahydro-4,7-Dimethyl (33.02 %). These constituents may play a significant role in the mosquitocidal activity of the oil. The same results were identified in the formulation prepared from the EOs. This marks the first report confirming the successful utilization of EOs derived from O. tenuiflorum L. and O. americanum L. in mosquito population control initiatives.
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Affiliation(s)
- Kamaraj Ragavendran
- Interdisciplinary Research Centre in Biology, Xavier Research Foundation, St Xavier's College (Manonmaniam Sundaranar University), Palayamkottai, Tirunelveli, Tamil Nadu, India
| | - Jeyaraj Selvakumaran
- Interdisciplinary Research Centre in Biology, Xavier Research Foundation, St Xavier's College (Manonmaniam Sundaranar University), Palayamkottai, Tirunelveli, Tamil Nadu, India
| | - Mariappan Muthukanagavel
- Interdisciplinary Research Centre in Biology, Xavier Research Foundation, St Xavier's College (Manonmaniam Sundaranar University), Palayamkottai, Tirunelveli, Tamil Nadu, India
| | - Naiyf S Alharbi
- Department of Botany and Microbiology, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Muthu Thiruvengadam
- Department of Crop Science, College of Sanghuh Life Sciences, Konkuk University, Seoul, 05029, South Korea
| | - Subramanian Mutheeswaran
- Interdisciplinary Research Centre in Biology, Xavier Research Foundation, St Xavier's College (Manonmaniam Sundaranar University), Palayamkottai, Tirunelveli, Tamil Nadu, India.
| | - Savarimuthu Ignacimuthu
- Interdisciplinary Research Centre in Biology, Xavier Research Foundation, St Xavier's College (Manonmaniam Sundaranar University), Palayamkottai, Tirunelveli, Tamil Nadu, India; The Anna and Donald Waite Chair, Creighton University, Omaha, USA
| | - Pathalam Ganesan
- Interdisciplinary Research Centre in Biology, Xavier Research Foundation, St Xavier's College (Manonmaniam Sundaranar University), Palayamkottai, Tirunelveli, Tamil Nadu, India.
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Davis EL, Hollingsworth TD, Keeling MJ. An analytically tractable, age-structured model of the impact of vector control on mosquito-transmitted infections. PLoS Comput Biol 2024; 20:e1011440. [PMID: 38484022 DOI: 10.1371/journal.pcbi.1011440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 03/26/2024] [Accepted: 02/09/2024] [Indexed: 03/27/2024] Open
Abstract
Vector control is a vital tool utilised by malaria control and elimination programmes worldwide, and as such it is important that we can accurately quantify the expected public health impact of these methods. There are very few previous models that consider vector-control-induced changes in the age-structure of the vector population and the resulting impact on transmission. We analytically derive the steady-state solution of a novel age-structured deterministic compartmental model describing the mosquito feeding cycle, with mosquito age represented discretely by parity-the number of cycles (or successful bloodmeals) completed. Our key model output comprises an explicit, analytically tractable solution that can be used to directly quantify key transmission statistics, such as the effective reproductive ratio under control, Rc, and investigate the age-structured impact of vector control. Application of this model reinforces current knowledge that adult-acting interventions, such as indoor residual spraying of insecticides (IRS) or long-lasting insecticidal nets (LLINs), can be highly effective at reducing transmission, due to the dual effects of repelling and killing mosquitoes. We also demonstrate how larval measures can be implemented in addition to adult-acting measures to reduce Rc and mitigate the impact of waning insecticidal efficacy, as well as how mid-ranges of LLIN coverage are likely to experience the largest effect of reduced net integrity on transmission. We conclude that whilst well-maintained adult-acting vector control measures are substantially more effective than larval-based interventions, incorporating larval control in existing LLIN or IRS programmes could substantially reduce transmission and help mitigate any waning effects of adult-acting measures.
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Affiliation(s)
- Emma L Davis
- Mathematics Institute, University of Warwick, Coventry, United Kingdom
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology, University of Warwick, Coventry, United Kingdom
| | | | - Matt J Keeling
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology, University of Warwick, Coventry, United Kingdom
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Sanei-Dehkordi A, Heiran R, Montaseri Z, Elahi N, Abbasi Z, Osanloo M. Promising Larvicidal Effects of Nanoliposomes Containing Carvone and Mentha spicata and Tanacetum balsamita Essential Oils Against Anopheles stephensi. Acta Parasitol 2024; 69:216-226. [PMID: 37979013 DOI: 10.1007/s11686-023-00735-5] [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: 12/22/2022] [Accepted: 10/26/2023] [Indexed: 11/19/2023]
Abstract
PURPOSE The use of synthetic pesticides to control the spread of mosquito-borne diseases has caused environmental pollution and insecticide resistance in mosquitoes. Developments of new green insecticides have thus received more attention to overcome these problems. METHODS Nanoliposomes containing carvone and essential oils were first prepared. The nanoliposome physicochemical characteristics (particle size, morphology, and successful loading) were then evaluated by Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), and the Attenuated Total Reflection-Fourier Transform InfraRed (ATR-FTIR) analyses. Larvicidal effects of carvone, Mentha spicata, and Tanacetum balsamita essential oils were investigated against the main malaria vector, Anopheles stephensi, in non-formulated and nanoformulated states. RESULTS The larvicidal effects of nanoformulated states were significantly more potent (7.2 folds, 3.5 folds, and 8 folds) than non-formulated states. Nanoliposomes containing M. spicata and T. balsamita essential oils with particle sizes of 175 ± 8 and 184 ± 5 nm showed the best efficacies (LC50 values = 9.74 and 9.36 μg/mL). CONCLUSION The prepared samples could be used as new green potent larvicides against An stephensi mosquito in further field trials. It is also recommended to investigate their efficacies against other mosquitoes.
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Affiliation(s)
- Alireza Sanei-Dehkordi
- Department of Biology and Control of Disease Vectors, School of Health, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
- Infectious and Tropical Diseases Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Roghayeh Heiran
- Estahban Higher Education Center- Shiraz University, Estahban, Iran
| | - Zahra Montaseri
- Department of Infectious Diseases, School of Medicine, Fasa University of Medical Sciences, Fasa, Iran
| | - Narges Elahi
- Department of Tissue Engineering, School of Advanced Technologies in Medicine, Fasa University of Medical Sciences, Fasa, Iran
| | - Zahra Abbasi
- Student Research Committee, Fasa University of Medical Sciences, Fasa, Iran
| | - Mahmoud Osanloo
- Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Fasa University of Medical Sciences, Fasa, Iran.
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Nkahe DL, Sonhafouo-Chiana N, Ndjeunia Mbiakop P, Kekeunou S, Mimpfoundi R, Awono-Ambene P, Wondji CS, Antonio-Nkondjio C. Can the use of larviciding with biological compounds contribute in increasing Anopheles gambiae s.l. susceptibility to pyrethroid in a population expressing high resistance intensity? PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 195:105569. [PMID: 37666599 DOI: 10.1016/j.pestbp.2023.105569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/05/2023] [Indexed: 09/06/2023]
Abstract
BACKGROUND Larviciding using non-insecticide compounds is considered appropriate for controlling outdoor biting mosquitoes and for managing insecticide resistance. However, there is still not enough information on the influence of larviciding in managing pyrethroid resistance. In the present study, we checked whether the introduction of larviciding using the biolarvicide VectoMax G in the city of Yaoundé is contributing in restoring the susceptibility of An. coluzzii populations to pyrethroids. METHODOLOGY The susceptibility status of field An. coluzzii population was evaluated at different time points before and during larviciding treatments. In addition, An. coluzzii larvae collected in the city of Yaoundé, were split into four groups and exposed to different selection regimes for many generations as follow; (i): deltamethrin 0.05%_only, (ii): Vectomax_only, (iii): Vectomax+deltamethrin 0.05%, (iv): VectoMax+deltamethrin 0.05% + susceptible. Life traits parameters were measured in the progeny and compared between colonies. The control was the susceptible laboratory strain "Ngousso". Kdr allele frequency and the profile of expression of different detoxification genes and oxidative stress genes was checked using qPCR analysis. Gene's expression was compared between the first and the last generation of each colony and in field populations collected before and during larviciding. RESULTS An increase in mosquito susceptibility to deltamethrin and permethrin was recorded for the field populations after larviciding implementation. Resistance intensity to deltamethrin was found to decrease from high to low in field populations. Only the colony vectomax+deltamethrin+susceptible presented a high susceptibility to deltamethrin after 21 generations. The kdr gene frequency was found to be unchanged in the field population and laboratory colonies. A significant decrease in the overexpression profile of Gste2 was detected in field population after larviciding implementation. Other genes showing a similar pattern though not significant were Cyp6z1, Cyp6p1 and Cyp6g16. Concerning fitness only the colony vectomax+deltamethrin+susceptible was found to display a fitness profile similar to the susceptible colony with high fecundity, high hatching rate, short development time and long adult survival rate. CONCLUSION The profile of the field population supported reversal of phenotypic resistance to pyrethroids however no reduction in the frequency of the kdr allele was recorded. Some detoxification genes were detected less overexpressed. The study suggest that reversal may take longer to achieve in a population expressing a very high resistance profile and under continuous insecticide selection pressure.
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Affiliation(s)
- Diane Leslie Nkahe
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon; Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Nadege 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, Cameroon; Faculty of Science, University of Buea, Buea, P.O. Box 63, Cameroon
| | - Paulette Ndjeunia Mbiakop
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon; Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Sévilor Kekeunou
- Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Rémy Mimpfoundi
- Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Parfait 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, Cameroon
| | - Charles Sinclair Wondji
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13591, Yaoundé, Cameroon; Vector Biology Liverpool School of Tropical medicine Pembroke Place, Liverpool L3 5QA, UK.
| | - Christophe 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, Cameroon; Faculty of Medicine Paris-Sud, 63 rue Gabriel Peri, 94276, Le Kremlin-Bicêtre, Paris, France..
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Menezes HSG, Costa-Latgé SG, Genta FA, Napoleão TH, Paiva PMG, Romão TP, Silva-Filha MHNL. A Culex quinquefasciatus strain resistant to the binary toxin from Lysinibacillus sphaericus displays altered enzyme activities and energy reserves. Parasit Vectors 2023; 16:273. [PMID: 37559134 PMCID: PMC10413512 DOI: 10.1186/s13071-023-05893-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 07/20/2023] [Indexed: 08/11/2023] Open
Abstract
BACKGROUND The resistance of a Culex quinquefasciatus strain to the binary (Bin) larvicidal toxin from Lysinibacillus sphaericus is due to the lack of expression of the toxin's receptors, the membrane-bound Cqm1 α-glucosidases. A previous transcriptomic profile of the resistant larvae showed differentially expressed genes coding Cqm1, lipases, proteases and other genes involved in lipid and carbohydrate metabolism. This study aimed to investigate the metabolic features of Bin-resistant individuals by comparing the activity of some enzymes, energy reserves, fertility and fecundity to a susceptible strain. METHODS The activity of specific enzymes was recorded in midgut samples from resistant and susceptible larvae. The amount of lipids and reducing sugars was determined for larvae and adults from both strains. Additionally, the fecundity and fertility parameters of these strains under control and stress conditions were examined. RESULTS Enzyme assays showed that the esterase activities in the midgut of resistant larvae were significantly lower than susceptible ones using acetyl-, butyryl- and heptanoyl-methylumbelliferyl esthers as substrates. The α-glucosidase activity was also reduced in resistant larvae using sucrose and a synthetic substrate. No difference in protease activities as trypsins, chymotrypsins and aminopeptidases was detected between resistant and susceptible larvae. In larval and adult stages, the resistant strain showed an altered profile of energy reserves characterized by significantly reduced levels of lipids and a greater amount of reducing sugars. The fertility and fecundity of females were similar for both strains, indicating that those changes in energy reserves did not affect these reproductive parameters. CONCLUSIONS Our dataset showed that Bin-resistant insects display differential metabolic features co-selected with the phenotype of resistance that can potentially have effects on mosquito fitness, in particular, due to the reduced lipid accumulation.
