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ItemAssessment of mosquito repellent efficacy of different formulations from tithonia diversifolia, cymbopogon citratus, and eucalyptus globulus(Makerere University, 2026)Mosquito-borne diseases remain a major public health concern, particularly in sub-Saharan Africa. Growing limitations of synthetic repellents including resistance, environmental concerns, and safety issues have increased interest in plant-based alternatives. This study evaluated the repellent efficacy of essential oil formulations from T. diversifolia, C. citratus, and E. globulus against anopheles gambiae mosquitoes. Plant essential oils extracted via hydro-distillation, were characterized using FTIR and GC–MS for 1,8-cineole in E. globulus citral in C. citratus, and d-limonene in T. diversifolia. Individual essential oils were tested at 12% ,15% and 18%v/v test concentrations of the main active repellent compounds. Three Polyherbal blend formulations; Blend A (12%), Blend B (15%), and Blend C (18%) were prepared using the minimum effective concentrations of T. diversifolia (15%), C. citratus (12%), and E. globulus (12%). Repellency efficacy of the individual oils versus the blended formulations against Anopheles gambiae was assessed following the Surface Landing method with Odomos and methanol as the positive control and negative control respectively. At 12%, Blend A maintained 89.0 ± 2.0% repellency at 4 h and 15.0 ± 0.2% at 8 h, compared with 01EO (59.0 ± 1.4%, 1.0 ± 0.0%), 02EO (88.7 ± 1.6%, 11.0 ± 0.0%), and 03EO (83.1 ± 1.7%, 10.0 ± 1.5%), with significant differences for 01EO at all time points and with 02EO and 03EO at later hours (p < 0.05). At 15%, Blend B retained 82.4 ± 1.5% and 78.0 ± 2.0% repellency at 5–6 h and 20.2 ± 0.5% at 8 h, exceeding 01EO (86.6 ± 1.8%, 73.3 ± 0.0%, 10.0 ± 0.0%), 02EO (85.0 ± 1.6%, 72.8 ± 1.5%, 15.0 ± 1.7%), and 03EO with significant differences for all individual oils at later hours (p < 0.01-0.001). At 18%, Blend C maintained 96.4 ± 2.5%, 86.0 ± 1.0%, and 60.0 ± 0.5% repellency at 5, 6, and 8 h, respectively, compared with 01EO (68.0 ± 1.6%, 36.0 ± 1.6%, 10.0 ± 1.4%), 02EO (90.0 ± 0.0%, 83.3 ± 1.7%, 30.0 ± 0.0%), and 03EO (89.0 ± 1.7%, 80.2 ± 1.7%, 40.0 ± 1.9%), with Blend C significantly outperforming all oils at most time points (p < 0.05-0.001). Findings from this study indicate that blends are more effective than individual oils and show that potential synergistic blending significantly improves both potency and duration.
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ItemDevelopment and evaluation of loop-mediated isothermal amplification assays for diagnosis of malaria and sickle cell anaemia(Makerere University, 2026)Malaria and sickle cell anaemia (SCA) are co-endemic and are among the leading cause of child morbidity and mortality in Uganda. Misdiagnosis of malaria and delayed diagnosis of SCA due to low parasite density and lack of diagnostic facilities at the point of care leads to poor case management. This study developed Loop-mediated isothermal amplification (LAMP) assays for diagnosis of malaria and SCA with the aim of improving the diagnosis of both malaria and SCA at the point of care. The LAMP assay primer sets targeting the Plasmodium falciparum plasmoredoxin (Plrx) gene and the SCA rs334 mutation were designed. The LAMP assays were optimized and their diagnostic performance were evaluated in terms of sensitivity and specificity using blood samples from consented participants. The Plrx based LAMP assay for diagnosis of malaria had a limit of detection of 7 parasites/µL, analytical specificity of 100% and a turnaround time of 30 minutes when DNA is available. The Plrx based LAMP assay had a diagnostic sensitivity of 100% and specificity of 95%, with an almost perfect agreement (κ = 0.929) compared to nested Polymerase chain reaction when performed on 127 blood samples. The SCA rs334 mutation based LAMP assay for diagnosis of SCA had analytical sensitivity of 0.2 ng/µL and failed to accurately differentiate all the rs334 mutations and wild type alleles. The SCA LAMP assay had a turnaround time of 60 minutes, diagnostic sensitivity and specificity of 100% and 64.3% respectively. The Plrx LAMP assay and SCA LAMP assay developed in this study are simple, rapid and require less sophisticated dry heat block and are therefore, good options to be applied at the point of care.
