Browsing by Author "Frempong, K.K."
Now showing 1 - 7 of 7
Results Per Page
Sort Options
Item Biting Behavior and Molecular Identification of Aedes aegypti (Diptera: Culicidae) Subspecies in Some Selected Recent Yellow Fever Outbreak Communities in Northern Ghana(Oxford University Press, 2020) Captain-Esoah, M.; Frempong, K.K.; Boakye, D.A.; et al.Aedes aegypti (L.) (Diptera: Culicidae) is a diurnal feeder that lives in close association with human populations. It is the principal vector of yellow fever, dengue fever and the Zika Virus. Issues of arboviral diseases have been on the ascendency in most countries including Ghana where Aedes mosquito is the main vector of yellow fever. A comparative study of the biting behavior of Ae. aegypti and the identification of subspecies were undertaken using molecular technique. Standard human landing technique was used to collect both indoor and outdoor biting mosquitoes at three zones located in the Upper East (Bolgatanga), Upper West (Nadowli), and Northern (Damongo) Regions of Ghana during the dry and rainy seasons between 0600 and 1800 Greenwich Mean Time (GMT). All collected mosquitoes were identified morphologically using taxonomic keys. random amplified polymorphic DNA polymerase chain reaction was used to categorize Ae. aegypti into subspecies. Adult female Aedes mosquitoes identified formed 62% (n = 1,206) of all female mosquitoes collected. Aedes aegypti 98% and Aedes vittatus 2% were the only Aedes species identified. Bolgatanga recorded the largest number of Ae. aegypti 42%, whereas Nadowli 22% recorded the least. Aedes vittatus was observed in Nadowli. Aedes aegypti exhibited a bimodal biting behavior peaking at 0600–0800 GMT and 1500–1600 h GMT. Molecular findings revealed 69% Ae. aegypti aegypti and 31% Ae. aegypti formosus as the two subspecies (n = 110). This information is important for implementing effective vector control programs in the three regions of the northern Ghana.Item Breaking the barrier of cultural differences to advance the course of global medical research through the ISP organized by TMDU(Seibutsu-kogaku Kaishi, 2012-01) Frempong, K.K.Item Characterization of Onchocerca Volvulus Response to Ivermectin Treatment and Identification of Single Nucleotide Polymorphisms Associated With These Responses in Some Onchocerciasis Endemic Regions in Ghana(University of Ghana, 2016-12) Frempong, K.K.In Ghana, onchocerciasis control with mass ivermectin treatment began in 1987. Despite over two decades of interventions, the disease remains persistent with reports of sub-optimal/poor parasite responses to the drug. Some treated patients are observed with higher microfilarial repopulation rates in skin than expected, an indication of sub-optimal response. Although ivermectin is still effective in reducing microfilaridermias, it is uncertain if its embryostatic effect has been compromised. This thesis was to assess the impact of the first 3 years of biannual treatment strategy in Ghana and quantify responses to standard dose of ivermectin in hosts’ skin, assess the drug’s effect on the reproductive capacities of adult female worms and explore any genetic changes in beta-tubulin (β-tub) and P-glycoprotein (P-gp) genes that are believed to be associated with poor response phenotype. The study was carried out in 10 sentinel communities which had received between 15 and 24 years of annual treatment. A community-wide skin snipping was performed on 956 consenting adults aged ≥20 years to assess the community prevalence and intensity of microfilariae. A cohort of 217 participants who were microfilaria positive and/or had palpable nodules at baseline were followed up over the first two rounds of biannual treatment to estimate the rates of microfilarial repopulation. Nodulectomies were performed on consenting participants three months after the third round of treatment. Adult worms (male and female) were isolated from nodules using the collagenase technique. Embryogram analyses were performed and adult female worms classified into three response groups (good, intermediate and poor). DNA was extracted from 60 worms which accurately fitted the response classifications. Polymerase Chain Reaction (PCR) amplifications were performed using specific primers for one region within β-tub and 6 regions within P-gp genes. The amplified products were sequenced and analysed for single nucleotide polymorphisms (SNPs) associated with these responses. The biannual treatment substantially reduced infection intensities in most communities, although infections were detected in all communities even after 4 or 5 rounds of biannual treatments. Asubende, Kyingakrom and New-Longoro communities were identified (all having been previously recognized as responding sub-optimally to ivermectin) with statistically significantly high microfilarial repopulation rates. A total of 225 nodules were excised from 106 participants with an average of about 2 female worms and 1 male worm per nodule. A significantly higher number of female worms (72%) were observed without normal/viable microfilariae (P < 0.0001). There were no clear associations between the years of annual ivermectin treatment prior to biannual and microfilarial repopulation rates or reproductive status of female worms. A multiple sequence alignment showed 10 SNPs that were polymorphic and analysed for any associations. Three of these SNPs were statistically significantly associated with a poor response phenotype i.e. two at positions 1308C/T (P = 