School of Biological Sciences
Permanent URI for this communityhttp://197.255.125.131:4000/handle/123456789/4911
Browse
110 results
Search Results
Item Physicochemical, Functional Properties And Mycotoxin Occurrence Of Ghanaian Tigernuts (Cyperus Esculentus L.)(University of Ghana, 2022-06) Battuta-DawlahIn Ghana, tigernut (Cyperus esculentus L.) is grossly underutilized in food applications and is mostly consumed raw as a snack. However, the soil and climate conditions of the country are conducive for cultivation of the crop on a large scale for applications in food for local consumption, industrialisation and for the export market. Food applications of tigernut and its derivatives and their possible inclusion as ingredient in the Ghanaian diet would require knowledge on its handling quality and functional properties. The aim of this study was to characterise Ghanaian tigernut as an ingredient for possible food applications. The study design consisted of two parts: (a) a cross-sectional survey of different categories of stakeholders using pre-tested semi-structured questionnaires (b) followed by laboratory designed experiments to study the quality, physicochemical and functional properties of tigernut as a function of tigernut variety and process conditions. For the surveys, a total of 1277 stakeholders in the value chain, comprising of 711 consumers and 487 traders (wholesalers/retailers) in Greater Accra region and 79 tigernut farmers in the Western and Eastern regions of Ghana, were interviewed using semi-structured researcher-administered questionnaires. The questionnaires sought to gain information on respondents’ level of knowledge on mycotoxins, as well as ascertain if measures were in place to mitigate the risk of fungal colonisation of the crop along the supply chain. Additionally, tigernuts collected at various points along the supply chain (farm, wholesale and retail) were analysed for their mycotoxin (aflatoxins and ochratoxin A) levels using reverse phase High-Performance Liquid Chromatography (HPLC), to determine the hot spots of mycotoxin contamination along the value chain. The second part of the study investigated the physical characteristics of tigernut tubers as well as the functional properties of tigernut flour with the aim of determining its suitability in food applications. Additionally, the shelf life of the tigernut flour was determined by accelerated shelf life testing using the Arrhenius model. Fresh tigernut milk is usually University of Ghana http://ugspace.ug.edu.gh iii characterised by the sedimentation of starch which influences its flow behaviour as well as the physical stability. Furthermore, heat treatment of the milk leads to gelatinisation of the starches, which also affects the same properties. Consequently, the effects of heat (by roasting tigernuts) and adding α- amylase to the tigernut milk on the physicochemical and functional properties of tiger nut milk were studied. Tigernut oil was extracted and the phenolic and functional properties were determined as well as the effect of heat on these properties. The macro nutritional composition of tigernut tuber, flour, oil and milk were also investigated. The results of the surveys showed that tigernut farmers and consumers had appreciable knowledge in and displayed better attitude towards the prevention of mycotoxin contamination than the tigernut traders (wholesalers/retailers). The educational level of all stakeholders influenced their attitude and knowledge towards the prevention of mycotoxin contamination. Almost all consumers were willing to try new tigernut products such as the flour, oil and milk and would like to see more of these products on the Ghanaian market. The number of samples and the levels of mycotoxins (Ochratoxin A and aflatoxins) increased as the value chain progressed, with retail samples containing all the mycotoxins analysed. Total mycotoxins ranged from 0-27 µg/kg at the farm stage to 0-52 µg/kg at the wholesale stage and finally to 7.9 to 1115.48 µg/kg at the retail stage. These highlight post-harvest stage of the value chain as the focal point for mycotoxin prevention programs, although mycotoxin prevention can be agreed as a cumulative process. Both black and yellowish-brown tigernut flours contained relatively high and comparable amounts of sucrose, glucose and fructose. The relatively high resistant starch content of the tigernut flour makes the flour ideal for diabetics and weight watchers. The yellowish-brown variety had higher total starch content, higher water-retaining ability and viscosity at heating and holding cycles as compared to the black variety. Titratable acidity was found to be the crucial determinant of spoilage in tigernut flour and higher temperature was observed to increase the oxidation of the tigernut flour. This may imply that tigernut flour should be stored below room temperature. Heat and the addition of α- amylase increased the total solids, brix and titratable acidity but caused a decrease in the pH of the tigernut milk. Addition of 0.2% of α- amylase to roasted tigernut milk improved its emulsion stability. Heat and addition of α- amylase caused the tigernut milk to become darker in colour. The flow behaviour of the tigernut milk exhibited shear thinning (pseudoplastic) fluid properties. This implies that commercial production of milk from tigernut must control parameters such as speed of machines during processing as well as concentrations of food additives such as α-amylase. Chemical qualities such as iodine value, peroxide value, ester value, saponification value, free fatty acids and acid value of oil extracted from tigernut tubers, all increased at higher temperatures whilst antioxidant activity and phenolic content decreased. The functional properties of tigernut oil suggested that the oil is good for frying at lower temperatures and for shorter periods. The carbohydrate component of the tigernut tuber was mainly made up of starch and dietary fibre (resistant starches) which reduced in the milk and oil. Crude fat was the second most abundant component in the tigernut tuber. Quercetin and gallic acid were found in appreciable amounts in the tigernut oil. Although, the protein content in the tigernut milk was lower compared to the tuber, it was probably enough to impart desirable functionality to help stabilize the tigernut milk. Tigernut tuber and its derivatives can offer various options in food products. The safety of the tuber and its products can however be improved when stakeholders of the supply chain are educated and supported to implement strategies that prevent mycotoxin contamination.Item Modelling The Relationship Between The West African Mangrove Oyster (Crassostrea Tulipa, L.1819) And The