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Affiliation(s)
- Heverly Suzany G Menezes
- Department of Entomology, Instituto Aggeu Magalhães-FIOCRUZ, Av. Moraes Rego s/n, Recife, PE, 50740-465, Brazil
| | - Samara G Costa-Latgé
- Laboratory of Insect Biochemistry and Physiology, Instituto Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, RJ, 21045-900, Brazil
| | - Fernando A Genta
- Laboratory of Insect Biochemistry and Physiology, Instituto Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, RJ, 21045-900, Brazil
- National Institute for Molecular Entomology, Rio de Janeiro, RJ, 21941-902, Brazil
| | - Thiago H Napoleão
- Department of Biochemistry, Universidade Federal de Pernambuco, Recife, PE, 50670-901, Brazil
| | - Patrícia M G Paiva
- Department of Biochemistry, Universidade Federal de Pernambuco, Recife, PE, 50670-901, Brazil
| | - Tatiany P Romão
- Department of Entomology, Instituto Aggeu Magalhães-FIOCRUZ, Av. Moraes Rego s/n, Recife, PE, 50740-465, Brazil
| | - Maria Helena N L Silva-Filha
- Department of Entomology, Instituto Aggeu Magalhães-FIOCRUZ, Av. Moraes Rego s/n, Recife, PE, 50740-465, Brazil.
- National Institute for Molecular Entomology, Rio de Janeiro, RJ, 21941-902, Brazil.
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9
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Mahenge HH, Muyaga LL, Nkya JD, Kifungo KS, Kahamba NF, Ngowo HS, Kaindoa EW. Common predators and factors influencing their abundance in Anopheles funestus aquatic habitats in rural south-eastern Tanzania. PLoS One 2023; 18:e0287655. [PMID: 37363899 DOI: 10.1371/journal.pone.0287655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 06/10/2023] [Indexed: 06/28/2023] Open
Abstract
BACKGROUND The role of larval predators in regulating the Anopheles funestus population in various malaria-endemic countries remains relatively unknown. This study aimed to investigate the common predators that co-exist with Anopheles funestus group larvae and evaluate factors that influence their abundance in rural south-eastern Tanzania. METHODS Mosquito larvae and predators were sampled concurrently using standard dipper (350 ml) or 10 L bucket in previously identified aquatic habitats in selected villages in southern Tanzania. Predators and mosquito larvae were identified using standard identification keys. All positive habitats were geo-located and their physical features characterized. Water physicochemical parameters such as dissolved oxygen (DO), pH, electrical conductivity (EC), total dissolved solids (TDS) and temperature were also recorded. RESULTS A total of 85 previously identified An. funestus aquatic habitats in nine villages were sampled for larvae and potential predators. A total of 8,295 predators were sampled. Of these Coenagrionidae 57.7% (n = 4785), Corixidae 12.8% (n = 1,060), Notonectidae 9.9% (n = 822), Aeshnidae 4.9% (n = 405), Amphibian 4.5% (n = 370), Dytiscidae 3.8% (n = 313) were common. A total of 5,260 mosquito larvae were sampled, whereby Anopheles funestus group were 60.3% (n = 3,170), Culex spp. 24.3% (n = 1,279), An. gambie s.l. 8.3% (n = 438) and other anophelines 7.1% (n = 373). Permanent and aquatic habitats larger than 100m2 were positively associated with An. funestus group larvae (P<0.05) and predator abundance (P<0.05). Habitats with submerged vegetation were negatively associated with An. funestus group larvae (P<0.05). Only dissolved oxygen (DO) was positively and significantly affect the abundance of An. funestus group larvae (P<0.05). While predators' abundance was not impacted by all physicochemical parameters. CONCLUSION Six potential predator families were common in aquatic habitats of An. funestus group larvae. Additional studies are needed to demonstrate the efficacy of different predators on larval density and adult fitness traits. Interventions leveraging the interaction between mosquitoes and predators can be established to disrupt the transmission potential and survival of the An. funestus mosquitoes.
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Affiliation(s)
- Herieth H Mahenge
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- The Nelson Mandela, African Institution of Science and Technology, School of Life Sciences and Bio Engineering, Tengeru, Arusha, United Republic of Tanzania
| | - Letus L Muyaga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Joel D Nkya
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Khamis S Kifungo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Najat F Kahamba
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Biodervisty, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Biodervisty, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Emmanuel W Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- The Nelson Mandela, African Institution of Science and Technology, School of Life Sciences and Bio Engineering, Tengeru, Arusha, United Republic of Tanzania
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and the Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
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10
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Rants'o TA, Koekemoer LL, van Zyl RL. Bioactivity of select essential oil constituents against life stages of Anopheles arabiensis (Diptera: Culicidae). Exp Parasitol 2023:108569. [PMID: 37330107 DOI: 10.1016/j.exppara.2023.108569] [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: 11/14/2022] [Revised: 06/14/2023] [Accepted: 06/14/2023] [Indexed: 06/19/2023]
Abstract
Malaria is transmitted by infected female Anopheles mosquitoes, and An. arabiensis is a main malaria vector in arid African countries. Like other anophelines, its life cycle comprises of three aquatic stages; egg, larva, and pupa, followed by a free flying adult stage. Current vector control interventions using synthetic insecticides target these stages using adulticides or less commonly, larvicides. With escalating insecticide resistance against almost all conventional insecticides, identification of agents that simultaneously act at multiple stages of Anopheles life cycle presents a cost-effective opportunity. A further cost-effective approach would be the discovery of such insecticides from natural origin. Interestingly, essential oils present as potential sources of cost-effective and eco-friendly bioinsecticides. This study aimed to identify essential oil constituents (EOCs) with potential toxic effects against multiple stages of An. arabiensis life cycle. Five EOCs were assessed for inhibition of Anopheles egg hatching and ability to kill larvae, pupae and adult mosquitoes of An. arabiensis species. One of these EOCs, namely methyleugenol, exhibited potent Anopheles egg hatchability inhibition with an IC50 value of 0.51 ± 0.03 μM compared to propoxur (IC50: 5.13 ± 0.62 μM). Structure-activity relationship study revealed that methyleugenol and propoxur share a 1,2-dimethoxybenze moiety that may be responsible for the observed egg-hatchability inhibition. On the other hand, all five EOCs exhibited potent larvicidal activity with LC50 values less than 5 μM, with four of them; cis-nerolidol, trans-nerolidol, (-)-α-bisabolol, and farnesol, also possessing potent pupicidal effects (LC50 < 5 μM). Finally, all EOCs showed only moderate lethality against adult mosquitoes. This study reports for the first time, methyleugenol, (-)-α-bisabolol and farnesol as potent bioinsecticides against early life stages of An. arabiensis. This synchronized activity against Anopheles aquatic stages shows a prospect to integrate EOCs into existing adulticide-based vector control interventions.
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Affiliation(s)
- Thankhoe A Rants'o
- Pharmacology Division, Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; WITS Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Lizette L Koekemoer
- WITS Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Robyn L van Zyl
- Pharmacology Division, Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; WITS Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
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11
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Florez D, Young AJ, Bernabé KJ, Hyman JM, Qu Z. Modeling Sustained Transmission of Wolbachia among Anopheles Mosquitoes: Implications for Malaria Control in Haiti. Trop Med Infect Dis 2023; 8:tropicalmed8030162. [PMID: 36977163 PMCID: PMC10056903 DOI: 10.3390/tropicalmed8030162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/04/2023] [Accepted: 03/06/2023] [Indexed: 03/12/2023] Open
Abstract
Wolbachia infection in Anopheles albimanus mosquitoes can render mosquitoes less capable of spreading malaria. We developed and analyzed a mechanistic compartmental ordinary differential equation model to evaluate the effectiveness of Wolbachia-based vector control strategies among wild Anopheles mosquitoes in Haiti. The model tracks the mosquito life stages, including egg, larva, and adult (male and female). It also accounts for critical biological effects, such as the maternal transmission of Wolbachia through infected females and cytoplasmic incompatibility, which effectively sterilizes uninfected females when they mate with infected males. We derive and interpret dimensionless numbers, including the basic reproductive number and next-generation numbers. The proposed system presents a backward bifurcation, which indicates a threshold infection that needs to be exceeded to establish a stable Wolbachia infection. The sensitivity analysis ranks the relative importance of the epidemiological parameters at baseline. We simulate different intervention scenarios, including prerelease mitigation using larviciding and thermal fogging before the release, multiple releases of infected populations, and different release times of the year. Our simulations show that the most efficient approach to establishing Wolbachia is to release all the infected mosquitoes immediately after the prerelease mitigation process. Moreover, the model predicts that it is more efficient to release during the dry season than the wet season.
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Affiliation(s)
- Daniela Florez
- Department of Mathematics, Tulane University, New Orleans, LA 70118, USA; (D.F.); (J.M.H.)
| | - Alyssa J. Young
- School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112, USA; (A.J.Y.); (K.J.B.)
| | - Kerlly J. Bernabé
- School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112, USA; (A.J.Y.); (K.J.B.)
| | - James M. Hyman
- Department of Mathematics, Tulane University, New Orleans, LA 70118, USA; (D.F.); (J.M.H.)
| | - Zhuolin Qu
- Department of Mathematics, University of Texas at San Antonio, San Antonio, TX 78249, USA
- Correspondence:
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12
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Teshome A, Erko B, Golassa L, Yohannes G, Irish SR, Zohdy S, Dugassa S. Laboratory-based efficacy evaluation of Bacillus thuringiensis var. israelensis and temephos larvicides against larvae of Anopheles stephensi in ethiopia. Malar J 2023; 22:48. [PMID: 36759908 PMCID: PMC9912598 DOI: 10.1186/s12936-023-04475-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 01/30/2023] [Indexed: 02/11/2023] Open
Abstract
BACKGROUND Malaria, transmitted by the bite of infective female Anopheles mosquitoes, remains a global public health problem. The presence of an invasive Anopheles stephensi, capable of transmitting Plasmodium vivax and Plasmodium falciparum parasites was first reported in Ethiopia in 2016. The ecology of An. stephensi is different from that of Anopheles arabiensis, the primary Ethiopian malaria vector, and this suggests that alternative control strategies may be necessary. Larviciding may be an effective alternative strategy, but there is limited information on the susceptibility of Ethiopian An. stephensi to common larvicides. This study aimed to evaluate the efficacy of temephos and Bacillus thuringiensis var. israelensis (Bti) larvicides against larvae of invasive An. stephensi. METHODS The diagnostic doses of two larvicides, temephos (0.25 ml/l) and Bti (0.05 mg/l) were tested in the laboratory against the immature stages (late third to early fourth stages larvae) of An. stephensi collected from the field and reared in a bio-secure insectary. Larvae were collected from two sites (Haro Adi and Awash Subuh Kilo). For each site, three hundred larvae were tested against each insecticide (as well as an untreated control), in batches of 25. The data from all replicates were pooled and descriptive statistics prepared. RESULTS The mortality of larvae exposed to temephos was 100% for both sites. Mortality to Bti was 99.7% at Awash and 100% at Haro Adi site. CONCLUSIONS Larvae of An. stephensi are susceptible to temephos and Bti larvicides suggesting that larviciding with these insecticides through vector control programmes may be effective against An. stephensi in these localities.
