5 results on '"Osei-Atweneboana, Mike Y."'
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2. Onchocerciasis transmission in Ghana: biting and parous rates of host-seeking sibling species of the Simulium damnosum complex
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Lamberton, Poppy H. L., Cheke, Robert A., Walker, Martin, Winskill, Peter, Osei-Atweneboana, Mike Y., Tirados, Iñaki, Tetteh-Kumah, Anthony, Boakye, Daniel A., Wilson, Michael D., Post, Rory J., and Basáñez, María-Gloria
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S. damnosum s.s ,Adult ,Male ,S. yahense ,Adolescent ,S. squamosum form C ,S. squamosum form E ,Onchocerciasis ,Ghana ,Young Adult ,S. sanctipauli ,Species Specificity ,Animals ,Humans ,Simuliidae ,QL ,Research ,Simulium damnosum s.l ,Beffa form of S. soubrense ,Parous rate ,Insect Bites and Stings ,S. sirbanum ,Feeding Behavior ,Middle Aged ,R1 ,Insect Vectors ,Biting rate ,Onchocerca volvulus ,Infectious Diseases ,Host-seeking behaviour ,Parasitology ,Cattle ,Female ,RB ,RA - Abstract
Background Ghana is renowned for its sibling species diversity of the Simulium damnosum complex, vectors of Onchocerca volvulus. Detailed entomological knowledge becomes a priority as onchocerciasis control policy has shifted from morbidity reduction to elimination of infection. To date, understanding of transmission dynamics of O. volvulus has been mainly based on S. damnosum sensu stricto (s.s.) data. We aim to elucidate bionomic features of vector species of importance for onchocerciasis elimination efforts. Methods We collected S. damnosum sensu lato from seven villages in four Ghanaian regions between 2009 and 2011, using standard vector collection, and human- and cattle-baited tents. Taxa were identified using morphological and molecular techniques. Monthly biting rates (MBR), parous rates and monthly parous biting rates (MPBR) are reported by locality, season, trapping method and hour of collection for each species. Results S. damnosum s.s./S. sirbanum were collected at Asubende and Agborlekame, both savannah villages. A range of species was caught in the Volta region (forest-savannah mosaic) and Gyankobaa (forest), with S. squamosum or S. sanctipauli being the predominant species, respectively. In Bosomase (southern forest region) only S. sanctipauli was collected in the 2009 wet season, but in the 2010 dry season S. yahense was also caught. MBRs ranged from 714 bites/person/month at Agborlekame (100% S. damnosum s.s./S. sirbanum) to 8,586 bites/person/month at Pillar 83/Djodji (98.5% S. squamosum). MBRs were higher in the wet season. In contrast, parous rates were higher in the dry season (41.8% vs. 18.4%), resulting in higher MPBRs in the dry season. Daily host-seeking activity of S. damnosum s.s./S. sirbanum was bimodal, whilst S. squamosum and S. sanctipauli had unimodal afternoon peaks. Conclusions The bionomic differences between sibling species of the S. damnosum complex need to be taken into account when designing entomological monitoring protocols for interventions and parameterising mathematical models for onchocerciasis control and elimination. Electronic supplementary material The online version of this article (doi:10.1186/s13071-014-0511-9) contains supplementary material, which is available to authorized users.
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- 2014
3. Genome-wide analysis of ivermectin response by Onchocerca volvulus reveals that genetic drift and soft selective sweeps contribute to loss of drug sensitivity.
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Doyle, Stephen R., Bourguinat, Catherine, Nana-Djeunga, Hugues C., Kengne-Ouafo, Jonas A., Pion, Sébastien D. S., Bopda, Jean, Kamgno, Joseph, Wanji, Samuel, Che, Hua, Kuesel, Annette C., Walker, Martin, Basáñez, Maria-Gloria, Boakye, Daniel A., Osei-Atweneboana, Mike Y., Boussinesq, Michel, Prichard, Roger K., and Grant, Warwick N.