Aquatic And Climatic Environment For Use As A Bio-Indicator In The Densu Estuary(University of Ghana, 2021-09) Atindana, S. A.Crassostrea tulipa (Lamarck, 1819) in the Densu estuary was investigated from March 2019 to August 2020 for aspects of its ecology; it’s potential as a bio-indicator of environmental variability; and long-term effects of climate variability on shellfish production in Ghana’s artisanal fisheries and its implication on sustainable management of oyster fisheries. Oyster samples were collected monthly and physicochemical parameters namely Temperature (OC), Dissolved Oxygen (mg/L), pH, Total Dissolved Substances (mg/L), Conductivity (µS/cm) and Salinity (0 /00) measured in situ in triplicates. Silicates, Total Alkalinity, Chlorophyll a, microbes (Total Viable Counts, faecal coliform and Escherichia coli) and heavy metals (Lead, Cadmium and Mercury) were measured ex situ following standards of APHA (2015). Relative abundance was measured as Catch Per Unit Effort (CPUE) and growth pattern determined using the TropFishR package in R programming software. The numerical and frequency of occurrence methods were used to determine its food habits. Species-environmental driver relationship was analyzed following Canonical Correspondence Analysis (CCA) approach using the Vegan package (version 2.5-4.) in R studio software (version1.3.1056). CPUE from experimental fishing was significantly (p < 0.05) higher (6-200; 233.33 ± 6.00 kg/hr/fisher/day) than commercial fishing (3-100;78.12 ± 7.11 kg/hr/fisher/day). CPUE was significantly higher (p = 0.0161) at low tide (115-500;50.10 ± 5.3 kg/hr/fisher/day) than high tide (6-200; 62.58 ± 3.12 kg/hr/fisher/day). CPUE was higher (p = 0.023) in the dry season (150.87 ± 1.12 kg/hr/fisher/day) than the rainy season (57.45 ± 0.55 kg/hr/fisher/day). Crassostrea tulipa has a fast growth rate (K= 0.81; L∞ = 13.24 cm). Higher condition index (60 %) was recorded in the rainy season than the dry season (39 %). University of Ghana http://ugspace.ug.edu.gh iv The diet of the oyster was predominated by golden algae (IRI=595), red algae (IRI=209), green algae (IRI=131.37) and diatoms (IRI =172). Densu estuary is a dynamic shallow system with high concentration of total alkalinity and aragonite. Water depth, silicates, e coli and revelle factor were significantly higher (p < 0.05) at high tide than low tide. Also, mean water depth, cadmium, total alkalinity, pH, carbon dioxide, lead, total carbon dioxide, carbon dioxide fugacity and chlorophyll a were significantly higher (p< 0.05) bio accumulated Pb and Cd than big- sized (4.5-5.4g) tissues. Lead, mercury, TVC, faecal coliform and Escherichia coli also bio accumulated in C. tulipa tissues more (BAF > 1) than in the water medium which suggests that it has the ability to provide a measurable response to changes in the estuarine environment. Therefore, C. tulipa in the Densu estuary has the ability to accumulate pollutants from the environment and its morphometric features could give clues on the state of environmental variables. C. tulipa is a good bioindicator for assessing; lead, mercury, Total viable counts, E coli and faecal coliform in the Densu estuary. Densu estuary is high in aragonite and total alkalinity. The predictor variables for; Condition factor is aragonite, shellfish catch is temperature and Shell height & Width are faecal coliform, total carbon dioxide and carbon dioxide fugacity. There is the occurrence of contamination and therefore the need for regular monitoring, enactment of control measures and depuration prior to consumption. Also, the use of refuse dam and sewage outlet should be prohibited. It is recommended that laboratory and field-controlled experiments be conducted on oyster responses to extremes of temperature, aragonite and total alkalinity. There is an urgent need for the collation of data on estuarine/lagoonal shellfisheries in Ghana by Fisheries Commission and other stakeholders on catch trends, gears, effort and income of artisanal oyster collectors.Item Mapping The Kinetics And Diversity Of Adaptive Immune Responses In Children Over The Course Of An Acute Plasmodium Falciparum Infection(University Of Ghana, 2021-07) Nyakoe, N.K.Naturally acquired immunity to malaria is Plasmodium species strain- and variant- specific. It is non-sterile and short-lived therefore requiring repeated exposure. These protective immune responses are directed against pre-erythrocytic parasites, blood-stage merozoites, or Plasmodium antigens on the surface of infected red blood cells and can be humoral or cellular. The importance of the various immune response components during malaria episodes in exposed populations remains unknown, as conclusive interpretation of data from previous studies has been limited by sampling design, disease definition, patient selection and approaches in natural infections. Long-term malaria protection in humans is likely to be determined by the cumulative effect of multiple low-level immune responses to various antigens, with each person having a unique "protective signature" based on their genetic background. Differences in transmission intensity observed in malaria-endemic areas significantly influence the acquisition of natural immunity to malaria. Antibody and cytokine responses, which contribute to malaria protective immunity, are exposure-dependent; hence, are significantly influenced by transmission intensity. Cytokine levels change rapidly upon exposure to malaria and often dictate the extent of clinical disease, whereas antibodies increase gradually and are long-lasting, and act to control and eliminate parasites. A variety of molecular mechanisms are involved in regulating these immune responses; however, it is still unclear what combination of immune features is essential for protection. Characterization of these host immune responses is important in understanding the bidirectional host-parasite interactions which will aid in effective vaccine development and eventual malaria control and elimination. This study employed a systems immunological approach to profile changes in the cellular, humoral, and molecular components of the immune system during acute P. falciparum infection and after treatment to identify immune signatures associated with varying malaria transmission intensity. Methods: Samples were collected from children of ages 5-14 years in two regions in Ghana with distinct malaria transmission intensities: Accra (low transmission) and Kintampo (high transmission). Whole blood samples were collected and a portion separated to obtain plasma from the participants when they present at the hospital with confirmed P. falciparum infection (Day 0), and convalescent phases (Day 7 and Day 21). Levels of 25 plasma