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Affiliation(s)
- Abebe Teshome
- National Malaria Elimination Programme, Ministry of Health Ethiopia, PO Box 1234, Addis Ababa, Ethiopia.
| | - Berhanu Erko
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
| | - Lemu Golassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
| | - Gedeon Yohannes
- Department of Zoological Sciences, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
| | - Seth R Irish
- Swiss Tropical and Public Health Institute (Swiss TPH), 4123, Allschwil, Switzerland
| | - Sarah Zohdy
- Centers for Disease Control and Prevention, US President's Malaria Initiative, Atlanta, GA, USA
| | - Sisay Dugassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
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13
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Comparative analysis of the larvicidal activity of temephos (EC50) and novaluaron (EC10) to control Anopheles stephensi in Sri Lanka. Parasitol Int 2023; 92:102686. [DOI: 10.1016/j.parint.2022.102686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 07/06/2022] [Accepted: 09/22/2022] [Indexed: 11/22/2022]
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14
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Gowelo S, Meijer P, Tizifa T, Malenga T, Mburu MM, Kabaghe AN, Terlouw DJ, van Vugt M, Phiri KS, Mzilahowa T, Koenraadt CJM, van den Berg H, Manda-Taylor L, McCann RS, Takken W. Community Participation in Habitat Management and Larviciding for the Control of Malaria Vectors in Southern Malawi. Am J Trop Med Hyg 2023; 108:51-60. [PMID: 36410320 PMCID: PMC9833073 DOI: 10.4269/ajtmh.21-1127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 08/23/2022] [Indexed: 11/23/2022] Open
Abstract
Larval source management (LSM) could reduce malaria transmission when executed alongside core vector control strategies. Involving communities in LSM could increase intervention coverage, reduce operational costs, and promote sustainability via community buy-in. We assessed the effectiveness of community-led LSM to reduce anopheline larval densities in 26 villages along the perimeter of Majete Wildlife Reserve in southern Malawi. The communities formed LSM committees which coordinated LSM activities in their villages following specialized training. Effectiveness of larviciding by LSM committees was assessed via pre- and post-spray larval sampling. The effect of community-led LSM on anopheline larval densities in intervention villages was assessed via comparisons with densities in non-LSM villages over a period of 14 months. Surveys involving 502 respondents were undertaken in intervention villages to explore community motivation and participation, and factors influencing these outcomes. Larviciding by LSM committees reduced anopheline larval densities in post-spray sampling compared with pre-spray sampling (P < 0.0001). No differences were observed between anopheline larval densities during pre-spray sampling in LSM villages and those in non-LSM villages (P = 0.282). Knowledge about vector biology and control, and someone's role in LSM motivated community participation in the vector control program. Despite reducing anopheline larval densities in LSM villages, the impact of the community-led LSM could not be detected in our study setting because of low mosquito densities after scale-up of core malaria control interventions. Still, the contributions of the intervention in increasing a community's knowledge of malaria, its risk factors, and its control methods highlight potential benefits of the approach.
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Affiliation(s)
- Steven Gowelo
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.,MAC Communicable Diseases Action Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Paola Meijer
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Tinashe Tizifa
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Tumaini Malenga
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,African Institute for Development Policy, Lilongwe, Malawi
| | - Monicah M Mburu
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.,Macha Research Trust, Choma, Zambia
| | - Alinune N Kabaghe
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Dianne J Terlouw
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Michèle van Vugt
- Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Kamija S Phiri
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Themba Mzilahowa
- MAC Communicable Diseases Action Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | | | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Lucinda Manda-Taylor
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Robert S McCann
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.,Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
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15
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Carrasco-Escobar G, Moreno M, Fornace K, Herrera-Varela M, Manrique E, Conn JE. The use of drones for mosquito surveillance and control. Parasit Vectors 2022; 15:473. [PMID: 36527116 PMCID: PMC9758801 DOI: 10.1186/s13071-022-05580-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 11/04/2022] [Indexed: 12/23/2022] Open
Abstract
In recent years, global health security has been threatened by the geographical expansion of vector-borne infectious diseases such as malaria, dengue, yellow fever, Zika and chikungunya. For a range of these vector-borne diseases, an increase in residual (exophagic) transmission together with ecological heterogeneity in everything from weather to local human migration and housing to mosquito species' behaviours presents many challenges to effective mosquito control. The novel use of drones (or uncrewed aerial vehicles) may play a major role in the success of mosquito surveillance and control programmes in the coming decades since the global landscape of mosquito-borne diseases and disease dynamics fluctuates frequently and there could be serious public health consequences if the issues of insecticide resistance and outdoor transmission are not adequately addressed. For controlling both aquatic and adult stages, for several years now remote sensing data have been used together with predictive modelling for risk, incidence and detection of transmission hot spots and landscape profiles in relation to mosquito-borne pathogens. The field of drone-based remote sensing is under continuous change due to new technology development, operation regulations and innovative applications. In this review we outline the opportunities and challenges for integrating drones into vector surveillance (i.e. identification of breeding sites or mapping micro-environmental composition) and control strategies (i.e. applying larval source management activities or deploying genetically modified agents) across the mosquito life-cycle. We present a five-step systematic environmental mapping strategy that we recommend be undertaken in locations where a drone is expected to be used, outline the key considerations for incorporating drone or other Earth Observation data into vector surveillance and provide two case studies of the advantages of using drones equipped with multispectral cameras. In conclusion, recent developments mean that drones can be effective for accurately conducting surveillance, assessing habitat suitability for larval and/or adult mosquitoes and implementing interventions. In addition, we briefly discuss the need to consider permissions, costs, safety/privacy perceptions and community acceptance for deploying drone activities.
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Affiliation(s)
- Gabriel Carrasco-Escobar
- grid.11100.310000 0001 0673 9488Health Innovation Laboratory, Institute of Tropical Medicine “Alexander Von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, Peru
- grid.266100.30000 0001 2107 4242School of Public Health, University of California San Diego, La Jolla, USA
| | - Marta Moreno
- grid.8991.90000 0004 0425 469XFaculty of Infectious and Tropical Diseases and Centre for Climate Change and Planetary Health, London School Hygiene and Tropical Medicine, London, UK
| | - Kimberly Fornace
- grid.8991.90000 0004 0425 469XFaculty of Infectious and Tropical Diseases and Centre for Climate Change and Planetary Health, London School Hygiene and Tropical Medicine, London, UK
- grid.8756.c0000 0001 2193 314XSchool of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK
- grid.4280.e0000 0001 2180 6431 Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore, Singapore
| | - Manuela Herrera-Varela
- grid.10689.360000 0001 0286 3748Grupo de Investigación en Entomología, Facultad de Medicina, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Edgar Manrique
- grid.11100.310000 0001 0673 9488Health Innovation Laboratory, Institute of Tropical Medicine “Alexander Von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jan E. Conn
- grid.238491.50000 0004 0367 6866The Wadsworth Center, New York State Department of Health, Albany, NY USA
- grid.189747.40000 0000 9554 2494Department of Biomedical Sciences, School of Public Health, State University of New York, Albany, NY USA
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16
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Ragavendran C, Balasubramani G, Tijo C, Manigandan V, Kweka EJ, Karthika P, Sivasankar P, Thomas A, Natarajan D, Nakouti I, Malafaia G. Cladophialophora bantiana metabolites are efficient in the larvicidal and ovicidal control of Aedes aegypti, and Culex quinquefasciatus and have low toxicity in zebrafish embryo. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 852:158502. [PMID: 36058332 DOI: 10.1016/j.scitotenv.2022.158502] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 06/15/2023]
Abstract
Mosquitoes' current insecticide resistance status in available public health insecticides is a serious threat to mosquito control initiatives. Microbe-based control agents provide an alternative to conventional pesticides and insecticides, as they can be more targeted than synthetic insecticides. The present study was focused on identifying and investigating the mosquitocidal potential of Cladophialophora bantiana, an endophytic fungus isolated from Opuntia ficus-indica. The Cladophialophora species was identified through phylogenetic analysis of the rDNA sequence. The isolated fungus was first evaluated for its potential to produce metabolites against Aedes aegpti and Culex quinquefasciatus larvae in the 1-4th instar. The secondary metabolites of mycelium extract were assessed at various test doses (100, 200, 300, 400, and 500 μg/mL) in independent bioassays for each instar of selected mosquito larvae. After 48 h of exposure, A. aegypti expressed LC50 values of 13.069, 18.085, 9.554, and 11.717 μg/mL and LC90 = 25.702, 30.860, 17.275, and 19.601 μg/mL; followed by C. quinquefasciatus LC50 = 14.467, 11.766, 5.934, and 7.589 μg/mL, and LC90 = 29.529, 20.767, 11.192, and 13.296 μg/mL. The mean % of ovicidal bioassay was recorded 120 h after exposure. The hatchability (%) was proportional to mycelia metabolite concentration. The enzymatic level of acetylcholinesterase in fungal mycelial metabolite treated 4th instar larvae indicated a dose-dependent pattern. The GC-MS profile of C. bantiana extracts identified five of the most abundant compounds, namely cyclobutane, trans-3-undecene-1,5-diyne, 1-bromo-2-chloro, propane, 1,2,3-trichloro-2-methyl-, 5,5,10,10-tetrachlorotricyclo, and phenol, which had the killing effect in mosquitoes. Furthermore, the C. bantiana fungus ethyl acetate extracts had a strong larvicidal action on A. aegypti and C. quinquefasciatus. Finally, the toxicity test on zebrafish embryos revealed the induction of malformations only at concentrations above 1 mg/mL. Therefore, our study pioneered evidence that C. bantiana fungal metabolites effectively control A. aegypti and C. qunquefasciastus and show less lethality in zebrafish embryos at concentrations up to 500 μg/mL.
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Affiliation(s)
- Chinnasamy Ragavendran
- Natural Drug Research Laboratory, Department of Biotechnology, School of Biosciences, Periyar University, Salem 636 011, Tamil Nadu, India; Department of Cariology, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Chennai 600 077, India.
| | - Govindasamy Balasubramani
- Department of Research and Innovation, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences (SIMATS), Chennai 602105, Tamil Nadu, India
| | - Cherian Tijo
- Department of Ocean Studies and Marine Biology, Pondicherry University, Port Blair Campus, Brookshabad, Port Blair, Andamans 744112, India
| | | | - Eliningaya J Kweka
- Division of Livestock and Human Diseases Vector Control, Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, Tanzania; Department of Medical Parasitology and Entomology, Catholic University of Health and Allied Sciences, P.O. Box 1464, Mwanza, Tanzania
| | - Pandi Karthika
- Natural Drug Research Laboratory, Department of Biotechnology, School of Biosciences, Periyar University, Salem 636 011, Tamil Nadu, India
| | - Palaniappan Sivasankar
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland
| | - Adelina Thomas
- School of Pharmacy, Catholic University of Health and Allied Sciences, P.O. Box 1464, Mwanza, Tanzania
| | - Devarajan Natarajan
- Natural Drug Research Laboratory, Department of Biotechnology, School of Biosciences, Periyar University, Salem 636 011, Tamil Nadu, India
| | - Ismini Nakouti
- Centre for Natural Products Discovery (CNPD), School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Guilherme Malafaia
- Laboratory of Toxicology Applied to the Environment, Goiano Federal Institute, Urutaí, GO, Brazil; Post-Graduation Program in Conservation of Cerrado Natural Resources, Goiano Federal Institute, Urutaí, GO, Brazil; Post-Graduation Program in Ecology, Conservation, and Biodiversity, Federal University of Uberlândia, Uberlândia, MG, Brazil; Post-Graduation Program in Biotechnology and Biodiversity, Federal University of Goiás, Goiânia, GO, Brazil.
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García GA, Fuseini G, Donfack OT, Wofford RN, Nlang JAM, Efiri PB, Maye VON, Weppelmann TA, Galick D, Phiri WP, DeBoer K, Smith JM, Eyono JNM, Rivas MR, Guerra CA, von Fricken ME. The need for larval source management accompanying urban development projects in malaria endemic areas: a case study on Bioko Island. Malar J 2022; 21:328. [PMCID: PMC9664620 DOI: 10.1186/s12936-022-04362-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 11/04/2022] [Indexed: 11/16/2022] Open
Abstract
Abstract
Background
In 2017, several new housing districts were constructed on Bioko Island, Equatorial Guinea. This case study assessed the impact construction projects had on mosquito larval habitats and the effectiveness of larval source management in reducing malaria vector density within the surrounding area.
Methods
Anopheline larval presence was assessed at 11 new construction sites by the proportion of larval habitats containing Anopheline pupae and late instar larval stages. Bacillus thuringiensis israelensis (Bti) larvicide was applied weekly to nine locations for 30 weeks, while two locations received no larvicide and acted as controls. Adult mosquito density was monitored via human landing collections in adjacent communities of six construction sites, including the two control sites.