0.016) and 1545A/G (P = 0.008) within β-tub and one at position 5546A/G (P = 0.023) within P-gp. Within the β-tub, there was selection at position 1308C/T and some genotypes were present in good responders but absent in poor responders, vice versa. The heterozygosity was found to be reduced within worms sampled from Kintampo/Pru districts compared to those from Kpandai district. Although the biannual treatment in Ghana has made an impact, transmission still exists within some communities, and this is suggested to be driven by a few sub-optimally responding female worms in each community. These sub-optimal responses are also associated with some level of genetic changes. Regular monitoring of parasite responses to ivermectin treatment is necessary to avoid a completely resistant population emerging. Based on these findings, it is uncertain if increasing the frequency of ivermectin treatment (in Ghana) will be sufficient to meet the World Health Organization’s goals of onchocerciasis elimination by 2025.Item New anti-trypanosomal active tetracyclic iridoid isolated from Morinda lucida Benth.(Bioorganic & Medicinal Chemistry Letters, 2015-08) Suzuki, M.; Tung, N.H.; Kwofie, K.D.; Adegle, R.; Amoa-Bosompem, M.; Sakyiamah, M.; Ayertey, F.; Owusu, K.B.-A.; Tuffour, I.; Atchoglo, P.; Frempong, K.K.; Anyan, W.K.; Uto, T.; Morinaga, O.; Yamashita, T.; Aboagye, F.; Appiah, A.A.; Appiah-Opong, R.; Nyarko, A.K.; Yamaoka, S.; Yamaguchi, Y.; Edoh, D.; Koram, K.; Ohta, N.; Boakye, D.A.; Ayi, I.; Shoyama, Y.Human African trypanosomiasis (HAT), commonly known as sleeping sickness has remained a serious health problem in many African countries with thousands of new infected cases annually. Chemotherapy, which is the main form of control against HAT has been characterized lately by the viewpoints of toxicity and drug resistance issues. Recently, there have been a lot of emphases on the use of medicinal plants world-wide. Morinda lucida Benth. is one of the most popular medicinal plants widely distributed in Africa and several groups have reported on its anti-protozoa activities. In this study, we have isolated one novel tetracyclic iridoid, named as molucidin, from the CHCl3 fraction of the M. lucida leaves by bioassay-guided fractionation and purification. Molucidin was structurally elucidated by 1H and 13C NMR including HMQC, HMBC, H–H COSY and NOESY resulting in tetracyclic iridoid skeleton, and its absolute configuration was determined. We have further demonstrated that molucidin presented a strong anti-trypanosomal activity, indicating an IC50 value of 1.27 μM. The cytotoxicity study using human normal and cancer cell lines indicated that molucidin exhibited selectivity index (SI) against two normal fibroblasts greater than 4.73. Furthermore, structure–activity relationship (SAR) study was undertaken with molucidin and oregonin, which is identical to anti-trypanosomal active components of Alnus japonica. Overlapping analysis of the lowest energy conformation of molucidin with oregonin suggested a certain similarities of aromatic rings of both oregonin and molucidin. These results contribute to the future drug design studies for HAT.Item Potential factors influencing lymphatic filariasis transmission in “hotspot” and “control” areas in Ghana: the importance of vectors(BMC, 2019) Frempong, K.K.; Pi-Bansa, S.; et al.Background: Mass drug administration (MDA) programmes for the control of lymphatic filariasis in Ghana, have been ongoing in some endemic districts for 16 years. The current study aimed to assess factors that govern the success of MDA programmes for breaking transmission of lymphatic filariasis in Ghana. Methods: The study was undertaken in two “hotspot” districts (Ahanta West and Kassena Nankana West) and two control districts (Mpohor and Bongo) in Ghana. Mosquitoes were collected and identified using morphological and molecular tools. A proportion of the cibarial armatures of each species was examined. Dissections were performed on Anopheles gambiae for filarial worm detection. A questionnaire was administered to obtain information on MDA compliance and vector control activities. Data were compared between districts to determine factors that might explain persistent transmission of lymphatic filariasis. Results: High numbers of mosquitoes were sampled in Ahanta West district compared to Mpohor district (F = 16. 09, P = 0.002). There was no significant difference between the numbers of mosquitoes collected in Kassena Nankana West and Bongo districts (F = 2.16, P = 0.185). Mansonia species were predominant in Ahanta West district. An. coluzzii mosquitoes were prevalent in all districts. An. melas with infected and infective filarial worms was found only in Ahanta West district. No differences were found in cibarial teeth numbers and shape for mosquito species in the surveyed districts. Reported MDA coverage was high in all districts. The average use of bednet and indoor residual spraying was 82.4 and 66.2%, respectively. There was high compliance in the five preceding MDA rounds in Ahanta West and Kassena Nankana West districts, both considered hotspots of lymphatic filariasis transmission. Conclusions: The study on persistent transmission of lymphatic filariasis in the two areas in Ghana present information that shows the importance of local understanding of factors affecting control and elimination of lymphatic filariasis. Unlike Kassena Nankana West district where transmission dynamics could be explained by initial infection