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ItemLarvicidal potency of plectranthus barbatus, Andr. Labiatae on some culicine and anopheline mosquitoes(Makerere University, 1998)For a long time, plectranthus barbatus Andr. (Labiatae), a dicotyledonous shrub has been used successfully by the Luo people in Eastern Uganda as a mosquito repellent by placing it’s branches in windows. This act, implies that P. barbatus has mosquitocidal properties, which were investigated in this study with a major objective of finding out whether or not this plan contained bioactive compounds against mosquitoes. Samples of the plant were collected from Tororo District and separated into floral, leaf and stem portions. Following methods described by Odyek et al. (1989), cold extraction was carried out using ether, methanol and water. Crude extracts obtained, were tested for their toxicity against shrimp, mosquito larvae and adults, using bench to bioassay guided screenings, recommended for dose-effect experiments. Results obtained were analysed using Finney’s subprogram and three factor Analysis of Variance which was recommended in reviews cited by Simpson et al (1960). Examination of results obtained from the shrimp assay indicated significant bioactivity within the leaf and stem methanolic crude extracts. However, only ether crude extracts were found significantly bioactive against mosquito larvae. Floral and leaf ether crude extracts exhibited the highest activity against all mosquito larvae (LSD value 12.73; 10.75, p=0.05, 2df) unlike the stem extract (LSD value 6.78, p=0.05, 2df). Larval response varied among species with higher mortalities in Anopheles and Culex (LSD values respectively = 11.87; 11.22, p=0.05, 2df) unlike Aedes (LSD value 7.159, p=0.05, 2df). LD50 values obtained also agreed with the above results confirming that floral and leaf crude extracts of P.borbatus are significantly toxic to Culex, Aedes and Anopheles mosquito larvae unlike the stem extracts. All the ether crude extracts obtained did not exhibit toxic or repellent properties to Culex, Aedes and Anopheles adult mosquitoes. This contradicated with the indigenous knowledge and use of the plant by the Luo people in Eat Uganda, as a mosquito repellent. It was thus deduced that P.barbatus contains useful larvicidal coumpounds which could be isolated and identified.
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ItemDiversity and distribution of amphibian fauna within wetland ecosystems in greater Kampala City, Uganda(Makerere University, 2025)Urbanisation is an important global driver of biodiversity change, negatively impacting some species groups whilst providing opportunities for others. Like most cities, Kampala is constantly expanding, thus altering most natural ecosystems including wetlands. The extent to which biodiversity is impacted by urbanisation depends on its intensity, the spatial scale, and the taxonomic group studied. Increasing urbanisation of greater Kampala areas comes with a cost to wetlands, resulting in direct impacts such as filling, drainage, and excavation, as well as indirect impacts caused by, for example, changes in hydrology, releases of pollutants, and introductions of non-native plants and animals. This generates great heterogeneity in habitats that affects relatively immobile animals, such as reptiles and amphibians (herpetofauna) as they become isolated at best and obliterated at worst. However, studies that evaluate effect of human activities on amphibians in the Kampala-metropolitan area are very scanty. This study focused on three wetlands that are in close proximity to the city center: Lubigi, Kinawataka and Kira. An urban-rural gradient was adopted, and sampling was done using Visual Encounter Survey technique between March and July, 2018. Three transects in each wetland were established and sampled twice. With exception of vegetation height and water depth, all the other habitat variables were visually estimated. Shannon-Weiner index was used to assess differences in species diversity among the wetlands. Relationship between amphibian species, wetland characteristics and intensity of land use types was determined using non-metric multidimensional Scaling (NMDS) ordination methods. In total, 1297 individuals belonging to 15 species were recorded by this study. Lubigi wetland had significantly higher proportion of amphibians, followed by Kiira and least Kinawataka. The urban wetlands had significantly lower numbers of amphibians compared to the peri-urban sites. Family Hyperolidae was the most dominant followed by Pyxicephalidae, Ptychadenidae, Bufonidae, and least was hrynobatrachidae. Four species that are considered nationally Data Deficient were recorded by this study. The different land-use types affected amphibian species abundance differently. Also, different species were not uniformly associated with the environmental variables assessed. These findings indicate that the remnant wetlands still support an array of amphibians and therefore there is need to consider herpetofauna in urban planning.