cytokines were determined using a multiplex Luminex human magnetic 25-plex bead array kit. A custom-made protein microarray was used to detect IgG responses to 190 antigenic targets for blood-stage, pre-erythrocytic, and gametocyte stage parasite proteins. Antibodies and cytokine levels from the 2 sites were compared during infection and convalescent phases. Additionally, whole-blood transcriptomes were profiled by RNA-sequencing and differential gene expression compared during infection and convalescent in the study participants. Correlation and machine-learning classifier approaches were used to model immune responses to identify predictive responses correlating with distinct transmission intensities. Gene ontology modules associated with changes in immune responses in the two transmission areas were identified using gene set enrichment analysis. Results: Acute P. falciparum infection was associated with pro-inflammatory cytokines IL-6, IFN-γ, IFN-α, MIG, MCP-1, and IP-10, as well as an immunomodulatory profile mediated by IL-10, IL-2R and IL-1RA. In children from low transmission areas, they were significantly higher than in children in the high transmission areas, whereas, IFN-α, IL-6, IL-1RA, and MCP-1 were significantly associated with parasitemia. In addition, analysis of the correlation network revealed a distinctive signature between individuals from the low and high transmission areas. Of interest, is a subset of children from the high transmission area with detectable parasitemia at day 21 (D21) after treatment, with a unique cytokine signature dominated by IL-10 and IL-1RA. This was associated with asymptomatic parasitemia. Of the 190 Plasmodium antigens tested, 118 had antibody reactivity in more than 80% of the children in our study cohorts. Though overall breadth and magnitude of antibody responses was similar, the composition of these responses was different between individuals from high and low transmission areas. Hierarchical clustering revealed IgG response clusters to antigens associated with different malaria endemicity, with 48/118 antigens including EBA140, ETRAMP5, GLURP, MSP1 and MSP6 associated to low transmission area and 30/118 antigens associated to high transmission area, including Rh5.1, EBA181, VAR2CSA, ACS5, HSP40, MSP2, MSP3, MSP4, and MSP7. Machine-learning and feature selection approaches further predicted 17 antibody signatures (MSP4, MSP2 3D7, MSP1-19 2A, Etramp 5 Ag1 His var 3, MSP1-19 2B, Etramp 5 Ag1 His var 2, MSP2 [15-46b], MSP2 [5-36A], ACS5 Ag 3, PfMSP1_19, MSP3 FVO, Var2CSA, SE36/SERA 5 (T), HSP40 Ag 3, GLURP R2, Rh4.2_2030, and MSP2 CH150/9) that distinguish individuals from these two regions. Multivariable linear regression models predicted age and transmission intensity as factors that highly affect antibody reactivity to most antigens in our panel. Gene expression levels differ with transmission intensity More genes were differentially expressed during infection (D0) compared to convalesces (D7 and D21). Comparison of the DEGs between the two sites show that more genes were highly expressed in low transmission area compared to the high transmission area at D0. In the high transmission area, the DEGs enriched in gene ontology (GO) modules related to B cell and surface signature, T cell development and activation, platelet activation-actin binding, enriched cell cycle, and regulation of transcription and transcription factor modules, were up-regulated. In the low transmission area, there was DEGs in modules associated with cell cycle and transcription, immune activation- generic cluster, E2F1 targets, plasma cell surface signature, immunoglobulins, enriched monocytes, enriched NK cells, platelet activation, enriched neutrophils, enriched activated dendritic cells, NK cell surface signature, chemokine and inflammatory molecules in myeloid cells, Golgi membrane and TBA modules, were up-regulated. Cellular deconvolution revealed an increased proportion of neutrophils cell type in both high and low transmission areas, with decreased CD4 naïve, CD8, B-cells and T-follicular cells, during infection compared to convalescence in both high and low transmission. Our data identified transcription patterns that are distinguish by malaria transmission intensity, where most genes highly expressed in the high transmission area are those involved in adaptive immune response. While genes highly expressed in the low transmission area are those involve in the innate immune response. These data provide insight into molecular and cellular immune response kinetics in natural infection. Conclusion: The findings show that cytokine responses during active malaria infection varies significantly between individuals with differing levels of prior exposure, with individuals from low transmission settings having higher levels of pro-inflammatory cytokines. However, these differences are transient and do not persist during recovery. Whereas antibodies levels remained relatively stable across the timepoints for most antigens in our panel. We show that models trained to capture distinct antibody response patterns predicted 17 antibody responses that are key in distinguishing between individuals from different intensities. Given the important role that exposure plays in the acquisition of immunity these could be useful antigens as possible targets of protective immunity and provides clues for potential vaccine candidates that can be prioritized in evaluation. Transcriptomic analysis of whole blood over the course of infection revealed molecular signatures that can provide insights into the protective immune responses against P. falciparum infection. We identified genes whose expression patterns can help differentiate changes during acute P. falciparum infection and convalesces in varying transmission intensity. Taken together, this study predicts humoral and cellular signatures associated with the acquisition of naturally acquired immunity that can fairly distinguish individuals from two distinct transmission areas based on their immune profileItem Potential Transmission Of Zoonoses Between The Human-Domestic-Wildlife Interface And Its Implication For Sustainable Health.