36 results on '"Dadzie, Samuel"'
Search Results
2. Molecular identification of cattle ticks in the Greater Accra Region of Ghana: a high occurrence of Rhipicephalus microplus
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Tawiah-Mensah, Christopher Nii Laryea, Addo, Seth Offei, Ansah-Owusu, Jane, Abudu, Mufeez, Malm, Richard Odoi-Teye, Yartey, Kevin Nii, Oduro, Daniel, Akorli, Jewelna, and Dadzie, Samuel K.
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- 2024
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3. Tick-borne pathogens of zoonotic and veterinary importance in cattle ticks in Ghana
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Ansah-Owusu, Jane, Addo, Seth Offei, Tawiah-Mensah, Christopher Nii Laryea, Obuam, Patrick Kwasi, Malm, Richard Odoi-Teye, Yartey, Kevin Nii, Yanney, Jennifer Nyamekye, Torto, Francisca Adai, Accorlor, Stephen Kwabena, and Dadzie, Samuel K.
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- 2024
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4. Estimating malaria transmission risk through surveillance of human–vector interactions in northern Ghana
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Coleman, Sylvester, Yihdego, Yemane, Gyamfi, Frank, Kolyada, Lena, Tongren, Jon Eric, Zigirumugabe, Sixte, Dery, Dominic B., Badu, Kingsley, Obiri-Danso, Kwasi, Boakye, Daniel, Szumlas, Daniel, Armistead, Jennifer S., and Dadzie, Samuel K.
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- 2023
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5. Occurrence of Rickettsia spp. and Coxiella burnetii in ixodid ticks in Kassena-Nankana, Ghana
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Addo, Seth Offei, Bentil, Ronald Essah, Baako, Bernice Olivia Ama, Yartey, Kevin Nii, Behene, Eric, Asiamah, Benjamin, Nyarko, Abena Akyeamaa, Asoala, Victor, Sallam, Mohamed, Mate, Suzanne, Dunford, James C., Larbi, John Asiedu, Baidoo, Philip Kweku, Wilson, Michael David, Diclaro II, Joseph W., and Dadzie, Samuel K.
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- 2023
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6. First record of Rhipicephalus (Boophilus) microplus in Ghana, a potential risk to livestock production
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Addo, Seth Offei, Bentil, Ronald Essah, Baako, Bernice Olivia Ama, Addae, Charlotte Adwoa, Larbi, John Asiedu, Baidoo, Philip Kweku, Wilson, Michael David, Asoala, Victor, Oduro, Daniel, Mate, Suzanne, Diclaro II, Joseph W., and Dadzie, Samuel K.
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- 2023
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7. Molecular survey of Anaplasma and Ehrlichia species in livestock ticks from Kassena-Nankana, Ghana; with a first report of Anaplasma capra and Ehrlichia minasensis
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Addo, Seth Offei, Baako, Bernice Olivia Ama, Bentil, Ronald Essah, Addae, Charlotte Adwoa, Behene, Eric, Asoala, Victor, Sallam, Mohamed, Mate, Suzanne, Dunford, James C., Larbi, John Asiedu, Baidoo, Philip Kweku, Wilson, Michael David, Diclaro, II, Joseph W., and Dadzie, Samuel K.
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- 2023
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8. Social networking and risk attitudes nexus: implication for technology adoption among smallholder cassava farmers in Ghana
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Dadzie, Samuel K. N., Ndebugri, Joseph, Inkoom, Emmanuel W., and Akuamoah-Boateng, Samuel
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- 2022
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9. Ticks and prevalence of tick-borne pathogens from domestic animals in Ghana
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Nimo-Paintsil, Shirley C., Mosore, Mba, Addo, Seth Offei, Lura, Taylor, Tagoe, Janice, Ladzekpo, Danielle, Addae, Charlotte, Bentil, Ronald E., Behene, Eric, Dafeamekpor, Courage, Asoala, Victor, Fox, Anne, Watters, Chaselynn M., Koehler, Jeffrey W., Schoepp, Randy J., Arimoto, Hanayo, Dadzie, Samuel, Letizia, Andrew, and Diclaro, II, Joseph W.
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- 2022
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10. Sustainability responses to climate-smart adaptation in Africa: implication for food security among farm households in the Central Region of Ghana
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Dadzie, Samuel Kwesi Ndzebah, Inkoom, Emmanuel W., Akaba, Selorm, Annor-Frempong, Festus, and Afful, James
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- 2021
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11. Determining vector competence of Aedes aegypti from Ghana in transmitting dengue virus serotypes 1 and 2
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Amoa-Bosompem, Michael, Kobayashi, Daisuke, Itokawa, Kentaro, Murota, Katsunori, Faizah, Astri Nur, Azerigyik, Faustus Akankperiwen, Hayashi, Takaya, Ohashi, Mitsuko, Bonney, Joseph H. Kofi, Dadzie, Samuel, Tran, Cuong Chi, Tran, Phong Vu, Fujita, Ryosuke, Maekawa, Yoshihide, Kasai, Shinji, Yamaoka, Shoji, Ohta, Nobuo, Sawabe, Kyoko, Iwanaga, Shiroh, and Isawa, Haruhiko
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- 2021
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12. The future of youth tourism in Ghana: motives, satisfaction and behavioural intentions
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Preko, Alexander, Doe, Frederick, and Dadzie, Samuel Ato
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- 2019
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13. Potential factors influencing lymphatic filariasis transmission in “hotspot” and “control” areas in Ghana: the importance of vectors
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Pi-Bansa, Sellase, Osei, Joseph Harold Nyarko, Frempong, Kwadwo Kyeremeh, Elhassan, Elizabeth, Akuoko, Osei Kweku, Agyemang, David, Ahorlu, Collins, Appawu, Maxwell Alexander, Koudou, Benjamin Guibehi, Wilson, Michael David, de Souza, Dziedzom Komi, Dadzie, Samuel Kweku, Utzinger, Jürg, and Boakye, Daniel Adjei
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- 2019
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14. Examining drivers of technical, allocative and economic efficiencies in cocoa farming: empirical evidence from Ghana
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Inkoom, Emmanuel W., Acquah , Henry D., and Dadzie, Samuel K. N.