prevalence and low vector densities, ongoing lymphatic filariasis transmission in Ahanta West district might be explained by high biting rates of An. gambiae and initial infection prevalence, coupled with high densities of An. melas and Mansonia vector species that have low or no teeth and exhibiting limitationItem Potential factors influencing lymphatic filariasis transmission in “hotspot” and “control” areas in Ghana: the importance of vectors(Infectious Diseases of Poverty, 2019-02) Pi-Bansa, S.; Osei, J.H.N.; Frempong, K.K.; Elhassan, E.; Akuoko, O.K.; Agyemang, D.; Ahorlu, C.; Appawu, M.A.; Koudou, B.G.; Wilson, M.D.; De Souza, D.K.; Dadzie, S.K.et.alBackground Mass drug administration (MDA) programmes for the control of lymphatic filariasis in Ghana, have been ongoing in some endemic districts for 16 years. The current study aimed to assess factors that govern the success of MDA programmes for breaking transmission of lymphatic filariasis in Ghana. Methods The study was undertaken in two “hotspot” districts (Ahanta West and Kassena Nankana West) and two control districts (Mpohor and Bongo) in Ghana. Mosquitoes were collected and identified using morphological and molecular tools. A proportion of the cibarial armatures of each species was examined. Dissections were performed on Anopheles gambiae for filarial worm detection. A questionnaire was administered to obtain information on MDA compliance and vector control activities. Data were compared between districts to determine factors that might explain persistent transmission of lymphatic filariasis. Results High numbers of mosquitoes were sampled in Ahanta West district compared to Mpohor district (F = 16.09, P = 0.002). There was no significant difference between the numbers of mosquitoes collected in Kassena Nankana West and Bongo districts (F = 2.16, P = 0.185). Mansonia species were predominant in Ahanta West district. An. coluzzii mosquitoes were prevalent in all districts. An. melas with infected and infective filarial worms was found only in Ahanta West district. No differences were found in cibarial teeth numbers and shape for mosquito species in the surveyed districts. Reported MDA coverage was high in all districts. The average use of bednet and indoor residual spraying was 82.4 and 66.2%, respectively. There was high compliance in the five preceding MDA rounds in Ahanta West and Kassena Nankana West districts, both considered hotspots of lymphatic filariasis transmission. Conclusions The study on persistent transmission of lymphatic filariasis in the two areas in Ghana present information that shows the importance of local understanding of factors affecting control and elimination of lymphatic filariasis. Unlike Kassena Nankana West district where transmission dynamics could be explained by initial infection prevalence and low vector densities, ongoing lymphatic filariasis transmission in Ahanta West district might be explained by high biting rates of An. gambiae and initial infection prevalence, coupled with high densities of An. melas and Mansonia vector species that have low or no teeth and exhibiting limitation. Electronic supplementary material The online version of this article (10.1186/s40249-019-0520-1) contains supplementary material, which is available to authorized users.Item Progress towards lymphatic filariasis elimination in Ghana from 2000-2016: Analysis of microfilaria prevalence data from 430 communities(PLoS Neglected Tropical Diseases, 2019-06-05) Frempong, K.K.; Biritwum, N.K.; Verver, S.; Odoom, S.; Alomatu, B.; Asiedu, O.; Kontoroupis, P.; Yeboah, A.; Hervie, E.T.; Marfo, B.; Boakye, D.A.; De Vlas, S.J.; Gyapong, J.O.; Stolk, W.A.BACKGROUND: Ghana started its national programme to eliminate lymphatic filariasis (LF) in 2000, with mass drug administration (MDA) with ivermectin and albendazole as main strategy. We review the progress towards elimination that was made by 2016 for all endemic districts of Ghana and analyze microfilaria (mf) prevalence from sentinel and spot-check sites in endemic districts. METHODS: We reviewed district level data on the history of MDA and outcomes of transmission assessment surveys (TAS). We further collated and analyzed mf prevalence data from sentinel and spot-check sites. RESULTS: MDA was initiated in 2001-2006 in all 98 endemic districts; by the end of 2016, 81 had stopped MDA after passing TAS and after an average of 11 rounds of treatment (range 8-14 rounds). The median reported coverage for the communities was 77-80%. Mf prevalence survey data were available for 430 communities from 78/98 endemic districts. Baseline mf prevalence data were available for 53 communities, with an average mf prevalence of 8.7% (0-45.7%). Repeated measurements were available for 78 communities, showing a steep decrease in mean mf prevalence in the first few years of MDA, followed by a gradual further decline. In the 2013 and 2014 surveys, 7 and 10 communities respectively were identified with mf prevalence still above 1% (maximum 5.6%). Fifteen of the communities above threshold are all within districts where MDA was still ongoing by 2016. CONCLUSIONS: The MDA programme of the Ghana Health Services has reduced mf prevalence in sentinel sites below the 1% threshold in 81/98 endemic districts in Ghana, yet 15 communities within 13 districts (MDA ongoing by 2016) had higher prevalence than this threshold during the surveys in 2013 and 2014. These districts may need to intensify interventions to achieve the WHO 2020 target.