(University Of Ghana, 2021-09) Amoah, L.A.OZoonoses have been of great public health concern and a global phenomenon that continues to challenge both veterinary and human health systems. The risk of zoonoses is predicted to be higher in domestic settings where animals are constantly in close contact with humans and exposure to zoonotic pathogens is very high. In Ghana, some studies to identify zoonotic diseases transmitted by domestic animals or animals in the wild usually consider either the human-domestic interface or human-wildlife interface. Considering that in recent times diseases continue to emerge from unexpected reservoir hosts and through novel pathways, this study investigated zoonotic diseases that are potentially transmissible by domestic and wild animals to humans across the human-domestic-wildlife interface. It also assessed the awareness and knowledge of owners of companion animals on zoonoses in two human-dominated landscapes. The cross-sectional study involved fieldwork and laboratory processing of biological samples from dogs, cats, and rodents using molecular techniques. Specifically, Polymerase Chain Reaction (PCR) and gel electrophoresis were used to investigate the presence or absence of zoonotic pathogens in biological samples. In addition, questionnaires were administered to owners of companion animals in households and veterinary institutions in designated study areas. Secondary data on zoonotic diseases presented at selected health facilities were also accessed and evaluated to complement the field data. Overall, 404 animals comprising 185(45.8%) dogs, 15(3.7%) cats and 204 (50.5%) rodents were sampled from households, veterinary institutions and selected study sites. In all, seven (7) species of rodents were trapped with Arvicanthis niloticus and Praomys tullbergi identified as the dominant species in the urban and peri-urban areas, respectively. The prevalence of Babesia spp. was the highest (80.7%), followed by Staphylococcus spp. (72.5%) and the least was Ancylostoma spp. (18.1%). For zoonotic helminths (Toxocara canis, Strongyloides stercoralis and Ancylostoma spp.), a prevalence of 30.12% was recorded. The study found significant differences in the prevalence of T. canis (p<0.001), S. stercoralis (p=0.033), and Salmonella spp. (p<0.001), Staphylococcus spp. (p=0.017) and Babesia spp. (p=0.029) between the two human-dominated landscapes. Similarly, there were significant differences in the prevalence of T. canis (p=0.034), S. stercoralis (p<0.001) and Babesia spp. (p<0.001) between the households and veterinary institutions as well as among sampled animals (p<0.05). On the whole, 13.9% of sampled animals had a single or mono-zoonotic infection, while 80.9% were co-infected with multiple zoonotic pathogens. Additionally, medical records from Shai-Osudoku and Pentecost Hospitals revealed that helminth infections were the commonest zoonoses presented by clients, particularly those under 18 years old. Conversely, staphylococcal infections were the highest zoonotic infections reported by clients of the University of Ghana Hospital. Again, 33.8% of 230 respondents who participated in the survey owned companion animals for companionship or as part of the family. Remarkably, 38.9% of the respondents had never dewormed their companion animals. While 62% of respondents had vaccinated their animals, 10.1% did it over a year ago, implying that about 48.1% of these animals were at risk of infectious diseases and could transmit the same to their owners. Furthermore, significant positive associations were found between the educational level of respondents and the frequency of vaccinating pets (rs =0.254, p<0.001) as well as respondents’ knowledge of causes or sources of zoonoses (rs =0.141, p=0.049). On the contrary, there was a significant negative association between the frequency of deworming pets and the main reason for keeping such animals (rs =-0.203, p=0.011) besides the prevention of zoonoses (rs =-0.260, p=0.001). Findings from this study indicate companion animals and rodents are reservoir hosts to zoonotic pathogens of public health importance that can potentially be transmissible to their owners and the community. Also, because these animals are co-infected with multiple zoonotic pathogens, it suggests there could be serious implications for sustainable health, which SDG 3 seeks to achieve. Data from the animal interface and the medical records from the human interface indicate the potential transmission of zoonoses, especially helminthiasis, in the studied communities. In addition, the urban areas were identified to best support the potential transmission of zoonoses contrary to the peri-urban areas. Thus, active surveillance of zoonoses in animals in close contact with humans in our urban and peri-urban communities is urgently required. Again, respondents had some knowledge of zoonotic diseases from companion animals, although most were ignorant of zoonoses from rodents. Findings from the survey indicate that a high proportion of owners of companion animals in the study areas were engaged in activities that predispose them to zoonotic diseases. It is recommended that public education campaigns and awareness creation programmes using a one-health approach should be started in earnest to ensure the effective prevention and control of zoonotic diseases.Item Modelling The Relationship Between The West African Mangrove Oyster (Crassostrea Tulipa, L.1819) And The Aquatic And Climatic Environment For Use As A Bio-Indicator In The Densu Estuary(University of Ghana, 2021-09) Atindana, S.AABSTRACT Crassostrea tulipa (Lamarck, 1819) in the Densu estuary was investigated from March 2019 to August 2020 for aspects of its ecology; it’s potential as a bio-indicator of environmental variability; and long-term effects of climate variability on shellfish production in Ghana’s artisanal fisheries and its implication on sustainable management of oyster fisheries. Oyster samples were collected monthly and physicochemical parameters namely Temperature (OC), Dissolved Oxygen (mg/L), pH, Total Dissolved Substances (mg/L), Conductivity (μS/cm) and Salinity (0/00) measured in situ in triplicates. Silicates, Total Alkalinity, Chlorophyll a, microbes (Total Viable Counts, faecal coliform and Escherichia coli) and heavy metals (Lead, Cadmium and Mercury) were measured ex situ following standards of APHA (2015). Relative abundance was measured as Catch Per Unit Effort (CPUE) and growth pattern determined using the TropFishR package in R programming software. The numerical and frequency of occurrence methods were used to determine its food habits. Species-environmental driver relationship was analyzed following Canonical Correspondence Analysis (CCA) approach using the Vegan package (version 2.5-4.) in R studio software (version1.3.1056). CPUE from experimental fishing was significantly (p < 0.05) higher (6-200; 233.33 ± 6.00 kg/hr/fisher/day) than commercial fishing (3-100;78.12 ± 7.11 kg/hr/fisher/day). CPUE was significantly higher (p = 0.0161) at low tide (115-500;50.10 ± 5.3 kg/hr/fisher/day) than high tide (6-200; 62.58 ± 3.12 kg/hr/fisher/day). CPUE was higher (p = 0.023) in the dry season (150.87 ± 1.12 kg/hr/fisher/day) than the rainy season (57.45 ± 0.55 kg/hr/fisher/day). Crassostrea tulipa has a fast