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Stochastic Frontier Analysis ,Economic efficiency ,efficiency drivers ,cocoa production ,Ghana ,General Medicine - Abstract
In Ghana, cocoa production is a major economic activity among rural farmers. Its production contributes significantly to the GDP and further, livelihood security enhancement among rural folks. However, recent development has unveiled a situation of persistent low farm-level productivity among cocoa farmers which threatens their livelihood security. In view of this, we estimated the economic, technical, and allocative efficiencies among cocoa farmers and their determinants to help proffer relevant policy strategies to arrest the situation of low farm-level productivity. Using a multistage sampling procedure, we collected data from 750 cocoa farmers across the cocoa-growing regions of Ghana. To estimate the farm-level efficiency scores, we employed the stochastic frontier analysis and our results show that cocoa farmers generally exhibited significant levels of technical, allocative, and economic inefficiencies. We estimated the average technical, allocative, and economic efficiencies scores among the cocoa farmers to be 67%, 69%, and 51% respectively. The analysis of the determinants of technical, allocative, and economic inefficiencies revealed that farmer and farm-specific variables such as sex, household size, educational level, years of farming experience, frequency of extension contact, quality of extension received, use of climate smart adaptation technologies, farm size, farm labour and access to credit facilities significantly explain cocoa farm level efficiencies. Accordingly, we recommend that extension service providers and COCOBOD develop strategies to improve upon the quality of extension service delivery as well as incorporate the promotion and adoption of climate smart adaptation technologies into its productivity enhancement programmes for farmers.
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- 2022
15. First record of Babesia and Theileria parasites in ticks from Kassena‐Nankana, Ghana.
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Addo, Seth Offei, Bentil, Ronald Essah, Baako, Bernice Olivia Ama, Addae, Charlotte Adwoa, Behene, Eric, Asoala, Victor, Mate, Suzanne, Oduro, Daniel, Dunford, James C., Larbi, John Asiedu, Baidoo, Philip Kweku, Wilson, Michael David, Diclaro, Joseph W., and Dadzie, Samuel K.
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BABESIA ,THEILERIA ,TICKS ,PARASITES ,TICK control ,LIVESTOCK productivity ,HYALOMMA - Abstract
Ticks are efficient vectors for transmitting pathogens that negatively affect livestock production and pose a risk to public health. In this study, Babesia and Theileria species were identified in ticks collected from cattle, sheep and goats from the Kassena‐Nankana Districts of Ghana between February and December 2020. A total of 1550 ticks were collected, morphologically identified, pooled and screened for pathogens using primers that amplify a 560 bp fragment of the ssrRNA gene and Sanger sequencing. Amblyomma variegatum (62.98%) was the predominant tick species. From the 491 tick pools screened, 12/15 (2.44%) positive pools were successfully sequenced. The pathogen DNA identified were Theileria ovis in eight (15.38%) pools of Rhipicephalus evertsi evertsi, Theileria velifera in two (0.78%) pools of A. variegatum and Babesia occultans and Babesia sp. Xinjiang in one (1.72%) pool each of Hyalomma truncatum. It was further observed that T. ovis occurred in ticks collected from only sheep (p < 0.001) which were females (p = 0.023) and < =1 year old (p = 0.040). This study reports the first identification of these pathogens in ticks within Kassena‐Nankana. With the constant trade of livestock, there is a need for effective tick control measures to prevent infection spread. [ABSTRACT FROM AUTHOR]
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- 2023
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16. Sustainability and competitive advantage from a developing economy
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Kwarteng, Amoako, Dadzie, Samuel Ato, and Famiyeh, Samuel
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- 2016
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17. Resistance to pirimiphos-methyl in West African Anopheles is spreading via duplication and introgression of the Ace1 locus
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Grau-Bové, Xavier, Lucas, Eric, Pipini, Dimitra, Rippon, Emily, van ‘t Hof, Arjèn E., Constant, Edi, Dadzie, Samuel, Egyir-Yawson, Alexander, Essandoh, John, Chabi, Joseph, Djogbénou, Luc, Harding, Nicholas J., Miles, Alistair, Kwiatkowski, Dominic, Donnelly, Martin J., Weetman, David, Jorge Edouardo Amaya-Romero, Diego, Ayala, Battey, C. J., Philip, Bejon, Besansky, Nora J., Austin, Burt, Jorge, Cano, Caputo, Beniamino, Edi, Constant, Carlo, Costantini, Boubacar, Coulibaly, DELLA TORRE, Alessandra, Abdoulaye, Diabate´, João, Dinis, Eleanor, Drury, Jorge, Edouardo, Nohal, Elissa, John, Essandoh, Fontaine, Michael C., Godfray, H. Charles J., Hahn, Matthew W., Christa, Henrichs, Christina, Hubbart, Isaacs, Alison T., Musa, Jawara, Jeffreys, Anna E., Dushyanth, Jyothi, Maryam, Kamali, Kern, Andrew D., Kwiatkowski, Dominic P., Clarkson, Chris S., Lawniczak, Mara K. N., Gilbert Le Goff, Lucas, Eric R., Cinzia, Malangone, Mawejje, Henry D., Charles, Mbogo, Daniel, Mead, Janet, Midega, Alistair, Miles, Nwakanma, Davis C., Samantha, O’Loughlin, João, Pinto, Riehle, Michelle