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ItemRichness and distribution of Benthic Macroinvertebrates in selected waterbodies, Uganda(Makerere University, 2025)Benthic macroinvertebrates are important in the functioning of freshwater ecosystems, as they regulate primary production, cleanse water, decompose organic matter, translocate materials in water, form key links in food webs, and are invaluable indicators of stream degradation. However, most of the biological conservation measures present are for other groups of aquatic organisms, like vertebrates, with limited measures present for macro-invertebrates. Legislative and institutional shortcomings regarding the protection of benthic macroinvertebrates in Uganda pose a severe threat to their protection, for they exacerbate the effects of the primary threats of pollution and habitat loss by failing to provide robust and enforceable mechanisms for their conservation and effective monitoring. The Legislative and institutional shortcomings are due to lack of organized and centralized macroinvertebrate data which hinders evidence-based policymaking and adaptive management. This study aimed at contributing information leading to the development of the first national checklist of benthic macroinvertebrates in Uganda, so as to provide reference baseline information for guiding conservation and sustainable use of aquatic ecosystems in the country. To achieve this, the study mobilized data on occurrence records from datasets available in Global Biodiversity Information Facility (GBIF), archives of biodiversity surveys conducted at the National Fisheries Resources Research Institute (NaFIRRI) in Uganda, and publications of benthic macroinvertebrate studies done in Uganda. A total of 9860 records of benthic macro-invertebrates were retrieved from 65 waterbodies, with 85% of the records from the major lakes namely: Victoria, Kyoga, Albert, George and Edward, and with 15% from the minor/satellite water bodies in the country. This study also revealed that the macroinvertebrates in the country belong to five phyla namely; Annelida, Arthropoda, Mollusca, Nematoda, and Platyhelminthes, with majority of the records belonging to Phylum Arthropoda, and Nematoda and Platyhelminthes having the least records. Also, majority (58%) of the records were identified to Genus level. In terms of diversity, more families were recorded in large waterbodies, with Victoria basin having higher taxa richness. For the records identified to species level, majority of the species with known conservation status were found to be of least concern status hence are not under threat. The study also revealed that the environmental variables that predict maroinvertebrate assemblages in Ugandan water bodies are: DO, SRP, salinity, SRSI, conductivity, SD, Turbidity, Salin, TSS, pH, NO2, Chla, TP, TN, TD, Temperature, and NH4. Regarding hotspots for biodiversity conservation at broader taxonomic levels (phylum and class), extensive systems like the Kibale swamp-river system and Lake Albert exhibited the highest diversity. At family level however, the Bwindi Impenetrable National Park rivers emerged as a unique hotspot with highest of level diversity. Also, the high proportion (58%) of geographically restricted macroinvertebrate families in Uganda indicates that Uganda's waters host many rare macroinvertebrate families. This indicates that they are extremely vulnerable, and those specific waterbodies need immediate protection to ensure these indigenous species survive. Also, the high number of Not Evaluated (NE) species (highest in Lake Victoria) points to significant knowledge gaps in basic taxonomic assessment of benthic macroinvertebrates in the country.