growth rate (K= 0.81; L∞ = 13.24 cm). Higher condition index (60 %) was recorded in the rainy season than the dry season (39 %). The diet of the oyster was predominated by golden algae (IRI=595), red algae (IRI=209), green algae (IRI=131.37) and diatoms (IRI =172). Densu estuary is a dynamic shallow system with high concentration of total alkalinity and aragonite. Water depth, silicates, e coli and revelle factor were significantly higher (p < 0.05) at high tide than low tide. Also, mean water depth, cadmium, total alkalinity, pH, carbon dioxide, lead, total carbon dioxide, carbon dioxide fugacity and chlorophyll a were significantly higher (p<0.05) in the rainy season than the dry season. The simple linear regression models for forecasting shell height, shell width, condition factor and relative abundance are respectively described as follows: Shell Height (n=1800) = -0.006.673 faecal coliform (CFU/ml) - 0.002933 Total carbon dioxide -0.0002556 carbon dioxide fugacity The coefficient of determination, R2, of 0.5226 explained about 52.26 % of the variability in shell height. Shell Width (n = 1800) = -0.02262 faecal coliform (CFU/ml) + 0.00089 Total carbon dioxide -0.0000722 carbon dioxide fugacity Approximately 41.02 % (R2) of the variability in shell width is attributable to faecal coliform, total carbon dioxide and carbon dioxide fugacity. Also, an R2, of 0.5743 shows that 57.43 % of the changes in condition factor was explained by aragonite content and the model describing it is, Condition Factor (n = 1800) = 65.646 Aragonite About 26.05 % (R2) of the oyster abundance is due to temperature. Oyster Catch Per Unit Effort (n = 1080) = - 35.51973 Surface Water Temperature (OC) Also 91 % (R2) of the variations in shellfish catch is due to temperature following the model. Shellfish catch per unit effort = −7788.067 + (265.312 SST) Except for mercury, small- sized oyster (2.5-3.5g) tissues significantly (p < 0.05) bio accumulated Pb and Cd than big- sized (4.5-5.4g) tissues. Lead, mercury, TVC, faecal coliform and Escherichia coli also bio accumulated in C. tulipa tissues more (BAF > 1) than in the water medium which suggests that it has the ability to provide a measurable response to changes in the estuarine environment. Therefore, C. tulipa in the Densu estuary has the ability to accumulate pollutants from the environment and its morphometric features could give clues on the state of environmental variables. C. tulipa is a good bioindicator for assessing; lead, mercury, Total viable counts, E coli and faecal coliform in the Densu estuary. Densu estuary is high in aragonite and total alkalinity. The predictor variables for; Condition factor is aragonite, shellfish catch is temperature and Shell height & Width are faecal coliform, total carbon dioxide and carbon dioxide fugacity. There is the occurrence of contamination and therefore the need for regular monitoring, enactment of control measures and depuration prior to consumption. Also, the use of refuse dam and sewage outlet should be prohibited. It is recommended that laboratory and field-controlled experiments be conducted on oyster responses to extremes of temperature, aragonite and total alkalinity. There is an urgent need for the collation of data on estuarine/lagoonal shellfisheries in Ghana by Fisheries Commission and other stakeholders on catch trends, gears, effort and income of artisanal oyster collectors.Item Assessment Of Rearing Technique For The Black Soldier Fly And Termite Collection Technique For Use By Smallholder Poultry And Fish Farmers In Ghana.(University Of Ghana, 2020-11) Boafo, H.A.Insects offer a cheap source of protein for especially smallholder poultry and fish farmers. Insects contain about 40-70 % protein, 35 % fat, and other micro-nutrients. The black soldier fly (BSF) larvae and termites are promising insects that can replace the animal protein component of livestock feed. The full adoption of their use by farmers is however slow due to insufficient scientific data on the production of BSF larvae and termite collection techniques. In this study, the existing production techniques for BSF larvae and collection of termites were evaluated to recommend the most efficient for adoption by smallholder poultry and fish farmers. Six organic substrates (pito mash, millet porridge mash, pig manure, chicken manure, fruit waste, and waste from roots and tubers) known to be suitable for BSF larvae production were evaluated for their suitability as oviposition attractants and larval development. The substrates were first exposed outdoors to measure the quantity of eggs laid on them by naturally occurring BSF females. The quality of the substrate(s) as larval rearing media was also tested by placing a standard amount of egg mass to measure the individual and total weights of prepupae obtained, total number, and development time. The nutritional profile of the prepupae and the substrates were also determined. Furthermore, the production of BSF larvae under natural oviposition (in garden bins) was assessed by varying the rate of loading substrate (pito mash) and the quantities of the substrate on the overall prepupal harvest. The substrate used significantly influenced the quantity of eggs laid and the development of the resulting prepupae but the substrates most favourable for larval development were not the most favoured by gravid BSF for oviposition. In the oviposition tests, millet porridge mash was the most attractive substrate whereas only a few eggs were recovered from the other substrates. All substrates allowed the successful development of larvae but pig manure was more productive than the others. The crude protein content of the larvae ranged between 35 - 43%, with the shortest development time of 16 days. Applying small quantities of substrates at a constant rate (10 kg per week) in garden bins produced higher prepupal yields than larger quantities (20 kg). Unlike BSF larvae, termites cannot be easily produced but are obtained from chippings of mounds or by trapping using containers with filled organic matter. The commonly used termite collection method was assessed to quantify the amount of termites harvested with commonly used organic matter. Furthermore, indigenous knowledge on the use of termites as poultry feed in Ghana and factors affecting its use were assessed. Containers filled with the four commonly used organic matter (mango seed, maize cobs, dried cow dung, yam peels, and their mixtures) were placed on trails of termites to quantify the daily harvest. Surveys were also conducted in four regions in Ghana to collect information, by the administration of questionnaires, on the use of termites as poultry feed, termite species collected, species not used, and collection