M., Vincent, Robert, Rockett, Kirk A., Rohatgi, Kyanne R., Kate, Rowlands, Schrider, Daniel R., Igor, Sharakhov, Victoria, Simpson, Jim, Stalker, Troco, Arlete D., Vernick, Kenneth D., David, Weetman, White, Bradley J., Wilding, Craig S., IRTA, Institute of Molecular Biology and Biotechnology (IMBB-FORTH), Foundation for Research and Technology - Hellas (FORTH), Maladies infectieuses et vecteurs : écologie, génétique, évolution et contrôle (MIVEGEC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Centre de Recherche Entomologique de Cotonou (CREC), Ministère de la Santé, The Wellcome Trust Centre for Human Genetics [Oxford], University of Oxford [Oxford], Liverpool School of Tropical Medicine (LSTM), Instituto de Higiene e Medicina Tropical (IHMT), Global Health and Tropical Medicine (GHTM), Vector borne diseases and pathogens (VBD), Institut de Recerca i Tecnologia Agroalimentàries = Institute of Agrifood Research and Technology (IRTA), University of Oxford, and Fontaine lab
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Cancer Research ,Insecticides ,Heredity ,Introgression ,Anopheles gambiae ,Anopheles Gambiae ,QH426-470 ,Disease Vectors ,Mosquitoes ,Ghana ,Insecticide Resistance ,Geographical Locations ,пиримифос-метил ,0302 clinical medicine ,Medical Conditions ,[SDV.MHEP.MI]Life Sciences [q-bio]/Human health and pathology/Infectious diseases ,Invertebrate Genomics ,Medicine and Health Sciences ,Genetics(clinical) ,Copy-number variation ,Association mapping ,Genetics (clinical) ,SDG 15 - Life on Land ,Data Management ,Genetics ,0303 health sciences ,education.field_of_study ,biology ,malaria vectors ,genomics ,insecticide resistance ,anopheles gambiae ,anopheles coluzzii ,Anopheles ,Eukaryota ,Phylogenetic Analysis ,Agriculture ,Genomics ,3. Good health ,Insects ,Phylogenetics ,Africa, Western ,Genetic Mapping ,Infectious Diseases ,[SDE]Environmental Sciences ,Acetylcholinesterase ,Agrochemicals ,Research Article ,Computer and Information Sciences ,африканские комары ,Evolutionary Processes ,DNA Copy Number Variations ,Arthropoda ,030231 tropical medicine ,Population ,Locus (genetics) ,Mosquito Vectors ,Genetic Introgression ,03 medical and health sciences ,SDG 3 - Good Health and Well-being ,Genes, Duplicate ,Animals ,Humans ,Evolutionary Systematics ,education ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,030304 developmental biology ,Taxonomy ,Evolutionary Biology ,Haplotype ,Organisms ,Biology and Life Sciences ,Organothiophosphorus Compounds ,biology.organism_classification ,Invertebrates ,Malaria ,Insect Vectors ,Species Interactions ,Haplotypes ,Animal Genomics ,Vector (epidemiology) ,People and Places ,Africa ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology ,Zoology ,Entomology - Abstract
Vector population control using insecticides is a key element of current strategies to prevent malaria transmission in Africa. The introduction of effective insecticides, such as the organophosphate pirimiphos-methyl, is essential to overcome the recurrent emergence of resistance driven by the highly diverse Anopheles genomes. Here, we use a population genomic approach to investigate the basis of pirimiphos-methyl resistance in the major malaria vectors Anopheles gambiae and A. coluzzii. A combination of copy number variation and a single non-synonymous substitution in the acetylcholinesterase gene, Ace1, provides the key resistance diagnostic in an A. coluzzii population from Côte d’Ivoire that we used for sequence-based association mapping, with replication in other West African populations. The Ace1 substitution and duplications occur on a unique resistance haplotype that evolved in A. gambiae and introgressed into A. coluzzii, and is now common in West Africa primarily due to selection imposed by other organophosphate or carbamate insecticides. Our findings highlight the predictive value of this complex resistance haplotype for phenotypic resistance and clarify its evolutionary history, providing tools to for molecular surveillance of the current and future effectiveness of pirimiphos-methyl based interventions., Author summary Control of mosquito populations via insecticidal tools or interventions is a mainstay of campaigns to reduce malaria transmission. However, especially in sub-Saharan Africa, continued insecticidal selection pressure on the most important species of Anopheles malaria mosquitoes has favoured the evolutionary selection of increasingly effective resistance mechanisms. We investigate the genetic basis of resistance to the organophosphate pirimiphos-methyl, the dominant insecticide now used for indoor residual spraying campaigns in Africa. Genome-wide association analysis of a population from Cote d’Ivoire showed that resistant specimens share a unique combination of mutations in one gene, the acetylcholinesterase enzyme, which constitute the prime cause of pirimiphos-methyl resistance. Further testing of these mutations in diagnostic assays involving two major malaria vectors, A. coluzzii and A. gambiae, validate their use as informative predictors of pirimiphos-methyl resistance. Using data from a large collection of whole genome sequenced specimens from a broader range of locations (Burkina-Faso, Côte d’Ivoire, Ghana, and Guinea), our evolutionary analyses demonstrate that these mutations emerged in A. gambiae and transferred into A. coluzzii by inter-specific hybridisation. Our results show how resistance mechanisms in key malaria vectors have developed and spread, and provide validated tools for molecular surveillance to inform public health campaigns.