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IVERMECTIN ,ONCHOCERCA volvulus ,GENETIC drift ,POPULATION genetics ,GENOMES - Abstract
Background: Treatment of onchocerciasis using mass ivermectin administration has reduced morbidity and transmission throughout Africa and Central/South America. Mass drug administration is likely to exert selection pressure on parasites, and phenotypic and genetic changes in several Onchocerca volvulus populations from Cameroon and Ghana—exposed to more than a decade of regular ivermectin treatment—have raised concern that sub-optimal responses to ivermectin's anti-fecundity effect are becoming more frequent and may spread. Methodology/Principal findings: Pooled next generation sequencing (Pool-seq) was used to characterise genetic diversity within and between 108 adult female worms differing in ivermectin treatment history and response. Genome-wide analyses revealed genetic variation that significantly differentiated good responder (GR) and sub-optimal responder (SOR) parasites. These variants were not randomly distributed but clustered in ~31 quantitative trait loci (QTLs), with little overlap in putative QTL position and gene content between the two countries. Published candidate ivermectin SOR genes were largely absent in these regions; QTLs differentiating GR and SOR worms were enriched for genes in molecular pathways associated with neurotransmission, development, and stress responses. Finally, single worm genotyping demonstrated that geographic isolation and genetic change over time (in the presence of drug exposure) had a significantly greater role in shaping genetic diversity than the evolution of SOR. Conclusions/Significance: This study is one of the first genome-wide association analyses in a parasitic nematode, and provides insight into the genomics of ivermectin response and population structure of O. volvulus. We argue that ivermectin response is a polygenically-determined quantitative trait (QT) whereby identical or related molecular pathways but not necessarily individual genes are likely to determine the extent of ivermectin response in different parasite populations. Furthermore, we propose that genetic drift rather than genetic selection of SOR is the underlying driver of population differentiation, which has significant implications for the emergence and potential spread of SOR within and between these parasite populations. [ABSTRACT FROM AUTHOR]
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- 2017
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4. Stability and change in the distribution of cytospecies of the Simulium damnosum complex (Diptera: Simuliidae) in southern Ghana from 1971 to 2011.
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Post, Rory J., Cheke, Robert A., Boakye, Daniel A., Wilson, Michael D., Osei-Atweneboana, Mike Y., Tetteh-Kumah, Anthony, Lamberton, Poppy H. L., Lee Crainey, J., Yaméogo, Laurent, and Basáñez, María-Gloria
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ONCHOCERCIASIS ,SIMULIUM damnosum ,GIANT chromosomes ,POPULATION biology ,GLOBAL environmental change - Abstract
Background: Simulium damnosum s.l., the most important vector of onchocerciasis in Africa, is a complex of sibling species that have been described on the basis of differences in their larval polytene chromosomes. These (cyto) species differ in their geographical distributions, ecologies and epidemiological roles. In Ghana, distributional changes have been recorded as a consequence of vector control and environmental change (e.g. deforestation), with potential disease consequences. We review the distribution of cytospecies in southern Ghana and report changes observed with reference to historical data collated from 1971 to 2005 and new identifications made between 2006 and 2011. Methods/Results: Larvae were collected from riverine breeding sites, fixed in Carnoy's solution and chromosome preparations made. Cytotaxonomic identifications from 1,232 samples (including 49 new samples) were analysed. We report long-term stability in cytospecies distribution in the rivers Afram, Akrum, Pawnpawn and Pru. For the rivers Oda, Ofin and Tano we describe (for the first time) patterns of distribution. We could not detect cytospecies composition changes in the upper Pra, and the lower Pra seems to have been stable. The elimination of the Djodji form of S. sanctipauli in the Volta Region seems to have had no