methods. Samples of termite species mentioned were collected and identified to the genus level. Twenty-three per cent and 19% of farmers mentioned that termites are always or often used to feed poultry whereas 11% never use termites. A binomial regression analysis showed that termite use was affected by region, sex, education, farm size, and income. Termites collected belonged to eight genera, the main ones being Macrotermes, Trinervitermes, and Odontotermes. Five collection methods are used to obtain termites and involve either breaking mounds or using containers as traps. Collection methods vary with species and region and the abundance of termite genera varies with season. Farmers identified some species as poisonous to poultry. A Kruskal-Wallis test showed that there were significant differences in the quantity of termites collected using different substrates for both Odontotermes species and Macrotermes species. A mixture of corn cobs and yam peels yielded the highest dry weight harvest of 14.8 g/day in Macrotermes species. Likewise, the mixture of mango seed and cow dung gave the highest average yield of 19.40 g/day dry weight of Odontotermes species. Termites and black soldier fly larvae are important in indigenous poultry production because they are a readily available and cheap protein source for local farmers.Item Predictors Of Potentially High Risk For Preeclampsia Among Pregnant Women Attending Antenatal Clinics At Selected Hospitals In Accra(University Of Ghana, 2021-07) Abban, H.A.Introduction: Preeclampsia/Toxemia (PE) is a genuine hypertension condition related with maternal and infant ill health and death during pregnancy. Preeclamptics as well as their babies/children develop health conditions including cardiovascular disease as well as growth conditions well along in life. In Ghana, prevalence of PE has been known to be as low as 2.5% in Ghana Police hospital and as high as 48.8% in Komfo Anokye Teaching Hospital. Most of the studies carried out on PE has been case control and hence do not have enough data on the possible exposures at the early stages of pregnancy which may have led to the developing of PE. Also only a few studies has been carried out on the predictors associated with preeclampsia. Objective: This current prospective cohort study sought to determine the factors at the various stages of pregnancy; ≤ 20 weeks gestation through 28 –32 weeks and during 6 weeks postpartum which may predispose the pregnant women to a potentially high risk for PE. Methodology: This was prospective cohort study involving 403 pregnant women who were recruited at ≤ 20 weeks gestation. Nonetheless, 21 participants dropped out between weeks 28 and 32, and 24 participants also dropped out at 6 weeks postpartum leaving 358 participants in the study. The study took place at the Ghana Police Hospital, Cantonment, and the University of Ghana Hospital, Legon, both in Accra. The entire study lasted for 21 months (May, 2018 – Feb.2020). Structured questionnaires that had been pre-tested were used to obtain information on the participants' backgrounds, lifestyle practices, gynecological factors, dietary factors, stress status, BMI, biochemical data (haemoglobin, proteinuria), clinical data (blood pressure), family history of chronic conditions, morbidities among other factors. The criteria used for potentially high risk for preeclampsia was having at least a systolic blood pressure of ≥130 mmHg or diastolic blood pressure of ≥80 mmHg or oedema or proteiunuria. Background categorical variables were computed as frequencies and percentages, whereas continuous variables were enumerated as median (interquartile range; Q1, Q3) or means ± SD, as appropriate. The predictors of possibly high risk for PE were investigated using binary logistic regression and finally path analysis was run to determine the path way through which the predictors operate. Results: The age on average of expectant mothers is 31 ± 5 years, a greater number 194 (48%) of expectant mothers had attained tertiary education, median gestational age at first time ante natal booking was 14 (12, 17) weeks, Akan ethnicity was dominating 166 (41.0%) and 347 (86.0%) of the women were married. Prevalence of serum vitamin D and calcium deficiencies were 48.3% and 53.2% respectively with 34.0% being at a potentially high risk for PE. Predictors of potentially high risk for PE were the following; estimated pre – pregnancy body mass index (≥ 30 kg/m2) AOR = 3.6 (95% CI = 1.01 – 11.750) p value 0.040 and estimated pre- pregnancy weight (> 71 kg) AOR = 3.4 (95% CI = 1.250 - 12.703) p 0.019. From path analysis, path relationship for anthropometric indices (estimated pre – pregnancy BMI and estimated pre- pregnancy weight) and potentially high risk for preeclampsia shows a favorable and significant direct association (β = 0.519; t-value = 8.545; p-value = 0.001). Conclusion: Predictors of potentially high risk for PE among the participants were estimated pre-pregnancy BMI and estimated pre-pregnancy weight (weight measured at the first antenatal clinic). In contrast to findings of most studies, serum vitamin D and calcium deficiencies had no association with PE.Item Antimicrobial Resistance Of Foodborne Pathogens In Stool Of Diarrhoea Patients In Two Selected Health Facilities And Food From Vendors In Selected Communities In Ghana(University Of Ghana, 2021-12) Dela, H.Foodborne pathogens (FBPs) have been implicated as the cause of so many food poisonings and outbreaks worldwide. Food borne bacteria are the second most common FBP after viruses in causing public health threat due to the gradual emergence of antimicrobial resistance (AMR) in the food chain. Although contaminated food is frequently implicated as the cause of diarrhoeal-related hospitalization, especially during outbreak investigations in Ghana, integrated surveillance has not been conducted to ascertain this fact. This study engaged the various transdisciplinary sectors in human and environmental health to show the holistic approach in understanding the occurrence of AMR of foodborne bacteria in Ghana. Stool of patients attending Maamobi General hospital and Kaneshie polyclinic were collected, and questionnaire administered to patients to understand the risk factors involved in diarrhoea transmission. Ready-to-eat (RTE) food and water were collected from food vendors, palm swabs of food vendors as well as responses on possible risk factors leading to food and water contamination were investigated. Common pathogens isolated in stool were E. coli, E. cloacae, K. pneumoniae in food, while K. pneumoniae, Aeromonas spp. and E. cloacae were isolated from food, water and palm samples from the Maamobi and Kaneshie communities. Among the stool