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- 2021
18. Promoting Improved Agricultural Technologies to Increase Smallholder Farm Production Efficiency: Ghanaian Study of Cassava Farmers
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Inkoom, Emmanuel Wisgtos, Dadzie, Samuel Kwesi Ndzebah, and Ndebugri, Joseph
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Productivity Analysis ,Production Economics ,Agricultural and Food Policy ,Community/Rural/Urban Development ,Farm Management ,Average treatment effect model ,cassava farmers ,Agribusiness ,technical efficiency ,technology adoption ,Crop Production/Industries ,Ghana - Abstract
Our study provides empirical answer that verifies increase in productivity, if any, through promotion of improved agricultural technologies among smallholder food crop farmers in Africa. We specifically examined Root and Tuber Improvement and Marketing Programme (RTIMP) technology effect on improving the production efficiency of cassava farmers in Ghana. we stratified RTIMP cassava farmers into above average adopters and below average adopters based on their adoption intensity scores and further examined differences in their efficiency levels which we estimated by employing the stochastic frontier production model (SFA). In order to empirically establish if RTIMP technology has actually had effect in improving productivity of the cassava farmers, we estimated an adjusted regression model (average treatment effect and average treatment effect on the treated models). Our results show that the potential outcome mean technical efficiency of about 69% achieved by the above average RTIMP technology adopters is significantly higher than that of the below average technology adopters which was found to be about 64%. Our Average Treatment Effect on the Treated (ATET) estimates confirm that there has been significant increase in the technical efficiency of cassava farmers attributable to the adoption of the RTIMP cassava technology.
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- 2020
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19. Studies on the Feeding Behaviour of Larvae of the Predaceous Mosquito Culex (Lutzia) tigripes Grandpre and Chamoy (Diptera: Culicidae)
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Appawu, Maxwell A., Dadzie, Samuel K., and Quartey, Solomon Q.
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- 2000
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20. A review and evaluation of market orientation research in an emerging African economy.
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Coffie, Stanley, Blankson, Charles, and Dadzie, Samuel Ato
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MARKET orientation ,MARKETING research ,BANKING industry ,THEORY-practice relationship - Abstract
The paper synthesizes the level of strategic market orientation of firms operating in the emerging economy of Ghana over the last two decades. It dwells on market orientation studies in general, and the banking industry and exporting firms in particular. Market orientation has a positive relationship with performance for both foreign and domestic firms across the many studies. Foreign firms in general appear more market oriented due to experience effect and relationship with parent organizations. As competition heats up in the banking industry, organizations need to be more innovative to sustain their performance or to survive. For exporting firms, there is the need for decreased formalization and increased decentralization so as to enhance the levels of market orientation. The paper develops propositions to guide organizations in applying marketing principles in the running of their business activities. Further, the paper provides an update on the literature with suggestions for future research in the theory and practice of strategic market orientation in the context of the study. [ABSTRACT FROM AUTHOR]
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- 2020
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21. Risk of transmission of viral haemorrhagic fevers and the insecticide susceptibilitystatus of aedes aegypti (linnaeus) in some sites in Accra, Ghana
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Suzuki, Takashi, Osei, Joseph H, Sasaki, Akihiro, Adimazoya, Michelle, Appawu, Maxwell, Boakye, Daniel, Ohta, Nobuo, and Dadzie, Samuel
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Male ,Insecticides ,Hemorrhagic Fevers, Viral ,Drug Resistance ,Mosquito Vectors ,Ghana ,Risk Assessment ,DDT ,Disease Outbreaks ,Aedes ,Larva ,Nitriles ,Pyrethrins ,Animals ,Humans ,Original Article ,Female ,Permethrin - Abstract
Dengue is one of the emerging diseases that can mostly only be controlled by vector control since there is no vaccine for the disease. Although, Dengue has not been reported in Ghana, movement of people from neighbouring countries where the disease has been reported can facilitate transmission of the disease.This study was carried on the University of Ghana campus to determine the risk of transmission of viral haemorrhagic fevers and the insecticide susceptibility status ofLarval surveys were carried to inspect containers within households and estimate larval indices and adultThe survey results indicated that the density ofThis study was supported in part by Japan Initiative for Global Research Network on Infectious Diseases (J-Grid).
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- 2016
22. Molecular detection of dengue virus in patients suspected of Ebola virus disease in Ghana.
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Bonney, Joseph Humphrey Kofi, Hayashi, Takaya, Dadzie, Samuel, Agbosu, Esinam, Pratt, Deborah, Nyarko, Stephen, Asiedu-Bekoe, Franklin, Ido, Eiji, Sarkodie, Badu, Ohta, Nobuo, and Yamaoka, Shoji
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DENGUE viruses ,EBOLA virus disease ,PUBLIC health ,SEROTYPES - Abstract
Dengue fever is known to be one of the most common arthropod-borne viral infectious diseases of public health importance. The disease is now endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, Southeast Asia and the Western Pacific with an estimated two fifths of the world's population being at risk. The notable endemic viral hemorrhagic fevers (VHFs) found in West Africa, including yellow fever, Lassa fever, Rift Valley fever, dengue fever and until recently Ebola have been responsible for most outbreaks with fatal consequences. These VHFs usually produce unclear acute febrile illness, especially in the acute phase of infection. In this study we detected the presence of 2 different serotypes (DENV-2 and DENV-3) of Dengue virus in 4 sera of 150 patients clinically suspected of Ebola virus disease during the Ebola Virus Disease (EVD) outbreak in West Africa with the use of serological and molecular test assays. Sequence data was successfully generated for DENV-3 and phylogenetic analysis of the envelope gene showed that the DENV-3 sequences had close homology with DENV-3 sequences from Senegal and India. This study documents molecular evidence of an indigenous Dengue fever viral infection in Ghana and therefore necessitates the need to have an efficient surveillance system to rapidly detect and control the dissemination of the different serotypes in the population which has the potential to cause outbreaks of dengue hemorrhagic fevers. [ABSTRACT FROM AUTHOR]
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- 2018
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23. Institutional dimensions and conflict resolution strategy in international joint ventures: An empirical examination.