Results
The sites that received Bti had significantly lower observation rates of both pupae (3.2% vs. 18.0%; p < 0.001) and late instar Anopheles spp. mosquitoes (14.1 vs. 43.6%; p < 0.001) compared to the two untreated sites. Anopheles spp. accounted for 67% of mosquitoes collected with human landing collections and were captured at significantly lower levels in communities adjacent to treated construction sites compared to untreated sites (p < 0.001), with an estimated 38% reduction in human biting rate (IRR: 0.62, 95% CI IRR: 0.55, 0.69). Seven months after the start of the study, untreated sites were treated due to ethical concerns given results from treatment sties, necessitating immediate Bti application. The following week, the number of habitats, the proportion of larval sites with Anopheles spp. pupae, late instars, and adult biting rates in adjacent communities to these sites all decreased to comparable levels across all sites.
Conclusion
Findings suggest larval source management represents an effective intervention to suppress mosquito populations during infrastructure development. Incorporating larval source management into ongoing and planned construction initiatives represents an opportunity to fine tune vector control in response to anthropogenetic changes. Ideally, this should become standard practice in malaria-endemic regions in order to reduce viable mosquito habitats that are common by-products of construction.
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Knowledge, practices and perceptions of communities during a malaria larviciding randomized trial in the city of Yaoundé, Cameroon. PLoS One 2022; 17:e0276500. [PMID: 36327271 PMCID: PMC9632894 DOI: 10.1371/journal.pone.0276500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/08/2022] [Indexed: 11/06/2022] Open
Abstract
Background Urban malaria is becoming a major public health concern in major cities in Cameroon. To improve malaria vector control, a pilot larviciding trial was conducted to assess its impact on mosquito density and malaria transmission intensity in Yaoundé. The present study investigated perceptions and practices of communities on malaria control during the larviciding trial implemented in Yaoundé. Methods Quantitative and qualitative data were collected in non-intervention and intervention areas. Quantitative data were collected during three cross-sectional surveys using a structured pre-tested questionnaire while qualitative data were obtained through interviews. A total of 26 in-depth interviews and eight focus group discussions with community members were performed. A binary logistic regression model was used to assess the perception of the community on larviciding impact on some malaria or bed nets use indicators. Results People living in intervention areas were 2.64 times more likely to know the mode of malaria transmission (95% CI: 1.82–3.84; p<0.001) and 1.3 time more likely to know mosquito breeding habitats (95% CI: 1.06–1.56; p = 0.009) compared to those living in non-intervention areas. In intervention areas, interviewee opinions on larviciding were generally good i.e. most interviewees reported having noticed a reduction in mosquito nuisance and malaria cases following larviciding implementation; whereas in non-intervention areas no report of reduction of mosquito nuisance was recorded. LLINs were regularly used by the population despite the implementation of larviciding treatments. There was high interest in larviciding program and demand for continuation, even if this needs the community involvement. Conclusion The larviciding program in the city of Yaoundé did not negatively affected community members’ behaviour and practices concerning the use of treated nets. The study indicated the acceptance of larviciding program by the population. This positive environment could favour the implementation of future antilarval control activities in the city of Yaoundé.
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Scolari F, Girella A, Croce AC. Imaging and spectral analysis of autofluorescence patterns in larval head structures of mosquito vectors. Eur J Histochem 2022; 66. [PMID: 36128772 PMCID: PMC9528535 DOI: 10.4081/ejh.2022.3462] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 08/03/2022] [Indexed: 11/23/2022] Open
Abstract
Autofluorescence (AF) in mosquitoes is currently poorly explored, despite its great potential as a marker of body structures and biological functions. Here, for the first time AF in larval heads of two mosquitoes of key public health importance, Aedes albopictus and Culex pipiens, is studied using fluorescence imaging and spectrofluorometry, similarly to a label-free histochemical approach. In generally conserved distribution patterns, AF shows differences between mouth brushes and antennae of the two species. The blue AF ascribable to resilin at the antennal bases, more extended in Cx. pipiens, suggests a potential need to support different antennal movements. The AF spectra larger in Cx. pipiens indicate a variability in material composition and properties likely relatable to mosquito biology, including diverse feeding and locomotion behaviours with implications for vector control.
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Affiliation(s)
- Francesca Scolari
- Institute of Molecular Genetics, Italian National Research Council (CNR), Pavia.
| | - Alessandro Girella
- Department of Chemistry - C.S.G.I., University of Pavia; Centro Interdipartimentale di Studi e Ricerche per la Conservazione del Patrimonio Culturale (CISRiC), University of Pavia.
| | - Anna Cleta Croce
- Institute of Molecular Genetics, Italian National Research Council (CNR), Pavia.
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Matindo AY, Meshi EB, Kapologwe NA, Kengia JT, Kajange S, Chaki P, Munisi DZ. Biolarviciding implementation in southern Tanzania: Scalability opportunities and challenges. PLoS One 2022; 17:e0273490. [PMID: 36026502 PMCID: PMC9417020 DOI: 10.1371/journal.pone.0273490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 08/09/2022] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The resistance to insecticides among malaria vectors poses a global challenge in the efforts towards malaria elimination. This calls for an addition of larval control methods such as biolarviciding. However, the implementation of biolarviciding in Tanzania has been very low. Therefore, this study explored factors affecting the implementation of biolarviciding in the councils of Southern Tanzania. METHODS A mixed method descriptive qualitative, cross-sectional study design was used to collect data from 32 community leaders through key informant interviews and 12 Vectors Control Coordinators through in-depth interviews and questionnaire interviews and document review of implementation reports in 12 councils. Data were analysed using ATLAS.ti version 8, where content analysis was performed and SPSS for the quantitative data. RESULTS The study found low implementation of biolarviciding intervention in 9 out of 12 (75%) surveyed councils. All Vector Control Coordinators reported a shortage of at least one type of resources: funds, trained personnel, transport, supply of biolarvicide, and equipment; low community involvement (50%) and low level of community participation 83.3% (10/12). CONCLUSION This study highlights resource inadequacy and low community participation as main barriers to the implementation of biolarviciding. Availing adequate resources and strengthening community participation through involvement in all stages of implementation is crucial for successful and sustainable implementation.
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Affiliation(s)
- Athuman Yusuph Matindo
- Department of Public Health, School of Nursing and Public Health, University of Dodoma, Dodoma, Tanzania
| | - Eugene Benjamin Meshi
- Department of Public Health, School of Nursing and Public Health, University of Dodoma, Dodoma, Tanzania
| | | | - James Tumaini Kengia
- President’s Office Regional Administration and Local Government, Dodoma, Tanzania
| | - Stella Kajange
- President’s Office Regional Administration and Local Government, Dodoma, Tanzania
| | - Prosper Chaki
- Department of Environmental Health and Ecological Sciences, Ifakara Health Institute, Dar es Salaam, Tanzania
| | - David Zadock Munisi
- Department of Microbiology and Parasitology, School of Medicine and Dentistry, University of Dodoma, Dodoma, Tanzania
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Larval mosquito management and risk to aquatic ecosystems: A comparative approach including current tactics and gene-drive Anopheles techniques. Transgenic Res 2022; 31:489-504. [PMID: 35798930 PMCID: PMC9489571 DOI: 10.1007/s11248-022-00315-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 06/13/2022] [Indexed: 11/23/2022]
Abstract
Genetic engineering of mosquitoes represents a promising tactic for reducing human suffering from malaria. Gene-drive techniques being developed that suppress or modify populations of Anopheles gambiae have the potential to be used with, or even possibly obviate, microbial and synthetic insecticides. However, these techniques are new and therefore there is attendant concern and uncertainty from regulators, policymakers, and the public about their environmental risks. Therefore, there is a need to assist decision-makers and public health stewards by assessing the risks associated with these newer mosquito management tactics so the risks can be compared as a basis for informed decision making. Previously, the effect of gene-drive mosquitoes on water quality in Africa was identified as a concern by stakeholders. Here, we use a comparative risk assessment approach for the effect of gene-drive mosquitoes on water quality in Africa. We compare the use of existing larvicides and the proposed genetic techniques in aquatic environments. Based on our analysis, we conclude that the tactic of gene-drive Anopheles for malaria management is unlikely to result in risks to aquatic environments that exceed current tactics for larval mosquitoes. As such, these new techniques would likely comply with currently recommended safety standards.
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Kahamba NF, Finda M, Ngowo HS, Msugupakulya BJ, Baldini F, Koekemoer LL, Ferguson HM, Okumu FO. Using ecological observations to improve malaria control in areas where Anopheles funestus is the dominant vector. Malar J 2022; 21:158. [PMID: 35655190 PMCID: PMC9161514 DOI: 10.1186/s12936-022-04198-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 05/19/2022] [Indexed: 11/10/2022] Open
Abstract
The most important malaria vectors in sub-Saharan Africa are Anopheles gambiae, Anopheles arabiensis, Anopheles funestus, and Anopheles coluzzii. Of these, An. funestus presently dominates in many settings in east and southern Africa. While research on this vector species has been impeded by difficulties in creating laboratory colonies, available evidence suggests it has certain ecological vulnerabilities that could be strategically exploited to greatly reduce malaria transmission in areas where it dominates. This paper examines the major life-history traits of An. funestus, its aquatic and adult ecologies, and its responsiveness to key interventions. It then outlines a plausible strategy for reducing malaria transmission by the vector and sustaining the gains over the medium to long term. To illustrate the propositions, the article uses data from south-eastern Tanzania where An. funestus mediates over 85% of malaria transmission events and is highly resistant to key public health insecticides, notably pyrethroids. Both male and female An. funestus rest indoors and the females frequently feed on humans indoors, although moderate to high degrees of zoophagy can occur in areas with large livestock populations. There are also a few reports of outdoor-biting by the species, highlighting a broader range of behavioural phenotypes that can be considered when designing new interventions to improve vector control. In comparison to other African malaria vectors, An. funestus distinctively prefers permanent and semi-permanent aquatic habitats, including river streams, ponds, swamps, and spring-fed pools. The species is therefore well-adapted to sustain its populations even during dry months and can support year-round malaria transmission. These ecological features suggest that highly effective control of An. funestus could be achieved primarily through strategic combinations of species-targeted larval source management and high quality insecticide-based methods targeting adult mosquitoes in shelters. If done consistently, such an integrated strategy has the potential to drastically reduce local populations of An. funestus and significantly reduce malaria transmission in areas where this vector species dominates. To sustain the gains, the programmes should be complemented with gradual environmental improvements such as house modification to maintain biting exposure at a bare minimum, as well as continuous engagements of the resident communities and other stakeholders.
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Affiliation(s)
- Najat F Kahamba
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, G128QQ, Glasgow, UK.
| | - Marceline Finda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- School of Public Health, Faculty of Health Science, University of the Witwatersrand, Johannesburg, South Africa
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, G128QQ, Glasgow, UK
| | - Betwel J Msugupakulya
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Francesco Baldini
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, G128QQ, Glasgow, UK
| | - Lizette L Koekemoer
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Heather M Ferguson
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, G128QQ, Glasgow, UK
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, G128QQ, Glasgow, UK.
- School of Public Health, Faculty of Health Science, University of the Witwatersrand, Johannesburg, South Africa.
- School of Life Science and Biotechnology, Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania.