isolates, a total of 69.7% (85/122) Enterobacteriaceae was recovered in the study with an overall ESBL occurrence of 26.5%, predominantly among E. coli (13.2%; 10/76), Klebsiella pneumoniae (35.7%; 5/14) and Proteus mirabilis (57.1%; 4/7). Among the ESBL genes detected, blaTEM (n=14) was common, followed by blaCTX-M (n=13) and blaSHV (n=4). Thirty-four E. coli isolates from the stool samples possessed the heat labile (Lt) gene of Enterotoxigenic E. coli (ETEC) in the stool samples. All the Enterobacteriaceae isolates were resistant to the penicillins and aminoglycosides apart from E. coli which showed reduced susceptibility to both drug classes. The food items showed the common occurrence of E. cloacae (16.8%), Citrobacter spp (10.1%), E. faecalis (7.8%), Pseudomonas spp (6.7%) and K. pneumoniae (4.0%). Resistance genes and Diarrhoeagenic E. coli (DEC) showed among two C. freundii isolates possessing the blaTEM gene and one E. coli possessing the Lt gene of ETEC. Over 50% resistance to penicillins and Rifampicin among most of the Enterobacteriaceae (E. cloacae, Citrobacter spp, Aeromonas spp), and non- Enterobacteriaceae (E. faecalis) were observed among the isolates recovered. Common pathogens recovered in water and palm were K. pneumoniae, Aeromonas spp. and E. cloacae with one K. pneumoniae isolate from the palm of a food vendor possessing the blaTEM gene. Resistance to majority of the antibiotics among the Enterobacteriaceae as well as non-Enterobacteriaceae (E. faecalis and Pseudomonas spp) was observed. Mean Total Plate Counts (TPC) of 1.4 X 105 CFU/g) of unsatisfactory interpretation was observed in stew as well as mean Total Coliform Counts (TCC) of 2.2 X 105 CFU/g and 1.7 X 105 CFU/g occurring in stew and ‘waakye’ respectively. Over 50% of all water types examined for mesophilic bacteria by TPC and TCC were considered impure with all palm swabs showing a 100% purity. Environmental samples (food and water) showed the effect of non-adherence to proper hand hygiene on food and water contamination during street food vending and the need for targeted education and enforcement of food safety policies in the country. These findings confirm the existence of AMR FBPs posing a threat to food safety due to the difficult to treat infections in case of transmission. Similar resistance to beta-lactams, Tetracyclines, Azithromycin and Penicillinase antibiotics among the clinical and environmental isolates shows common FBP transmission patterns which warrants the need for more AMR integrated surveillance in the food chain prior to consumption.Item Physicochemical, Functional Properties And Mycotoxin Occurrence Of Ghanaian Tigernuts (Cyperus Esculentus L.)(University of Ghana, 2020-11) Battuta-Dawlah, S.T.ABSTRACT In Ghana, tigernut (Cyperus esculentus L.) is grossly underutilized in food applications and is mostly consumed raw as a snack. However, the soil and climate conditions of the country are conducive for cultivation of the crop on a large scale for applications in food for local consumption, industrialisation and for the export market. Food applications of tigernut and its derivatives and their possible inclusion as ingredient in the Ghanaian diet would require knowledge on its handling quality and functional properties. The aim of this study was to characterise Ghanaian tigernut as an ingredient for possible food applications. The study design consisted of two parts: (a) a cross-sectional survey of different categories of stakeholders using pre-tested semi-structured questionnaires (b) followed by laboratory designed experiments to study the quality, physicochemical and functional properties of tigernut as a function of tigernut variety and process conditions. For the surveys, a total of 1277 stakeholders in the value chain, comprising of 711 consumers and 487 traders (wholesalers/retailers) in Greater Accra region and 79 tigernut farmers in the Western and Eastern regions of Ghana, were interviewed using semi-structured researcher-administered questionnaires. The questionnaires sought to gain information on respondents’ level of knowledge on mycotoxins, as well as ascertain if measures were in place to mitigate the risk of fungal colonisation of the crop along the supply chain. Additionally, tigernuts collected at various points along the supply chain (farm, wholesale and retail) were analysed for their mycotoxin (aflatoxins and ochratoxin A) levels using reverse phase High-Performance Liquid Chromatography (HPLC), to determine the hot spots of mycotoxin contamination along the value chain. The second part of the study investigated the physical characteristics of tigernut tubers as well as the functional properties of tigernut flour with the aim of determining its suitability in food applications. Additionally, the shelf life of the tigernut flour was determined by accelerated shelf life testing using the Arrhenius model. Fresh tigernut milk is usually characterised by the sedimentation of starch which influences its flow behaviour as well as the physical stability. Furthermore, heat treatment of the milk leads to gelatinisation of the starches, which also affects the same properties. Consequently, the effects of heat (by roasting tigernuts) and adding α- amylase to the tigernut milk on the physicochemical and functional properties of tiger nut milk were studied. Tigernut oil was extracted and the phenolic and functional properties were determined as well as the effect of heat on these properties. The macro nutritional composition of tigernut tuber, flour, oil and milk were also investigated. The results of the surveys showed that tigernut farmers and consumers had appreciable knowledge in and displayed better attitude towards the prevention of mycotoxin contamination than the tigernut traders (wholesalers/retailers). The educational level of all stakeholders influenced their attitude and knowledge towards the prevention of mycotoxin contamination. Almost all consumers were willing to try new tigernut products such as the flour, oil and milk and would like to see more of these products on the Ghanaian market. The number of samples and the levels of mycotoxins (Ochratoxin A and aflatoxins) increased as the value chain progressed, with retail samples containing all the mycotoxins analysed. Total mycotoxins ranged from 0-27 μg/kg at the farm stage to 0-52 μg/kg at the wholesale stage and finally to 7.9 to 1115.48 μg/kg at the retail stage. These highlight post-harvest stage of the value chain as the focal point for mycotoxin prevention programs, although mycotoxin prevention can be agreed as a cumulative process. Both black and yellowish-brown tigernut flours contained relatively high and comparable amounts of sucrose, glucose and fructose. The relatively