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Kwarteng, Amoako, Dadzie, Samuel Ato, Famiyeh, Samuel, and Aklamanu, Alphones Mawusi Kwasi
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CONFLICT management ,CULTURE conflict ,INSTITUTIONS (Philosophy) ,JOINT ventures - Abstract
This study examines the impact of the host‐country institutional structures on the choice of conflict resolution strategy in the international joint venture (IJV). Using the survey method and relying on multiple regression, we demonstrate that there is a statistically significant relationship between institutional pillars and the choice of conflict resolution strategy in the international joint venture in the context of Ghana. In particular, we demonstrate that legalistic and forcing conflict resolution strategies are influenced by the regulative institutional pillar, while compromising and problem‐solving conflict resolution strategies are impacted by normative and cognitive institutional pillars. The multigrouping analysis results show that the views and the choice of foreign partners on conflict resolution strategy differ from that of the local partners to the IJV. This study fills the gap by empirically testing the conflict resolution strategies of firms in relation to the role of regulative, normative, and cognitive institutional pillars of the host country. [ABSTRACT FROM AUTHOR]
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- 2018
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24. Do Strategic Motives Affect Ownership Mode of Foreign Direct Investments (FDIs) in Emerging African Markets? Evidence from Ghana.
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Dadzie, Samuel Ato, Owusu, Richard Afriyie, Amoako, Kwarteng, and Aklamanu, Alphonse
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FOREIGN investments ,FOREIGN subsidiaries ,INTERNATIONAL business enterprises ,LOGISTIC regression analysis ,JOINT ventures - Abstract
The objective of this study is to examine the influence of ownership, location, and internalization‐specific factors, as well as strategic motives on ownership choice of foreign subsidiaries in Ghana. The authors use a quantitative methodology in order to statistically explore the relationships between dependent and independent variables by using the logistic regression model. The analysis was based on 115 manufacturing investments made by multinational corporations (MNCs) from different countries in 1994–2013. The results indicate that contractual risk leads to the choice of whollymowned subsidiary while cultural distance and country risk lead to the choice of the joint venture. In the case of the motives, efficiency‐seeking and resource‐seeking FDIs lead to the choice of the joint venture. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]
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- 2018
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25. Detection of a novel putative phlebovirus and first isolation of Dugbe virus from ticks in Accra, Ghana.
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Kobayashi, Daisuke, Ohashi, Mitsuko, Osei, Joseph H.N., Agbosu, Esinam, Opoku, Millicent, Agbekudzi, Alfred, Joannides, Joannitta, Fujita, Ryosuke, Sasaki, Toshinori, Bonney, J.H. Kofi, Dadzie, Samuel, Isawa, Haruhiko, Sawabe, Kyoko, and Ohta, Nobuo
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Ticks are ectoparasites that transmit various types of human and animal pathogens. In particular, emerging and re-emerging diseases caused by tick-borne viruses are public health concerns around the world. However, in many countries of the sub-Saharan African region, epidemiological information on tick-borne viral infections is limited, and their prevalence and distribution remain largely unknown. In this study, we conducted surveillance on ticks to detect medically important tick-borne bunyaviruses in three study sites in and near to Accra, the capital city of Ghana, in 2015. Domestic dogs and cattle were surveyed and were found to be infested with various tick species belonging to the genera Rhipicephalus , Amblyomma and Haemaphysalis . Importantly, we detected a novel putative phlebovirus in Rhipicephalus ticks, and successfully isolated a new strain of Dugbe virus from Am. variegatum ticks. To our knowledge, this is the first report of tick-associated viruses in Ghana other than Crimean-Congo hemorrhagic fever virus. [ABSTRACT FROM AUTHOR]
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- 2017
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26. Risk of transmission of viral haemorrhagic fevers and the insecticide susceptibility status of aedes aegypti (linnaeus) in some sites in Accra, Ghana.
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Takashi Suzuki, Osei, Joseph H., Akihiro Sasaki, Adimazoya, Michelle, Appawu, Maxwell, Boakye, Daniel, Nobuo Ohta, and Dadzie, Samuel
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DENGUE ,HEMORRHAGIC fever ,PUBLIC health ,AEDES aegypti ,DELTAMETHRIN ,PREVENTION ,INFECTIOUS disease transmission ,DISEASE risk factors - Abstract
Background: Dengue is one of the emerging diseases that can mostly only be controlled by vector control since there is no vaccine for the disease. Although, Dengue has not been reported in Ghana, movement of people from neighbouring countries where the disease has been reported can facilitate transmission of the disease. Objective: This study was carried on the University of Ghana campus to determine the risk of transmission of viral haemorrhagic fevers and the insecticide susceptibility status of Ae. aegypti in some sites in Accra, Ghana. Design: Larval surveys were carried to inspect containers within households and estimate larval indices and adult Aedes mosquitoes were collected using human landing collection technique. WHO tube assays was used to assess the insecticide susceptibility status of Aedes mosquitoes. Results: Ae. aegypti were the most prevalent species, 75.5% and followed by Ae. vittatus, 23.9 %. Ae. albopictus and Ae. granti were in smaller numbers. Household index (HI), Breteau index (BI), and container index were calculated as 8.2%, 11.2% and 10.3% respectively with man-vector contact rate of 0.67 bites/man-hour estimated for the area. The mortalities recorded for Ae. aegypti from WHO tube assays was 88%, 94%, 80% and 99% for DDT (4%), deltamethrin (0.05%), lambdacyhalothrin (0.05%) and permethrin (0.75%) respectively. Conclusion: The survey results indicated that the density of Aedes mosquitoes was considered to be sufficient to promote an outbreak of viral haemorrhagic fevers on Legon Campus. Aedes mosquitoes were found to be resistant to DDT, deltamethrin and lamdacyhalothrin, but susceptible to permethrin. [ABSTRACT FROM AUTHOR]
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- 2016
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27. Discovery of Point Mutations in the Voltage-Gated Sodium Channel from African Aedes aegypti Populations: Potential Phylogenetic Reasons for Gene Introgression.