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A Systematic Review and Meta-Analysis of Malaria Test Positivity Outcomes and Programme Interventions in Low Transmission Settings in Southern Africa, 2000-2021. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19116776. [PMID: 35682356 PMCID: PMC9180605 DOI: 10.3390/ijerph19116776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 04/27/2022] [Accepted: 05/04/2022] [Indexed: 02/01/2023]
Abstract
Malaria is one of the most significant causes of mortality and morbidity globally, especially in sub-Saharan Africa (SSA) countries. It harmfully disturbs the public’s health and the economic growth of many developing countries. Despite the massive effect of malaria transmission, the overall pooled proportion of malaria positivity rate in Southern Africa is still elusive. Therefore, the objective of this systematic review and meta-analysis is to pool estimates of the incidence of the malaria positivity rate, which is the first of its kind in South African countries. A literature search is performed to identify all published articles reporting the incidence of malaria positivity in Southern Africa. Out of the 3359 articles identified, 17 studies meet the inclusion for systematic review and meta-analysis. In addition, because substantial heterogeneity is expected due to the studies being extracted from the universal population, random-effects meta-analyses are carried out to pool the incidence of the malaria positivity rate from diverse diagnostic methods. The result reveals that between-study variability is high (τ2 = 0.003; heterogeneity I2 = 99.91% with heterogeneity chi-square χ2 = 18,143.95, degree of freedom = 16 and a p-value < 0.0001) with the overall random pooled incidence of 10% (95%CI: 8−13%, I2 = 99.91%) in the malaria positivity rate. According to the diagnostic method called pooled incidence estimate, the rapid diagnostic test (RDT) is the leading diagnostic method (17%, 95%CI: 11−24%, I2 = 99.95%), followed by RDT and qPCR and RDT and loop mediated isothermal amplification (LAMP), respectively, found to be (3%, 95%CI: 2−3%, I2 = 0%) and (2%, 95%CI: 1−3%, I2 = 97.94%).Findings of the present study suggest high malaria positive incidence in the region. This implies that malaria control and elimination programmes towards malaria elimination could be negatively impacted and cause delays in actualising malaria elimination set dates. Further studies consisting of larger samples and continuous evaluation of malaria control programmes are recommended.
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Batume C, Akol AM, Mukwaya LG, Birungi J, Kayondo JK. Life-history attributes of juvenile Anopheles gambiae s.s. in central Uganda; implications for malaria control interventions. MEDICAL AND VETERINARY ENTOMOLOGY 2022; 36:212-222. [PMID: 35388913 PMCID: PMC9322574 DOI: 10.1111/mve.12568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 02/07/2022] [Accepted: 02/11/2022] [Indexed: 06/14/2023]
Abstract
Malaria is among the leading causes of death in Uganda, and Anopheles gambiae sensu stricto (s.s.) is the predominant vector. Although current vector control interventions have greatly reduced the malaria burden, the disease persists. New interventions are needed in order to eradicate them. Evaluation of new tools will require the availability of well-characterized test vector populations. Juvenile An. gambiae s.s. from Kibbuye and Kayonjo-derived populations were characterized under semi-field and laboratory conditions, given that various vector traits, including abundance and fitness are dependent on development profiles at this life stage. Ten replicates comprising 30 first instar larvae each were profiled for various life-history attributes (egg hatching, larval development time, larval survivorship, pupal weight and pupation rate). All parameters were similar for the two sites under laboratory conditions. However, the similarities or differences between field and laboratory development were parameter-specific. Whereas, larval survivorship and pupal weight were similar across seasons and laboratory in colonies from both sites, in the semi-field settings, pupation rate and larval survivorship differed between seasons in both sites. In addition, the average larval development time during the wet season was longer than that of the laboratory for both sites. Availability of mirror field sites is important for future tool evaluations.
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Affiliation(s)
- Charles Batume
- Department of EntomologyUganda Virus Research Institute (UVRI)EntebbeUganda
| | - Anne M. Akol
- Department of Zoology, Entomology and Fisheries SciencesCollege of Natural Sciences, Makerere University KampalaKampalaUganda
| | - Louis G. Mukwaya
- Department of EntomologyUganda Virus Research Institute (UVRI)EntebbeUganda
| | - Josephine Birungi
- Department of EntomologyUganda Virus Research Institute (UVRI)EntebbeUganda
- ILRI‐ BiosciencesInternational Livestock Research InstituteNairobiKenya
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Community-Based Control of Malaria Vectors Using Bacillus thuringiensis var. Israelensis ( Bti) in Rwanda. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19116699. [PMID: 35682283 PMCID: PMC9180564 DOI: 10.3390/ijerph19116699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 05/19/2022] [Accepted: 05/25/2022] [Indexed: 01/27/2023]
Abstract
Larval source management (LSM) programs for control of malaria vectors are often vertically organized, while there is much potential for involving local communities in program implementation. To address this, we evaluated the entomological impact of community-based application of Bacillus thuringiensis var. israelensis (Bti) in a rice irrigation scheme in Ruhuha, Rwanda. A non-randomized trial with control compared a Bti implementation program that was supervised by the project team (ES) with a program that was led and carried out by local rice farming communities (CB). One other area served as a control to assess mosquito populations without Bti application. Entomological surveys were carried out every two weeks and assessed the presence and abundance of the larval, pupal, and adult stages of Anopheles mosquitoes. In ES, the per round reduction in Anopheles larval habitats was estimated at 49%. This reduction was less in CB (28%) and control (22%) although the per round reduction in CB was still significantly higher than in control. Pupal production was almost completely prevented from round 5 (out of 10) onwards in both CB (average habitat occupancy 0.43%) and ES intervention arms (average habitat occupancy 0.27%), whereas pupal occupancy rates were on average 12.8% from round 5 onwards in the control. Emergence of adult mosquitoes from rice fields was thus prevented although this was not directly noticeable in adult An. gambiae populations in houses nearby the rice fields. Together with our earlier work on the willingness to financially contribute to the LSM program and the high perceived safety and acceptance of the Bti product, the current study demonstrates that, in an environment with limited resources, communities could become more engaged in LSM program implementation and contribute directly to malaria vector control in their environment.
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Derua YA, Tungu PK, Malima RC, Mwingira V, Kimambo AG, Batengana BM, Machafuko P, Sambu EZ, Mgaya YD, Kisinza WN. Laboratory and semi-field evaluation of the efficacy of Bacillus thuringiensis var. israelensis (Bactivec®) and Bacillus sphaericus (Griselesf®) for control of mosquito vectors in northeastern Tanzania. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2022; 2:100089. [PMID: 35664894 PMCID: PMC9157456 DOI: 10.1016/j.crpvbd.2022.100089] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 04/11/2022] [Accepted: 04/27/2022] [Indexed: 10/25/2022]
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Rulisa A, van Kempen L, Mutesa L, Hakizimana E, Ingabire CM, Kateera F, Koenraadt CJM, van Vugt M, van den Borne B. Willingness to Contribute to Bio-Larviciding in the Fight against Malaria: A Contingent Valuation Study among Rice Farmers in Rwanda. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:11575. [PMID: 34770086 PMCID: PMC8583195 DOI: 10.3390/ijerph182111575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 10/25/2021] [Accepted: 10/31/2021] [Indexed: 01/17/2023]
Abstract
There is broad consensus that successful and sustained larval source management (LSM) interventions, including bio-larviciding campaigns, require embeddedness in local community institutions. Ideally, these community structures should also be capable of mobilizing local resources to (co-)finance interventions. To date, farmer cooperatives, especially cooperatives of rice growers whose economic activity facilitates mosquito breeding, have remained under the radar in designing community-based bio-larviciding campaigns. This study explores the potential of rice farmer cooperatives in Bugesera district, Rwanda, to take up the aforementioned roles. To this purpose, we surveyed 320 randomly selected rice farmers who belonged to one of four rice cooperatives in the area and elicited their willingness-to-pay (WTP) for application of Bti, a popular bio-larvicide, in their rice paddies. Results from a (non-incentivized) bidding game procedure, which tested two alternative contribution schemes showed that financial contributions would be significantly different from zero and sufficient to carry a co-financing share of 15-25 per cent. A strong heterogeneity in mean WTP is revealed across cooperatives, in addition to variation among individual farmers, which needs to be anticipated when engaging farmer cooperatives in LSM.
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Affiliation(s)
- Alexis Rulisa
- Medical Research Centre Division, Rwanda Biomedical Centre, Kigali 7162, Rwanda;
- Department of Cultural Anthropology and Development Studies, Radboud University, 6525 Nijmegen, The Netherlands
| | - Luuk van Kempen
- Department of Cultural Anthropology and Development Studies, Radboud University, 6525 Nijmegen, The Netherlands
| | - Leon Mutesa
- Center for Human Genetics, College of Medicine and Health Sciences, University of Rwanda, Kigali 4285, Rwanda;
| | - Emmanuel Hakizimana
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali 7162, Rwanda;
| | - Chantal M. Ingabire
- Medical Research Centre Division, Rwanda Biomedical Centre, Kigali 7162, Rwanda;
| | - Fredrick Kateera
- Academic Medical Center, Department of Infectious Diseases, University of Amsterdam, 1012 Amsterdam, The Netherlands;
| | | | - Michèle van Vugt
- Center for Tropical Medicine and Travel Medicine, Academic Medical Center, University of Amsterdam, 1012 Amsterdam, The Netherlands;
| | - Bart van den Borne
- Department of Health Education & Promotion, Maastricht University, 6211 Maastricht, The Netherlands;
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Mysore K, Sun L, Hapairai LK, Wang CW, Igiede J, Roethele JB, Scheel ND, Scheel MP, Li P, Wei N, Severson DW, Duman-Scheel M. A Yeast RNA-Interference Pesticide Targeting the Irx Gene Functions as a Broad-Based Mosquito Larvicide and Adulticide. INSECTS 2021; 12:insects12110986. [PMID: 34821787 PMCID: PMC8622680 DOI: 10.3390/insects12110986] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 10/28/2021] [Accepted: 10/28/2021] [Indexed: 11/16/2022]
Abstract
Simple Summary It is critical that we identify new methods of preventing mosquito-borne infectious diseases, which threaten millions of people worldwide. In this investigation, we describe characterization of a new insecticide that turns off the mosquito Iroquois (Irx) gene, which is required for mosquito survival. The pesticide is synthesized in yeast, which can be fed to adult mosquitoes in a sugar bait solution or to juvenile mosquitoes that eat the yeast when it is placed in water where mosquitoes breed. Although the yeast kills several different types of mosquitoes, it was not found to affect the survival of other types of arthropods that consumed the yeast. These results indicate that yeast insecticides could one day be used for environmentally friendly mosquito control and disease prevention. Abstract Concerns for widespread insecticide resistance and the unintended impacts of insecticides on nontarget organisms have generated a pressing need for mosquito control innovations. A yeast RNAi-based insecticide that targets a conserved site in mosquito Irx family genes, but which has not yet been identified in the genomes of nontarget organisms, was developed and characterized. Saccharomyces cerevisiae constructed to express short hairpin RNA (shRNA) matching the target site induced significant Aedes aegypti larval death in both lab trials and outdoor semi-field evaluations. The yeast also induced high levels of mortality in adult females, which readily consumed yeast incorporated into an attractive targeted sugar bait (ATSB) during simulated field trials. A conserved requirement for Irx function as a regulator of proneural gene expression was observed in the mosquito brain, suggesting a possible mode of action. The larvicidal and adulticidal properties of the yeast were also verified in Aedes albopictus, Anopheles gambiae, and Culexquinquefasciatus mosquitoes, but the yeast larvicide was not toxic to other nontarget arthropods. These results indicate that further development and evaluation of this technology as an ecofriendly control intervention is warranted, and that ATSBs, an emerging mosquito control paradigm, could potentially be enriched through the use of yeast-based RNAi technology.
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Affiliation(s)
- Keshava Mysore
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, 1234 Notre Dame Ave., South Bend, IN 46617, USA; (K.M.); (L.S.); (L.K.H.); (J.B.R.); (M.P.S.); (P.L.); (D.W.S.)
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
| | - Longhua Sun
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, 1234 Notre Dame Ave., South Bend, IN 46617, USA; (K.M.); (L.S.); (L.K.H.); (J.B.R.); (M.P.S.); (P.L.); (D.W.S.)
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
| | - Limb K. Hapairai
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, 1234 Notre Dame Ave., South Bend, IN 46617, USA; (K.M.); (L.S.); (L.K.H.); (J.B.R.); (M.P.S.); (P.L.); (D.W.S.)
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
| | - Chien-Wei Wang
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
- Department of Civil and Environmental Engineering and Earth Sciences, The University of Notre Dame, Notre Dame, IN 46556, USA
| | - Jessica Igiede
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
- Department of Biological Sciences, The University of Notre Dame, Notre Dame, IN 46556, USA
| | - Joseph B. Roethele
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, 1234 Notre Dame Ave., South Bend, IN 46617, USA; (K.M.); (L.S.); (L.K.H.); (J.B.R.); (M.P.S.); (P.L.); (D.W.S.)