high resistant starch content of the tigernut flour makes the flour ideal for diabetics and weight watchers. The yellowish-brown variety had higher total starch content, higher water-retaining ability and viscosity at heating and holding cycles as compared to the black variety. Titratable acidity was found to be the crucial determinant of spoilage in tigernut flour and higher temperature was observed to increase the oxidation of the tigernut flour. This may imply that tigernut flour should be stored below room temperature. Heat and the addition of α- amylase increased the total solids, brix and titratable acidity but caused a decrease in the pH of the tigernut milk. Addition of 0.2% of α- amylase to roasted tigernut milk improved its emulsion stability. Heat and addition of α- amylase caused the tigernut milk to become darker in colour. The flow behaviour of the tigernut milk exhibited shear thinning (pseudoplastic) fluid properties. This implies that commercial production of milk from tigernut must control parameters such as speed of machines during processing as well as concentrations of food additives such as α-amylase. Chemical qualities such as iodine value, peroxide value, ester value, saponification value, free fatty acids and acid value of oil extracted from tigernut tubers, all increased at higher temperatures whilst antioxidant activity and phenolic content decreased. The functional properties of tigernut oil suggested that the oil is good for frying at lower temperatures and for shorter periods. The carbohydrate component of the tigernut tuber was mainly made up of starch and dietary fibre (resistant starches) which reduced in the milk and oil. Crude fat was the second most abundant component in the tigernut tuber. Quercetin and gallic acid were found in appreciable amounts in the tigernut oil. Although, the protein content in the tigernut milk was lower compared to the tuber, it was probably enough to impart desirable functionality to help stabilize the tigernut milk. Tigernut tuber and its derivatives can offer various options in food products. The safety of the tuber and its products can however be improved when stakeholders of the supply chain are educated and supported to implement strategies that prevent mycotoxin contamination.Item Tolerance Of Plasmodium Falciparum To Artemetherlumefantrine In The Gambia(University Of Ghana, 2020-12) Mbye, H.Antimalarial drug resistance contributes significantly to obstacles in reducing the global burden of malaria especially in sub-Saharan Africa (sSA) where the disease is most prevalent. Resistance to artemisinin-based combination therapies (ACTs), the only recommended frontline drugs for the treatment of uncomplicated malaria is now widespread in South East Asia (SEA). However, ACTs remain efficacious in sSA though in vivo delayed parasite clearance and in vitro reduced susceptibility to both components of the drug has been reported. Resistance to ACTs is therefore anticipated especially with its sustained use in endemic regions and the recent report of the emergence of de novo Pfk13 mutation that is now spreading in Rwanda. In The Gambia where artemether-lumefantrine (AL) is the first-line drug used for over 10 years, a steady increase in parasite tolerance to lumefantrine (LUM) was observed over a period of 4 years which strongly correlated with reported directional selection on a cysteine desulfarase gene (Pfnfs1). These findings are concerning and require continuous drug surveillance to track spontaneous development of AL resistant parasites and determine pathways to resistance development. This study therefore sought to investigate the prevalence and mechanisms of parasite tolerance to AL in The Gambia. A novel ex vivo drug susceptibility assay suitable to simultaneously assess parasite responses to both drugs used in AL was developed and used to assess drug susceptibility profiles of circulating parasites in western Gambia. This assay was then used to confirm identified potent compounds from the Medicines for Malaria Venture pathogen box effective against the erythrocytic stages of the parasite for future development into new antimalarial drugs. The prevalence of known drug resistance markers was assessed and novel markers that could be associated with drug resistance identified using both regression analysis and GWAS approach. Finally, CRISPR-Cas9 genome editing was used to functionally validate Pfnfs1 for its involvement in LUM tolerance using gene editing approaches. Antimalarial drug resistance contributes significantly to obstacles in reducing the global burden of malaria especially in sub-Saharan Africa (sSA) where the disease is most prevalent. Resistance to artemisinin-based combination therapies (ACTs), the only recommended frontline drugs for the treatment of uncomplicated malaria is now widespread in South East Asia (SEA). However, ACTs remain efficacious in sSA though in vivo delayed parasite clearance and in vitro reduced susceptibility to both components of the drug has been reported. Resistance to ACTs is therefore anticipated especially with its sustained use in endemic regions and the recent report of the emergence of de novo Pfk13 mutation that is now spreading in Rwanda. In The Gambia where artemether-lumefantrine (AL) is the first-line drug used for over 10 years, a steady increase in parasite tolerance to lumefantrine (LUM) was observed over a period of 4 years which strongly correlated with reported directional selection on a cysteine desulfarase gene (Pfnfs1). These findings are concerning and require continuous drug surveillance to track spontaneous development of AL resistant parasites and determine pathways to resistance development. This study therefore sought to investigate the prevalence and mechanisms of parasite tolerance to AL in The Gambia. A novel ex vivo drug susceptibility assay suitable to simultaneously assess parasite responses to both drugs used in AL was developed and used to assess drug susceptibility profiles of circulating parasites in western Gambia. This assay was then used to confirm identified potent compounds from the Medicines for Malaria Venture pathogen box effective against the erythrocytic stages of the parasite for future development into new antimalarial drugs. The prevalence of known drug resistance markers was assessed and novel markers that could be associated with drug resistance identified using both regression analysis and GWAS approach. Finally, CRISPR-Cas9 genome editing was used to functionally validate Pfnfs1 for its involvement in LUM tolerance using gene editing approaches. Keywords: Malaria, antimalarial drug resistance, ex vivo drug assays, high throughput screening genotyping, functional analysis, association studies