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Kawada, Hitoshi, Higa, Yukiko, Futami, Kyoko, Muranami, Yuto, Kawashima, Emiko, Osei, Joseph H. N., Sakyi, Kojo Yirenkyi, Dadzie, Samuel, de Souza, Dziedzom K., Appawu, Maxwell, Ohta, Nobuo, Suzuki, Takashi, and Minakawa, Noboru
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YELLOW fever ,SODIUM channels ,AEDES ,FLAVIVIRAL diseases ,ALKALI metals - Abstract
Background: Yellow fever is endemic in some countries in Africa, and Aedes aegpyti is one of the most important vectors implicated in the outbreak. The mapping of the nation-wide distribution and the detection of insecticide resistance of vector mosquitoes will provide the beneficial information for forecasting of dengue and yellow fever outbreaks and effective control measures. Methodology/Principal Findings: High resistance to DDT was observed in all mosquito colonies collected in Ghana. The resistance and the possible existence of resistance or tolerance to permethrin were suspected in some colonies. High frequencies of point mutations at the voltage-gated sodium channel (F1534C) and one heterozygote of the other mutation (V1016I) were detected, and this is the first detection on the African continent. The frequency of F1534C allele and the ratio of F1534C homozygotes in Ae. aegypti aegypti (Aaa) were significantly higher than those in Ae. aegypti formosus (Aaf). We could detect the two types of introns between exon 20 and 21, and the F1534C mutations were strongly linked with one type of intron, which was commonly found in South East Asian and South and Central American countries, suggesting the possibility that this mutation was introduced from other continents or convergently selected after the introgression of Aaa genes from the above area. Conclusions/Significance: The worldwide eradication programs in 1940s and 1950s might have caused high selection pressure on the mosquito populations and expanded the distribution of insecticide-resistant Ae. aegypti populations. Selection of the F1534C point mutation could be hypothesized to have taken place during this period. The selection of the resistant population of Ae. aegypti with the point mutation of F1534C, and the worldwide transportation of vector mosquitoes in accordance with human activity such as trading of used tires, might result in the widespread distribution of F1534C point mutation in tropical countries. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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28. Characteristics of asymptomatic Plasmodium spp. parasitaemia in Kwahu-Mpraeso, a malaria endemic mountainous district in Ghana, West Africa.
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Owusu, Ewurama D. A., Buabeng, Vincent, Dadzie, Samuel, Brown, Charles A., Grobusch, Martin P., and Mens, Petra
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MALARIA ,PLASMODIUM ,TRANSMISSION of protozoan diseases ,SPOROZOITES ,UNIVARIATE analysis ,MULTIVARIATE analysis - Abstract
Background: Malaria control efforts in Ghana have reduced the countrywide average malaria prevalence from 71 % in 2000 to about 51 % in 2012; however, its main focus is on symptomatic malaria. If further progress is to be made, parasite reservoirs in asymptomatic carriers need to be moved into focus. This study profiles asymptomatic Plasmodium spp. parasitaemia amongst residents of mountainous Kwahu-Mpraeso in the Eastern region of Ghana. Methods: A cross-sectional study of 360 residents was carried out from October to December 2013. This included recording demographics, malaria testing of asymptomatic residents, and gathering of their malaria history. Assessment of malaria transmission was done with molecular identification of vectors, determination of sporozoite rate, insecticide resistance status and biting pattern. Univariate and multivariate analysis were used to establish risk determinants. Results: In Mpraeso, in the Kwahu highland of Eastern Region, children were at higher risk of asymptomatic parasitaemia, thereby contributing to the parasite reservoir and hence sustained malaria transmission. As well, findings suggested Hb AC genotype influenced susceptibility to asymptomatic malaria with 8.03-fold increase in odds (univariate) and 11.92-fold higher odds (multivariate) than the normal Hb AA. The mosquito vector predominant in the area was Anopheles gambiae sensu stricto of the homozygous pyrethroid resistant form (RR); with biting mainly occurring indoors. Conclusion: For an effective malaria control in this area, interventions should be formulated and implemented to target asymptomatic parasite reservoirs; especially in children and people with Hb AC. The dominant vector species An. gambiae s.s. and its feeding patterns of biting indoors should also be considered. [ABSTRACT FROM AUTHOR]
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- 2016
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29. Transmission indices and microfilariae prevalence in human population prior to mass drug administration with ivermectin and albendazole in the Gomoa District of Ghana.