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
| | - Nicholas D. Scheel
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
- Department of Biological Sciences, The University of Notre Dame, Notre Dame, IN 46556, USA
| | - Max P. Scheel
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, 1234 Notre Dame Ave., South Bend, IN 46617, USA; (K.M.); (L.S.); (L.K.H.); (J.B.R.); (M.P.S.); (P.L.); (D.W.S.)
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
| | - Ping Li
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, 1234 Notre Dame Ave., South Bend, IN 46617, USA; (K.M.); (L.S.); (L.K.H.); (J.B.R.); (M.P.S.); (P.L.); (D.W.S.)
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
| | - Na Wei
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
- Department of Civil and Environmental Engineering and Earth Sciences, The University of Notre Dame, Notre Dame, IN 46556, USA
| | - David W. Severson
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, 1234 Notre Dame Ave., South Bend, IN 46617, USA; (K.M.); (L.S.); (L.K.H.); (J.B.R.); (M.P.S.); (P.L.); (D.W.S.)
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
- Department of Biological Sciences, The University of Notre Dame, Notre Dame, IN 46556, USA
- Department of Life Sciences, The University of the West Indies, St. Augustine, Trinidad, Trinidad and Tobago
| | - Molly Duman-Scheel
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Raclin-Carmichael Hall, 1234 Notre Dame Ave., South Bend, IN 46617, USA; (K.M.); (L.S.); (L.K.H.); (J.B.R.); (M.P.S.); (P.L.); (D.W.S.)
- Eck Institute for Global Health, The University of Notre Dame, Notre Dame, IN 46556, USA; (C.-W.W.); (J.I.); (N.D.S.); (N.W.)
- Correspondence:
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A Broad-Based Mosquito Yeast Interfering RNA Pesticide Targeting Rbfox1 Represses Notch Signaling and Kills Both Larvae and Adult Mosquitoes. Pathogens 2021; 10:pathogens10101251. [PMID: 34684200 PMCID: PMC8541554 DOI: 10.3390/pathogens10101251] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/21/2021] [Accepted: 09/23/2021] [Indexed: 12/03/2022] Open
Abstract
Prevention of mosquito-borne infectious diseases will require new classes of environmentally safe insecticides and novel mosquito control technologies. Saccharomyces cerevisiae was engineered to express short hairpin RNA (shRNA) corresponding to mosquito Rbfox1 genes. The yeast induced target gene silencing, resulting in larval death that was observed in both laboratory and outdoor semi-field trials conducted on Aedes aegypti. High levels of mortality were also observed during simulated field trials in which adult females consumed yeast delivered through a sugar bait. Mortality correlated with defects in the mosquito brain, in which a role for Rbfox1 as a positive regulator of Notch signaling was identified. The larvicidal and adulticidal activities of the yeast were subsequently confirmed in trials conducted on Aedes albopictus, Anopheles gambiae, and Culex quinquefasciatus, yet the yeast had no impact on survival of select non-target arthropods. These studies indicate that yeast RNAi pesticides targeting Rbfox1 could be further developed as broad-based mosquito larvicides and adulticides for deployment in integrated biorational mosquito control programs. These findings also suggest that the species-specificity of attractive targeted sugar baits, a new paradigm for vector control, could potentially be enhanced through RNAi technology, and specifically through the use of yeast-based interfering RNA pesticides.
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Antonio-Nkondjio C, Doumbe-Belisse P, Djamouko-Djonkam L, Ngadjeu CS, Talipouo A, Kopya E, Bamou R, Mayi MPA, Sonhafouo-Chiana N, Nkahe DL, Tabue R, Fosah DA, Bigoga JD, Awono-Ambene P, Wondji CS. High efficacy of microbial larvicides for malaria vectors control in the city of Yaounde Cameroon following a cluster randomized trial. Sci Rep 2021; 11:17101. [PMID: 34429446 PMCID: PMC8385066 DOI: 10.1038/s41598-021-96362-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/03/2021] [Indexed: 11/12/2022] Open
Abstract
The rapid expansion of insecticide resistance and outdoor malaria transmission are affecting the efficacy of current malaria control measures. In urban settings, where malaria transmission is focal and breeding habitats are few, fixed and findable, the addition of anti-larval control measures could be efficient for malaria vector control. But field evidences for this approach remains scarce. Here we provide findings of a randomized-control larviciding trial conducted in the city of Yaoundé that support the efficacy of this approach. A two arms random control trial design including 26 clusters of 2 to 4 km2 each (13 clusters in the intervention area and 13 in the non-intervention area) was used to assess larviciding efficacy. The microbial larvicide VectoMax combining Bacillus thuringiensis var israelensis (Bti) and Bacillus sphaericus in a single granule was applied every 2 weeks in all standing water collection points. The anopheline density collected using CDC light traps was used as the primary outcome, secondary outcomes included the entomological inoculation rate, breeding habitats with anopheline larvae, and larval density. Baseline entomological data collection was conducted for 17 months from March 2017 to July 2018 and the intervention lasted 26 months from September 2018 to November 2020. The intervention was associated with a reduction of 68% of adult anopheline biting density and of 79% of the entomological inoculation rate (OR 0.21; 95% CI 0.14-0.30, P < 0.0001). A reduction of 68.27% was recorded for indoor biting anophelines and 57.74% for outdoor biting anophelines. No impact on the composition of anopheline species was recorded. A reduction of over 35% of adult Culex biting densities was recorded. The study indicated high efficacy of larviciding for reducing malaria transmission intensity in the city of Yaoundé. Larviciding could be part of an integrated control approach for controlling malaria vectors and other mosquito species in the urban environment.
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Affiliation(s)
- Christophe Antonio-Nkondjio
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.
- Department of Vector Biology, Liverpool School of Tropical Medicine Pembroke Place, Liverpool, L3 5QA, UK.
| | - P Doumbe-Belisse
- Laboratoire de Recherche Sur Le Paludisme, 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
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
- Vector Borne Diseases Laboratory of the Biology and Applied Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang, Cameroon
| | - C S Ngadjeu
- Laboratoire de Recherche Sur Le Paludisme, 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
| | - A Talipouo
- Laboratoire de Recherche Sur Le Paludisme, 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
- Laboratoire de Recherche Sur Le Paludisme, 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
| | - R Bamou
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
- Vector Borne Diseases Laboratory of the Biology and Applied Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang, Cameroon
| | - M P Audrey Mayi
- Vector Borne Diseases Laboratory of the Biology and Applied Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang, Cameroon
| | - N Sonhafouo-Chiana
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
- Faculty of Sciences, University of Buea, P.O. Box 63, Buea, Cameroon
| | - D L Nkahe
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - R Tabue
- Ministry of Public Health, National Malaria Control Programme, Yaoundé, Cameroon
| | - D Achu Fosah
- Ministry of Public Health, National Malaria Control Programme, Yaoundé, Cameroon
| | - Jude D Bigoga
- Laboratory for Vector Biology and Control, National Reference Unit for Vector Control, The Biotechnology Center, Nkolbisson-University of Yaounde I, P.O. Box 3851, Messa, Yaoundé, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaounde I, Yaoundé, Cameroon
| | - P Awono-Ambene
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
| | - Charles S Wondji
- Department of Vector Biology, Liverpool School of Tropical Medicine Pembroke Place, Liverpool, L3 5QA, UK
- Centre for Research in Infectious Diseases, Yaoundé, Cameroon
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Carvalho KDS, Guedes DRD, Crespo MM, de Melo-Santos MAV, Silva-Filha MHNL. Aedes aegypti continuously exposed to Bacillus thuringiensis svar. israelensis does not exhibit changes in life traits but displays increased susceptibility for Zika virus. Parasit Vectors 2021; 14:379. [PMID: 34321098 PMCID: PMC8317411 DOI: 10.1186/s13071-021-04880-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 07/16/2021] [Indexed: 11/20/2022] Open
Abstract
Background Aedes aegypti can transmit arboviruses worldwide, and Bacillus thuringiensis svar. israelensis (Bti)-based larvicides represent an effective tool for controlling this species. The safety of Bti and lack of resistance have been widely reported; however, little is known regarding the impact of the extensive use of these larvicides on the life traits of mosquitoes. Therefore, this study investigated biological parameters, including susceptibility to arbovirus, of an Ae. aegypti strain (RecBti) subjected to 29 generations of exposure to Bti compared with the RecL reference strain. Methods The biological parameters of individuals reared under controlled conditions were compared. Also, the viral susceptibility of females not exposed to Bti during their larval stage was analysed by oral infection and followed until 14 or 21 days post-infection (dpi). Results RecBti individuals did not display alterations in the traits that were assessed (fecundity, fertility, pupal weight, developmental time, emergence rate, sex ratio and haematophagic capacity) compared to RecL individuals. Females from both strains were susceptible to dengue serotype 2 (DENV-2) and Zika virus (ZIKV). However, RecBti females showed significantly higher rates of ZIKV infection compared with RecL females at 7 (90% versus 68%, Chi-square: χ2 = 7.27, df = 1, P = 0.006) and 14 dpi (100% versus 87%, Chi-square: χ2 = 7.69, df = 1, P = 0.005) and for dissemination at 7 dpi (83.3% versus 36%, Fisher’s exact test: P < 0.0001, OR = 0.11, 95% CI 0.03–0.32). Quantification of DENV-2 and ZIKV viral particles produced statistically similar results for females from both strains. Conclusions Prolonged exposure of Ae. aegypti larvae to Bti did not alter most of the evaluated biological parameters, except that RecBti females exhibited a higher vector susceptibility for ZIKV. This finding is related to a background of Bti exposure for several generations but not to a previous exposure of the tested females during the larval stage. This study highlights mosquito responses that could be associated with the chronic exposure to Bti in addition to the primary larvicidal effect elicited by this control agent. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04880-6.
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Affiliation(s)
| | | | - Mônica Maria Crespo
- Department of Entomology, Instituto Aggeu Magalhães-Fiocruz, Recife, Pernambuco, Brazil
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Runge M, Mapua S, Nambunga I, Smith TA, Chitnis N, Okumu F, Pothin E. Evaluation of different deployment strategies for larviciding to control malaria: a simulation study. Malar J 2021; 20:324. [PMID: 34315473 PMCID: PMC8314573 DOI: 10.1186/s12936-021-03854-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 07/16/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Larviciding against malaria vectors in Africa has been limited to indoor residual spraying and insecticide-treated nets, but is increasingly being considered by some countries as a complementary strategy. However, despite progress towards improved larvicides and new tools for mapping or treating mosquito-breeding sites, little is known about the optimal deployment strategies for larviciding in different transmission and seasonality settings. METHODS A malaria transmission model, OpenMalaria, was used to simulate varying larviciding strategies and their impact on host-seeking mosquito densities, entomological inoculation rate (EIR) and malaria prevalence. Variations in coverage, duration, frequency, and timing of larviciding were simulated for three transmission intensities and four transmission seasonality profiles. Malaria transmission was assumed to follow rainfall with a lag of one month. Theoretical sub-Saharan African settings with Anopheles gambiae as the dominant vector were chosen to explore impact. Relative reduction compared to no larviciding was predicted for each indicator during the simulated larviciding period. RESULTS Larviciding immediately reduced the predicted host-seeking mosquito densities and EIRs to a maximum that approached or exceeded the simulated coverage. Reduction in prevalence was delayed by approximately one month. The relative reduction in prevalence was up to four times higher at low than high transmission. Reducing larviciding frequency (i.e., from every 5 to 10 days) resulted in substantial loss in effectiveness (54, 45 and 53% loss of impact for host-seeking mosquito densities, EIR and prevalence, respectively). In seasonal settings the most effective timing of larviciding was during or at the beginning of the rainy season and least impactful during the dry season, assuming larviciding deployment for four months. CONCLUSION The results highlight the critical role of deployment strategies on the impact of larviciding. Overall, larviciding would be more effective in settings with low and seasonal transmission, and at the beginning and during the peak densities of the target species populations. For maximum impact, implementers should consider the practical ranges of coverage, duration, frequency, and timing of larviciding in their respective contexts. More operational data and improved calibration would enable models to become a practical tool to support malaria control programmes in developing larviciding strategies that account for the diversity of contexts.