long-term effects on the distribution of the other cytospecies, despite an initial surge by S. yahense. There has been a recent increase in the occurrence of savannah cytospecies in the river Asukawkaw, and this might be related to continuing deforestation. Conclusions: Cytospecies' distributions have not been stable from 1971 to 2011. Although there are no obvious causes for the temporary appearance and subsequent disappearance of cytospecies in a particular location, a major influence has been vector control and migration patterns, probably explaining observed changes on the Black Volta and lower Volta rivers. Deforestation was previously implicated in an increase of savannah cytospecies in southern Ghana (1975-1997). Our data had little power to support (or refute) suggestions of a continuing increase, except in the Asukawkaw river basin. [ABSTRACT FROM AUTHOR]
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- 2013
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5. Onchocerciasis transmission in Ghana: the human blood index of sibling species of the Simulium damnosum complex
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Lamberton, Poppy H. L., Cheke, Robert A., Walker, Martin, Winskill, Peter, Crainey, J. Lee, Boakye, Daniel A., Osei-Atweneboana, Mike Y., Tirados, Iñaki, Wilson, Michael D., Tetteh-Kumah, Anthony, Otoo, Sampson, Post, Rory J., Basañez, María-Gloria, Wellcome Trust, and The Royal Society
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Adult ,Male ,Human blood index ,Adolescent ,Mycology & Parasitology ,wa_395 ,Host-seeking vectors ,Public Health And Health Services ,Onchocerciasis ,wc_885 ,Ghana ,Ovipositing vectors ,Young Adult ,Vector abundance ,parasitic diseases ,Simulium damnosum (sensu lato) ,Animals ,Humans ,Simuliidae ,Host choice ,Child ,SB ,QR355 ,Research ,Infant ,Feeding Behavior ,Middle Aged ,Insect Vectors ,wa_100 ,wc_695 ,Onchocerca volvulus ,Blood ,Infectious Diseases ,Medical Microbiology ,Child, Preschool ,Female ,Parasitology - Abstract
Background Vector-biting behaviour is important for vector-borne disease (VBD) epidemiology. The proportion of blood meals taken on humans (the human blood index, HBI), is a component of the biting rate per vector on humans in VBD transmission models. Humans are the definitive host of Onchocerca volvulus, but the simuliid vectors feed on a range of animals and HBI is a key indicator of the potential for human onchocerciasis transmission. Ghana has a diversity of Simulium damnosum complex members, which are likely to vary in their HBIs, an important consideration for parameterization of onchocerciasis control and elimination models. Methods Host-seeking and ovipositing S. damnosum (sensu lato) (s.l.) were collected from seven villages in four Ghanaian regions. Taxa were morphologically and molecularly identified. Blood meals from individually stored blackfly abdomens were used for DNA profiling, to identify previous host choice. Household, domestic animal, wild mammal and bird surveys were performed to estimate the density and diversity of potential blood hosts of blackflies. Results A total of 11,107 abdomens of simuliid females (which would have obtained blood meal(s) previously) were tested, with blood meals successfully amplified in 3,772 (34 %). A single-host species was identified in 2,857 (75.7 %) of the blood meals, of which 2,162 (75.7 %) were human. Simulium soubrense Beffa form, S. squamosum C and S. sanctipauli Pra form were the most anthropophagic (HBI = 0.92, 0.86 and 0.70, respectively); S. squamosum E, S. yahense and S. damnosum (sensu stricto) (s.s.)/S. sirbanum were the most zoophagic (HBI = 0.44, 0.53 and 0.63, respectively). The degree of anthropophagy decreased (but not statistically significantly) with increasing ratio of non-human/human blood hosts. Vector to human ratios ranged from 139 to 1,198 blackflies/person. Conclusions DNA profiling can successfully identify blood meals from host-seeking and ovipositing blackflies. Host choice varies according to sibling species, season and capture site/method. There was no evidence that HBI is vector and/or host density dependent. Transmission breakpoints will vary among locations due to differing cytospecies compositions and vector abundances. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1703-2) contains supplementary material, which is available to authorized users.
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