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Aboagye-Antwi, Fred, Kwansa-Bentum, Bethel, Dadzie, Samuel K., Ahorlu, Collins K., Appawu, Maxwell A., Gyapong, John, Wilson, Michael David, and Boakye, Daniel Adjei
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DRUG administration ,IVERMECTIN ,ALBENDAZOLE ,FILARIASIS ,COMMUNITY involvement ,CULEX - Abstract
Background: The Lymphatic Filariasis Elimination Programme in Ghana involves annual mass drug administration (MDA) of ivermectin and albendazole to persons living in endemic areas. This is repeated annually for 4-6 years to span across the reproductive lifespan of adult worms. In order to stimulate participation of community members in the MDA programme, this study was carried out to understand local views on transmission, management and prevention of the disease. The study also presents baseline transmission indices and microfilariae prevalence in the human population in eight endemic communities of coastal Ghana prior to the MDA. Methods: A descriptive survey was carried out to explore perceptions on causes, treatment and prevention of lymphatic filariasis. Perceptions on community participation in disease control programmes were also assessed. After participants were selected by cluster sampling and 100 μl of blood sampled from each individual and examined for mf microfilariae. A similar volume of blood was used to determine the presence of circulating filarial antigen. Mosquitoes were collected simultaneously at all sites by human landing catches for 4 days per month over a six-month period. All Anopheles mosquitoes were dissected and examined for the larval stages of the parasite following which molecular identification of both vector and parasite was done. Results: Eight hundred and four persons were interviewed, of which 284 (32.9 %; CI 31.1-34.5) acknowledged elephantiasis and hydrocoele as health related issues in the communities. Thirty-three people (3.8 %; CI 2.1-5.5) thought sleeping under bed net could help prevent elephantiasis. Microfilariae prevalence was 4.6 % (43/941) whiles 8.7 % (75/861) were positive for circulating filarial antigen. A total of 17,784 mosquitoes were collected, majority (55.8 %) of which were Anopheles followed by Culex species (40 %). Monthly biting rates ranged between 311 and 6116 bites/person for all the eight communities together. Annual transmission potential values for An. gambiae s.s. and An. funestus were 311.35 and 153.50 respectively. Conclusion: Even though the highest mf density among inhabitants was recorded in a community that had the lowest Anopheles density with Culex species constituting 95 % of all mosquitoes collected, Anopheles gambiae s.s. and An. funestus remained the main vectors. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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30. Understanding establishment mode choice of foreign manufacturing firms in Ghana.
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Dadzie, Samuel Ato and Owusu, Richard Afriyie
- Abstract
Purpose – The purpose of this paper is to analyse the foreign direct investment (FDI) strategies of manufacturing firms in Ghana using the eclectic model in order to understand how ownership, location and internalization factors impact FDI to developing countries like Ghana. Design/methodology/approach – The authors use a quantitative methodology in order to statistically explore the relationships between dependent and independent variables. The data comes from a sample of 75 multinational enterprises that invested in the manufacturing sector between 1994 and 2008. Findings – The results reveal that large firm size, extensive international experience and large market size lead to the choice of acquisition mode of entry, while high cultural distance, high country risk, high proprietary assets and incentives lead to the choice of greenfield mode in the context of Ghana. Research limitations/implications – The results imply that the different economic, business and legal (locational) conditions of developing countries create different FDI strategies and paths of companies compared to developed markets. Practical implications – Policy makers in developing countries should make efforts to improve market size, the institutional and regulatory environment, as well as the availability of human capital in order to attract FDI. Originality/value – FDI studies have mainly analysed establishment mode strategies of firms in advanced markets. There is an increasing amount of research on FDI in emerging markets but very little on developing countries and African markets. Therefore, this study enables the authors to develop implications for existing theory and generate practical implications for firms and policy makers related to African and developing country markets. [ABSTRACT FROM AUTHOR]
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- 2015
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31. Foreign Subsidiary Performance: Evidence from Ghana.
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Dadzie, Samuel, Larimo, Jorma, and Nguyen, HuuLe
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FOREIGN subsidiaries , *ORGANIZATIONAL performance , *JOINT ventures - Abstract
The objective of this study is to examine the influence of selected ownership, location, and internalization-specific factors on performance of foreign subsidiaries in Ghana. Our analysis was based on 75 manufacturing investments made by MNEs from different countries in 1994–2008. The results indicated that market size, host country experience, greenfield establishment mode, and joint venture ownership mode had positively impacted performance of foreign subsidiaries independent of the measure of performance. Furthermore, international experience and cultural distance had influenced performance when the total performance measure was used. Finally, the ownership mode significantly influenced performance only in greenfield investments, and not in acquisition mode. [ABSTRACT FROM AUTHOR]
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- 2014
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32. Role of species composition in malaria transmission by the Anopheles funestus group (Diptera: Culicidae) in Ghana.
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Dadzie, Samuel K., Brenyah, Ruth, and Appawu, Maxwell A.
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Malaria remains a public health problem in Ghana, with Anopheles gambiae and Anopheles funestus as the predominant vectors. While much information exists on the species composition of An. gambiae, very little exists for An. funestus. his study was carried out to determine the species composition of An. funestus Giles populations from three ecological areas in Ghana and investigate their role in malaria transmission. Mosquitoes were collected using human landing and pyrethrum spray methods. A total of 10,254 Anopheles individuals were collected, out of which An. funestus constituted 53.6% (5,496). An. funestus sensu stricto (s.s.) and Anopheles lessoni were identiied as the only members of the An. funestus group in all three ecological areas. All 62 sporozoite positive specimens that were identiied as An. funestus s.s. were highly anthropophilic with a human blood index in the range of 80-96%, whereas more than 83% of the An. leesoni had fed on either bovine, goat, or sheep. Malaria transmission was higher in the Sahel savannah area than the rest of the ecological zones, with An. funestus s.s. being implicated as a vector of malaria in all ecological zones. Anopheles leesoni occurred in all the ecological areas but played no role in malaria transmission. he study established the importance of An. funestus s.s. in malaria transmission in Ghana. [ABSTRACT FROM AUTHOR]
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- 2013
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33. Lymphatic filariasis in Ghana: establishing the potential for an urban cycle of transmission.