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Affiliation(s)
- Manuela Runge
- Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Salum Mapua
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Ismail Nambunga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Thomas A Smith
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Nakul Chitnis
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Fredros Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Emilie Pothin
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland.,Clinton Health Access Initiative, Boston, USA
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Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance. Toxins (Basel) 2021; 13:toxins13080523. [PMID: 34437394 PMCID: PMC8402332 DOI: 10.3390/toxins13080523] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/18/2021] [Accepted: 06/19/2021] [Indexed: 12/25/2022] Open
Abstract
Larvicides based on the bacteria Bacillus thuringiensis svar. israelensis (Bti) and Lysinibacillus sphaericus are effective and environmentally safe compounds for the control of dipteran insects of medical importance. They produce crystals that display specific and potent insecticidal activity against larvae. Bti crystals are composed of multiple protoxins: three from the three-domain Cry type family, which bind to different cell receptors in the midgut, and one cytolytic (Cyt1Aa) protoxin that can insert itself into the cell membrane and act as surrogate receptor of the Cry toxins. Together, those toxins display a complex mode of action that shows a low risk of resistance selection. L. sphaericus crystals contain one major binary toxin that display an outstanding persistence in field conditions, which is superior to Bti. However, the action of the Bin toxin based on its interaction with a single receptor is vulnerable for resistance selection in insects. In this review we present the most recent data on the mode of action and synergism of these toxins, resistance issues, and examples of their use worldwide. Data reported in recent years improved our understanding of the mechanism of action of these toxins, showed that their combined use can enhance their activity and counteract resistance, and reinforced their relevance for mosquito control programs in the future years.
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Dambach P, Bärnighausen T, Yadouleton A, Dambach M, Traoré I, Korir P, Ouedraogo S, Nikiema M, Sauerborn R, Becker N, Louis VR. Is biological larviciding against malaria a starting point for integrated multi-disease control? Observations from a cluster randomized trial in rural Burkina Faso. PLoS One 2021; 16:e0253597. [PMID: 34143831 PMCID: PMC8213177 DOI: 10.1371/journal.pone.0253597] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 06/08/2021] [Indexed: 11/29/2022] Open
Abstract
Objectives To evaluate the impact of anti-malaria biological larviciding with Bacillus thuringiensis israelensis on non-primary target mosquito species in a rural African setting. Methods A total of 127 villages were distributed in three study arms, each with different larviciding options in public spaces: i) no treatment, ii) full or iii) guided intervention. Geographically close villages were grouped in clusters to avoid contamination between treated and untreated villages. Adult mosquitoes were captured in light traps inside and outside houses during the rainy seasons of a baseline and an intervention year. After enumeration, a negative binomial regression was used to determine the reductions achieved in the different mosquito species through larviciding. Results Malaria larviciding interventions showed only limited or no impact against Culex mosquitoes; by contrast, reductions of up to 34% were achieved against Aedes when all detected breeding sites were treated. Culex mosquitoes were captured in high abundance in semi-urban settings while more Aedes were found in rural villages. Conclusions Future malaria larviciding programs should consider expanding onto the breeding habitats of other disease vectors, such as Aedes and Culex and evaluate their potential impact. Since the major cost components of such interventions are labor and transport, other disease vectors could be targeted at little additional cost.
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Affiliation(s)
- Peter Dambach
- Institute for Global Health, University Hospital Heidelberg, Heidelberg, Germany
- * E-mail:
| | - Till Bärnighausen
- Institute for Global Health, University Hospital Heidelberg, Heidelberg, Germany
| | - Anges Yadouleton
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Martin Dambach
- Institute of Zoology, University of Cologne, Cologne, Germany
| | - Issouf Traoré
- Centre de Recherche en Santé de Nouna, Nouna, Burkina Faso
| | - Patricia Korir
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | | | | | - Rainer Sauerborn
- Institute for Global Health, University Hospital Heidelberg, Heidelberg, Germany
| | - Norbert Becker
- German Mosquito Control Association (KABS), Speyer, Germany
| | - Valérie R. Louis
- Institute for Global Health, University Hospital Heidelberg, Heidelberg, Germany
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Wu P, Tang X, Jian R, Li J, Lin M, Dai H, Wang K, Sheng Z, Chen B, Xu X, Li C, Lin Z, Zhang Q, Zheng X, Zhang K, Li D, Hong WD. Chemical Composition, Antimicrobial and Insecticidal Activities of Essential Oils of Discarded Perfume Lemon and Leaves ( Citrus Limon (L.) Burm. F.) as Possible Sources of Functional Botanical Agents. Front Chem 2021; 9:679116. [PMID: 34109157 PMCID: PMC8184092 DOI: 10.3389/fchem.2021.679116] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/06/2021] [Indexed: 11/13/2022] Open
Abstract
Two essential oils were isolated from discarded perfume lemon and leaves (Citrus limon (L.) Burm. F.) by hydro-distillation with good yield (0.044% for perfume lemon and 0.338% for leaves). Their biological activities were evaluated against five selected bacterial strains and Aedes albopictus (Ae. albopictus, Diptera: Culicidae). Chemical composition indicated that both essential oils were rich in essential phytochemicals including hydrocarbons, monoterpenes and sesquiterpene. These constituents revealed some variability among the oils displaying interesting chemotypes (R)-(+)-limonene (12.29–49.63%), citronellal (5.37–78.70%) and citronellol (2.98–7.18%). The biological assessments proved that the two essential oils had similar effect against bacterial (inhibition zones diameter ranging from 7.27 ± 0.06 to 10.37 ± 0.15 mm; MICs and MBCs ranging from 1.6 to 6.4 mg/mL); against Ae. albopictus larvae (LC50 ranging from 384.81 to 395.09 ppm) and adult mosquito (LD50 ranging from 133.059 to 218.962 μg/cm2); the activity of the two chemotypes ((R)-(+)-limonene and citronellal): larvae (LC50 ranging from 267.08 to 295.28 ppm), which were all presented in dose-dependent manners. Through this work, we have showcased that recycling and reusing of agriculture by-products, such as discarded perfume lemon and leaves can produce eco-friendly alternatives in bacterial disinfectants and mosquito control product.
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Affiliation(s)
- Panpan Wu
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Xiaowen Tang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Rongchao Jian
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Jiahao Li
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Maoyu Lin
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Huachao Dai
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Kangpeng Wang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Zhaojun Sheng
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Baizhong Chen
- Guangdong Xinbaotang Biotechnology Co. Ltd., Jiangmen, China
| | - Xuetao Xu
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Chen Li
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Zhongze Lin
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Qingmin Zhang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Xi Zheng
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Kun Zhang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Dongli Li
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China
| | - Weiqian David Hong
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, China.,International Healthcare Innovation Institute (Jiangmen), Jiangmen, China.,Department of Chemistry, University of Liverpool, Liverpool, United Kingdom
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Hinne IA, Attah SK, Mensah BA, Forson AO, Afrane YA. Larval habitat diversity and Anopheles mosquito species distribution in different ecological zones in Ghana. Parasit Vectors 2021; 14:193. [PMID: 33827667 PMCID: PMC8025514 DOI: 10.1186/s13071-021-04701-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/23/2021] [Indexed: 11/16/2022] Open
Abstract
Background Understanding the ecology of larval malaria and lymphatic filariasis mosquitoes in a changing environment is important in developing effective control tools or programmes. This study characterized the breeding habitats of Anopheles mosquitoes in rural communities in different ecological zones in Ghana during the dry and rainy seasons. Methods The spatio-temporal distribution, species composition, and abundance of larval Anopheles mosquitoes in breeding habitats were studied in five locations in three ecological zones of Ghana. These were Anyakpor (coastal savannah area), Duase (forest area), and Libga, Pagaza, and Kpalsogu (Sahel savannah area). Larvae were collected using standard dippers and were raised in the insectary for identification. Results Out of a total of 7984 mosquito larvae collected, 2152 (27.26%) were anophelines and were more abundant in the rainy season (70.82%) than in the dry season (29.18%). The anophelines comprised 2128 (98.88%) An. gambiae s.l., 16 (0.74%) An. rufipes, and 8 (0.37%) An. pharoensis. In the coastal savannah and forest zones, dug-out wells were the most productive habitat during the dry (1.59 larvae/dip and 1.47 larvae/dip) and rainy seasons (11.28 larvae/dip and 2.05 larvae/dip). Swamps and furrows were the most productive habitats in the Sahel savannah zone during the dry (0.25 larvae/dip) and rainy (2.14 larvae/dip) seasons, respectively. Anopheles coluzzii was the most abundant sibling species in all the ecological zones. Anopheles melas and An. arabiensis were encountered only in the coastal savannah and the Sahel savannah areas, respectively. Larval habitat types influenced the presence of larvae as well as larval density (p < 0.001). The land-use type affected the presence of Anopheles larvae (p = 0.001), while vegetation cover influenced larval density (p < 0.05). Conclusion The most productive habitats were dug-out wells in the coastal savannah and forest zones, and furrows from irrigated canals in the Sahel savannah zone. Anopheles coluzzii was the predominant vector species in all the ecological zones. The abundance of Anopheles breeding habitats and larvae were influenced by anthropogenic activities. Encouraging people whose activities create the larval habitats to become involved in larval source management such as habitat manipulation to stop mosquito breeding will be important for malaria and lymphatic filariasis control. Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04701-w.
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Affiliation(s)
- Isaac A Hinne
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Simon K Attah
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Benedicta A Mensah
- Department of Epidemiology, Noguchi Memorial Institute of Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Akua O Forson
- Department of Medical Laboratory Science, School of Biomedical and Allied Health Sciences, University of Ghana, Korle-Bu, Accra, Ghana
| | - Yaw A Afrane
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana.
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Mwingira V, Mboera LEG, Dicke M, Takken W. Exploiting the chemical ecology of mosquito oviposition behavior in mosquito surveillance and control: a review. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2020; 45:155-179. [PMID: 33207066 DOI: 10.1111/jvec.12387] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Vector control is an important component of the interventions aimed at mosquito-borne disease control. Current and future mosquito control strategies are likely to rely largely on the understanding of the behavior of the vector, by exploiting mosquito biology and behavior, while using cost-effective, carefully timed larvicidal and high-impact, low-volume adulticidal applications. Here we review the knowledge on the ecology of mosquito oviposition behavior with emphasis on the potential role of infochemicals in surveillance and control of mosquito-borne diseases. A search of PubMed, Embase, Web of Science, Global Health Archive, and Google Scholar databases was conducted using the keywords mosquito, infochemical, pheromone, kairomone, allomone, synomone, apneumone, attractant, host-seeking, and oviposition. Articles in English from 1974 to 2019 were reviewed to gain comprehensive understanding of current knowledge on infochemicals in mosquito resource-searching behavior. Oviposition of many mosquito species is mediated by infochemicals that comprise pheromones, kairomones, synomones, allomones, and apneumones. The novel putative infochemicals that mediate oviposition in the mosquito subfamilies Anophelinae and Culicinae were identified. The role of infochemicals in surveillance and control of these and other mosquito tribes is discussed with respect to origin of the chemical cues and how these affect gravid mosquitoes. Oviposition attractants and deterrents can potentially be used for manipulation of mosquito behavior by making protected resources unsuitable for mosquitoes (push) while luring them towards attractive sources (pull). In this review, strategies of targeting breeding sites with environmentally friendly larvicides with the aim to develop appropriate trap-and-kill techniques are discussed.
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Affiliation(s)
- Victor Mwingira
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
- National Institute for Medical Research, Amani Research Centre, P.O. Box 81, Muheza, Tanzania
| | - Leonard E G Mboera
- SACIDS Foundation for One Health, Sokoine University of Agriculture, P.O. Box 3297 Chuo Kikuu, Morogoro, Tanzania
| | - Marcel Dicke
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research, P.O. Box 16, 6700 AA, Wageningen, The Netherlands
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Gimnig JE, Ombok M, Bayoh N, Mathias D, Ochomo E, Jany W, Walker ED. Efficacy of extended release formulations of Natular™ (spinosad) against larvae and adults of Anopheles mosquitoes in western Kenya. Malar J 2020; 19:436. [PMID: 33243237 PMCID: PMC7691113 DOI: 10.1186/s12936-020-03507-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 11/18/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Larval source management is recommended as a supplementary vector control measure for the prevention of malaria. Among the concerns related to larviciding is the feasibility of implementation in tropical areas with large numbers of habitats and the need for frequent application. Formulated products of spinosad that are designed to be effective for several weeks may mitigate some of these concerns. METHODS In a semi-field study, three formulations of spinosad (emulsifiable concentrate, extended release granules and tablet formulations) were tested in naturalistic habitats in comparison to an untreated control. Cohorts of third instar Anopheles gambiae (Diptera: Culicidae) were introduced into the habitats in screened cages every week up to four weeks after application and monitored for survivorship over three days. A small-scale field trial was then conducted in two villages. Two of the spinosad formulations were applied in one village over the course of 18 months. Immature mosquito populations were monitored with standard dippers in sentinel sites and adult populations were monitored by pyrethrum spray catches. RESULTS In the semi-field study, the efficacy of the emulsifiable concentrate of spinosad waned 1 week after treatment. Mortality in habitats treated with the extended release granular formulation of spinosad was initially high but declined gradually over 4 weeks while mortality in habitats treated with the dispersable tablet formulation was low immediately after treatment but rose to 100% through four weeks. In the field study, immature and adult Anopheles mosquito populations were significantly lower in the intervention village compared to the control village during the larviciding period. Numbers of collected mosquitoes were lower in the intervention village compared to the control village during the post-intervention period but the difference was not statistically significant. CONCLUSIONS The extended release granular formulation and the dispersible tablet formulations of spinosad are effective against larval Anopheles mosquitoes for up to four weeks and may be an effective tool as part of larval source management programmes for reducing adult mosquito density and malaria transmission.
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Affiliation(s)
- John E Gimnig
- Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Atlanta, GA, USA.
| | - Maurice Ombok
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Nabie Bayoh
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
- PMI VectorLink Project, Abt Associates, Lusaka, Zambia
| | - Derrick Mathias
- Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Atlanta, GA, USA
- Florida Medical Entomological Laboratory, University of Florida, Vero Beach, FL, USA
| | - Eric Ochomo
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | | | - Edward D Walker
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
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Rocha EM, Katak RDM, Campos de Oliveira J, Araujo MDS, Carlos BC, Galizi R, Tripet F, Marinotti O, Souza-Neto JA. Vector-Focused Approaches to Curb Malaria Transmission in the Brazilian Amazon: An Overview of Current and Future Challenges and Strategies. Trop Med Infect Dis 2020; 5:E161. [PMID: 33092228 PMCID: PMC7709627 DOI: 10.3390/tropicalmed5040161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/10/2020] [Accepted: 10/13/2020] [Indexed: 01/05/2023] Open
Abstract
In Brazil, malaria transmission is mostly confined to the Amazon, where substantial progress has been made towards disease control in the past decade. Vector control has been historically considered a fundamental part of the main malaria control programs implemented in Brazil. However, the conventional vector-control tools have been insufficient to control or eliminate local vector populations due to the complexity of the Amazonian rainforest environment and ecological features of malaria vector species in the Amazon, especially Anopheles darlingi. Malaria elimination in Brazil and worldwide eradication will require a combination of conventional and new approaches that takes into account the regional specificities of vector populations and malaria transmission dynamics. Here we present an overview on both conventional and novel promising vector-focused tools to curb malaria transmission in the Brazilian Amazon. If well designed and employed, vector-based approaches may improve the implementation of malaria-control programs, particularly in remote or difficult-to-access areas and in regions where existing interventions have been unable to eliminate disease transmission. However, much effort still has to be put into research expanding the knowledge of neotropical malaria vectors to set the steppingstones for the optimization of conventional and development of innovative vector-control tools.
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Affiliation(s)
- Elerson Matos Rocha
- Programa de Pós-Graduação em Biotecnologia, Universidade Federal do Amazonas—PPGBIOTEC/UFAM, Manaus 69067-005, Brazil; (E.M.R.); (R.d.M.K.); (J.C.d.O.)
| | - Ricardo de Melo Katak
- Programa de Pós-Graduação em Biotecnologia, Universidade Federal do Amazonas—PPGBIOTEC/UFAM, Manaus 69067-005, Brazil; (E.M.R.); (R.d.M.K.); (J.C.d.O.)
| | - Juan Campos de Oliveira
- Programa de Pós-Graduação em Biotecnologia, Universidade Federal do Amazonas—PPGBIOTEC/UFAM, Manaus 69067-005, Brazil; (E.M.R.); (R.d.M.K.); (J.C.d.O.)
| | - Maisa da Silva Araujo
- Laboratory of Medical Entomology, Oswaldo Cruz Foundation, FIOCRUZ RONDONIA, Porto Velho, RO 76812-245, Brazil;
| | - Bianca Cechetto Carlos
- Department of Bioprocesses and Biotechnology, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil;
- Central Multiuser Laboratory, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil
| | - Roberto Galizi
- Centre of Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire ST5 5GB, UK; (R.G.); (F.T.)
| | - Frederic Tripet
- Centre of Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire ST5 5GB, UK; (R.G.); (F.T.)
| | | | - Jayme A. Souza-Neto
- Department of Bioprocesses and Biotechnology, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil;
- Central Multiuser Laboratory, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil
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Are Individuals Willing to Pay for Community-Based Eco-Friendly Malaria Vector Control Strategies? A Case of Mosquito Larviciding Using Plant-Based Biopesticides in Kenya. SUSTAINABILITY 2020. [DOI: 10.3390/su12208552] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This study was carried out to assess individuals’ willingness to pay (WTP) for UZIMAX, a novel plant-based biopesticide developed for malaria vector control. The biopesticide is estimated to kill up to 100% of Anopheles larvae within 48 h of application and poses no risks to human health and the environment. However, scaling-up of its adoption requires clear evidence of its acceptance by individuals in malaria-prone areas. We conducted Becker-DeGroot-Marschak (BDM) revealed preference auctions with 204 participants to determine their willingness to pay (WTP) for community-based application of the biopesticide to control malaria vectors. Nearly all participants were willing to pay at the lowest bid price of the biopesticide, and the majority of them expressed great interest in pooling resources to facilitate biopesticide application. Household per capita income and building capacity of households through training significantly increased WTP. These findings imply high adoption potential of the technology and the need to devise inclusive policy tools, especially those that enhance collective action, resource mobilization and capacity building to empower both men and women and stimulate investment in eco-friendly technologies for malaria prevention. Financial and labor resource mechanisms managed by the community could potentially spur adoption of the biopesticides, and in turn, generate health, environmental and economic benefits to households in malaria-prone communities.
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Elanga-Ndille E, Binyang A, Ndo C, Assatse T, Nouage L, Tchouakui M, Tene-Fossog B, Kekeunou S, Wondji CS. Entomological indicators of malaria transmission and insecticide resistance profile of Anopheles gambiae at the early phase of irrigated rice farming in the forest area of central Cameroon. Wellcome Open Res 2020. [DOI: 10.12688/wellcomeopenres.16064.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Background:Cameroonian authorities have recently established irrigated rice projects across the country. The assessment of the impact of such projects in the transmission of vector-borne diseases, such as malaria, imposes to compare the situation before and after their implementation in a given locality. In Bankeng, a village in a forest area in Cameroon, no preliminary data on malaria transmission indicators was collected before the implantation of irrigated rice farming. To attempt to catch up for this shortcoming 6 months after the first rice seedlings were sown., the present study aimed to generate data which could serve as a baseline to assess the impact of irrigated rice farming in Bankeng.Methods: A cross-sectional study was performed at the end of the rainy season in July 2018. Mosquitoes were sampled by night collections on human volunteers, identified morphologically and members of different complexes further sorted to species using molecular tools.Plasmodiuminfectious status was determined by Taqman genotyping. To assess resistance profile to insecticides, WHO bioassays were performed using two-to-five days old femalesAn. gambiaes.l. reared from larval collections in Bankeng. Furthermore, the molecular basis of resistance were investigatedResults:An. gambiaes.l represented 98% of the 1087 mosquitoes collected withAnopheles gambiaeas the predominant species. The total human biting rate was 44.5 bites/person/night. Entomological inoculation rate was 3.8 ib/p/n. The BankengAn. gambiaepopulation exhibited a high level of resistance to almost all insecticides except to organophosphates with a high frequency of L1014F kdr mutation (93.9%) and a 6-fold over-expression ofCYP6P3P450 gene. Conclusion: In the absence of preliminary data before the implementation of the irrigated rice fields; the present study provides interesting data which could help for the future assessment of the impact of irrigated rice cultivation on malaria transmission in the locality of Bankeng.
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Finda MF, Christofides N, Lezaun J, Tarimo B, Chaki P, Kelly AH, Kapologwe N, Kazyoba P, Emidi B, Okumu FO. Opinions of key stakeholders on alternative interventions for malaria control and elimination in Tanzania. Malar J 2020; 19:164. [PMID: 32321534 PMCID: PMC7178586 DOI: 10.1186/s12936-020-03239-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/16/2020] [Indexed: 03/03/2023] Open
Abstract
Background Malaria control in Tanzania currently relies primarily on long-lasting insecticidal nets and indoor residual spraying, alongside effective case management and behaviour change communication. This study explored opinions of key stakeholders on the national progress towards malaria elimination, the potential of currently available vector control interventions in helping achieve elimination by 2030, and the need for alternative interventions that could be used to supplement malaria elimination efforts in Tanzania. Methods In this exploratory qualitative study, Focus group discussions were held with policy-makers, regulators, research scientists and community members. Malaria control interventions discussed were: (a) improved housing, (b) larval source management, (c) mass drug administration (MDA) with ivermectin to reduce vector densities, (d) release of modified mosquitoes, including genetically modified or irradiated mosquitoes, (e) targeted spraying of mosquito swarms, and (f) spatial repellents. Results Larval source management and spatial repellents were widely supported across all stakeholder groups, while insecticide-spraying of mosquito swarms was the least preferred. Support for MDA with ivermectin was high among policy makers, regulators and research scientists, but encountered opposition among community members, who instead expressed strong support for programmes to improve housing for poor people in high transmission areas. Policy makers, however, challenged the idea of government-supported housing improvement due to its perceived high costs. Techniques of mosquito modification, specifically those involving gene drives, were viewed positively by community members, policy makers and regulators, but encountered a high degree of scepticism among scientists. Overall, policy-makers, regulators and community members trusted scientists to provide appropriate advice for decision-making. Conclusion Stakeholder opinions regarding alternative malaria interventions were divergent except for larval source management and spatial repellents, for which there was universal support. MDA with ivermectin, housing improvement and modified mosquitoes were also widely supported, though each faced concerns from at least one stakeholder group. While policy-makers, regulators and community members all noted their reliance on scientists to make informed decisions, their reasoning on the benefits and disadvantages of specific interventions included factors beyond technical efficiency. This study suggests the need to encourage and strengthen dialogue between research scientists, policy makers, regulators and communities regarding new interventions.
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Affiliation(s)
- Marceline F Finda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania. .,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 1 Smuts Avenue, Braamfontein, 2000, South Africa.
| | - Nicola Christofides
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 1 Smuts Avenue, Braamfontein, 2000, South Africa
| | - Javier Lezaun
- Institute for Science, Innovation and Society, School of Anthropology and Museum Ethnography, University of Oxford, Oxford, UK
| | - Brian Tarimo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Prosper Chaki
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Ann H Kelly
- Department of Global Health and Social Medicine, King's College, London, UK
| | - Ntuli Kapologwe
- President's Office, Regional Administration and Local Government, P. O Box 1923, Dodoma, Tanzania
| | - Paul Kazyoba
- National Institute for Medical Research, 3 Barack Obama Drive, Dar es Salaam, Tanzania
| | - Basiliana Emidi
- National Institute for Medical Research, 3 Barack Obama Drive, Dar es Salaam, Tanzania.,National Malaria Control Programme, P. O. Box 743, Dodoma, Tanzania
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 1 Smuts Avenue, Braamfontein, 2000, South Africa.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.,School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania
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