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Gbakima, Aiah A., Appawu, Maxwell A., Dadzie, Samuel, Karikari, Collins, Sackey, Samuel O., Baffoe-Wilmot, Aba, Gyapong, Johnny, and Scott, Alan L.
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FILARIASIS ,HELMINTHIASIS ,PARASITIC diseases ,MEDICAL helminthology ,INFECTIOUS disease transmission ,URBANIZATION ,PUBLIC health - Abstract
Lymphatic filariasis is a significant public health and economic problem in many tropical and sub-tropical regions. Unplanned urbanization leading to a lack of proper sanitary conditions has resulted in an increase in the urban-based transmission of a number of vector-borne diseases, including lymphatic filariasis. It has been well established that lymphatic filariasis is endemic in rural areas of Ghana. The goal of this study was to determine if there is a potential of establishing urban transmission cycles in Ghana's major cities. We clinically and immunologically assessed 625 individuals from the three major urban areas (Bawku, Bolgatanga and Secondi/Takoradi), finding that the prevalence of infection withWuchereria bancroftiranged from 0 to 12.5%. The results of a polymerase chain reaction based analysis of mosquitoes collected from these areas suggested that there is a low but detectable prevalence of mosquitoes infected withW. bancrofti. We conclude that there may be a potential for an established urban transmission of lymphatic filariasis in Ghana. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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34. Lymphatic filariasis in Ghana: entomological investigation of transmission dynamics and intensity in communities served by irrigation systems in the Upper East Region of Ghana.
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Appawu, Maxwell A., Dadzie, Samuel K., Baffoe-Wilmot, Aba, Wilson, Michael D., Appawu, M A, Dadzie, S K, Baffoe-Wilmot, A, and Wilson, M D
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- *
IRRIGATION , *FILARIASIS , *INFECTIOUS disease transmission - Abstract
We conducted an entomological study to document the effect of irrigation on the vectors and transmission dynamics of lymphatic filariasis in the Upper East Region of Ghana. Mosquitoes were collected by indoor spraying of houses in a cluster of communities located around irrigation projects (Tono and Vea) and others without reservoirs (Azoka). Anopheles gambiae s.s. was the dominant species and major vector, followed by An. funestus. Anopheles arabiensis constituted 9--14% of the An. gambiae complex but none were infective. Culex quinquefasciatus was also not infective in these communities. Chromosomal examinations showed that >60% (n=280--386) of the An. gambiae s.s. in irrigated communities were Mopti forms whilst 73% (n=224) in the non-irrigated area were Savannah forms. Infectivity rates (2.3--2.8 vs. 0.25), worm load (1.62--2.04 vs. 1.0), annual bites per person (6.50--8.83 vs. 0.47) and annual transmission potential (13.26--14.30 vs. 0.47) were significantly higher in irrigated communities. [ABSTRACT FROM AUTHOR]
- Published
- 2001
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35. Entomological Assessment of the Status and Risk of Mosquito-borne Arboviral Transmission in Ghana.
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Amoa-Bosompem, Michael, Kobayashi, Daisuke, Murota, Katsunori, Faizah, Astri Nur, Itokawa, Kentaro, Fujita, Ryosuke, Osei, Joseph Harold Nyarko, Agbosu, Esinam, Pratt, Deborah, Kimura, Shohei, Kwofie, Kofi Dadzie, Ohashi, Mitsuko, Bonney, Joseph H. Kofi, Dadzie, Samuel, Sasaki, Toshinori, Ohta, Nobuo, Isawa, Haruhiko, Sawabe, Kyoko, and Iwanaga, Shiroh
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ARBOVIRUSES ,AEDES aegypti ,RISK assessment ,VIRUS isolation ,DOUBLE-stranded RNA ,RNA viruses ,ARBOVIRUS diseases ,MOSQUITO control - Abstract
Entomological surveillance is one of the tools used in monitoring and controlling vector-borne diseases. However, the use of entomological surveillance for arboviral infection vector control is often dependent on finding infected individuals. Although this method may suffice in highly endemic areas, it is not as effective in controlling the spread of diseases in low endemic and non-endemic areas. In this study, we examined the efficiency of using entomological markers to assess the status and risk of arbovirus infection in Ghana, which is considered a non-endemic country, by combining mosquito surveillance with virus isolation and detection. This study reports the presence of cryptic species of mosquitoes in Ghana, demonstrating the need to combine morphological identification and molecular techniques in mosquito surveillance. Furthermore, although no medically important viruses were detected, the importance of insect-specific viruses in understanding virus evolution and arbovirus transmission is discussed. This study reports the first mutualistic relationship between dengue virus and the double-stranded RNA Aedes aegypti totivirus. Finally, this study discusses the complexity of the virome of Aedes and Culex mosquitoes and its implication for arbovirus transmission. [ABSTRACT FROM AUTHOR]
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- 2020
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36. The Role of Detoxification Enzymes in the Adaptation of the Major Malaria Vector Anopheles gambiae (Giles; Diptera: Culicidae) to Polluted Water
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King, Sandra A., Onayifeke, Bibian, Akorli, Jewelna, Sibomana, Isaie, Chabi, Joseph, Manful-Gwira, Theresa, Dadzie, Samuel, Suzuki, Takashi, Wilson, Michael D., Boakye, Daniel A., and Souza, Dziedzom K. de
- Published
- 2017
- Full Text
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