Browse
Recent Submissions
Item An Intrinsic Analysis of Human Brucellosis Dynamics in Africa(ResearchGate, 2022-08-27) Lolika, Paride O.; Helikumi, MlyashimbiBrucellosis is one of the most common zoonotic infections globally. It affects humans, domestic animals and wildlife. In this paper, we conduct an intrinsic analysis of human brucellosis dynamics in non-periodic and periodic environments. As such we propose and study two mathematical models for human brucellosis transmission and control, in which humans acquire infection from cattle and wildlife. The first model is an autonomous dynamical system and the second is a non-autonomous dynamical system in which the seasonal transmission of brucellosis is incorporated. Disease intervention strategies incorporated in this study are cattle vaccination, culling of infectious cattle and human treatment. For both models we conduct both epidemic and endemic analysis, with a focus on the threshold dynamics characterized by the basic reproduction numbers. Using sensitivity analysis we established that R0 is most sensitive to the rate of brucellosis transmission from buffalos to cattle, the result suggest that in order to control human brucellosis there is a need to control cattle infection. Based on our models, we also formulate an optimal control problem with cattle vaccination and culling of infectious cattle as control functions. Using reasonable parameter values, numerical simulations of the optimal control demonstrate the possibility of reducing brucellosis incidence in humans, wildlife and cattle, within a finite time horizon, for both periodic and non-periodic environments.Item Global Stability Analysis of a Fractional-Order Ebola Epidemic Model with Control Strategies(2024-02-13) Lolika, Paride O; Helikumi, Mlyashimbi; Jomah, Sulieman A. S; Bakhet, Mohamed Y. A.; Galla, Kennedy Crispo; Kheiralla, Awad HussienWe proposed a fractional-order derivative model for Ebola virus disease (EVD) to assess the effects of control strategies on the spread of the disease in the population. The proposed model incorporates all relevant biological factors, health education campaigns, prevention measures, and treatment as control strategies. We computed the basic reproduction number R0 and qualitatively used it to assess the existence of the model states. In particular, we noted that two equilibrium points exist, the disease-free and endemic equilibrium points which are both globally stable whenever R0 < 1 and R0 > 1 respectively. We performed sensitivity analysis on the key parameters that drive the EVD dynamics to determine their relative importance in EVD transmission and prevalence. Model parameters were estimated using the 2014 Ebola outbreak in Guinea. Further, numerical simulation results are presented using fractional Adam-Bashforth-Moulton scheme to support the analytical findings. From the numerical simulations, we have noted that as α decreases from unit, the solution profiles of the model attain its stability much faster than at α = 1. Furthermore, the results demonstrated that the aforementioned control strategies have the potential to reduce the transmission of EVD in the population.Item Existence of Maximal and Minimal Solutions Initial Value Problem for The System of Fractal Differential Equations(Springer, 2025) Sajid,Mohammad; Kalita,Hemanta; Zengin, Gülizar Gülenay; Wangwe, LucasDifferential equation refers to an equation that includes a function and its derivatives. These equations serve to model real-world situations where rates of change are significant. They are classified as either ordinary differential equations (ODEs) or partial differential equations (PDEs), depending on whether the unknown function is dependent on one or several independent variables, respectively. This paper presents a thorough investigation into fractal differential inequalities linked with an initial value fractal differential equation. It establishes the existence of a solution to this equation and demonstrates the convergence of both minimal and maximal solutions. Additionally, the paper introduces a comparative principle for evaluating solutions to the initial value problem associated with the fractal differential equation, ensuring a detailed and rigorous analysis of this subject.Item Comparative evaluation of antimicrobial activity and synergistic effects of selected Tanzanian medicinal plants against urinary tract infection pathogens(South African Journal of Botany, 2025-07-30) Mwalongo, Optatus; Kisula, Lydia; Credo, David; Sauli, ElingaramiThe emergence of microbial resistance towards existing drugs for treating UTIs seriously threatens public health worldwide, thus necessitating the search for alternative antimicrobial agents, particularly from medicinal plants. This study determined the standalone in vitro antimicrobial activity of ethanolic extracts from Ocimum gratissi- mum, Sida acuta, Lantana camara, Plectranthus barbatus, Tridax procumbens, and Euphorbia hirta against selected non-antimicrobial-resistant (AMR) and AMR uropathogens (bacterial strains and Candida albicans). Among these, Plectranthus barbatus, Euphorbia hirta, and Lantana camara exhibited the highest antimicrobial efficacy. Subse- quently, their synergistic interactions were determined against the same test microbes. Plant materials were extracted using 80% ethanol via a maceration technique. The antimicrobial efficacy of the individual and combined extracts was evaluated by broth microdilution against standard and clinical isolate microbial strains, namely Escherichia coli ATCC25922, Klebsiella pneumoniae K6 ATCC700603, Staphylococcus aureus ATCC25923, Methicillin-resistant Staphylococcus aureus (MRSA, WHO control), Enterococcus faecalis ATCC29212, Candida albicans NR29341 and clinical isolate Klebsiella pneumoniae, while a checkerboard microdilution assay was employed to assess the combined extracts’ interaction. Results revealed that all the individual plant extracts significantly inhibited the growth of the test microorganisms with varying efficacy [F (5, 36) = 2.48, η² = 0.8, p = 0.002]. The minimum inhibitory concentration (MIC) values ranged from 0.31 to 6.67 mg/mL. Of the six tested plant extracts, P. barbatus and E. hirta were highly effective against all tested microbes. The combined extracts exhibited significantly higher antimicrobial activity than individual extracts against all tested microbes [t (46.74) = -6.49, Cohen’s d = 1.4, p < 0.001]. Furthermore, the analysis of interaction types among combined extracts demonstrated that double and triple crude extract combinations exhibited partial synergy, additive and indifferent effects. Thus, this study demonstratesItem Global Dynamics of Fractional-order Model for Malaria Disease Transmission(Asian Research Journal of Mathematics, 2022-07-09) Helikumi, Mlyashimbi; Lolika, Paride O.In this study, we formulated and analyzed a fractional-order model for malaria disease transmission using Atangana-Beleanu-Caputo in sense to study the effects of heterogeneity vector biting exposure on the human population. To capture effects the heterogeneity vector biting exposure, we sub-divided the human population into two sub-groups namely; the population in high and low risk areas. In the model analysis, we computed the basic reproduction number R0 and qualitatively used to assess the existence and extinction of disease in the population. Additionally, we used the fixed point theorem to prove the existence and uniqueness of solutions.Numerical schemes for both Euler and Adam-Bathforth-Moulton are present in details and used in model simulations. Furthermore, we performed the numerical simulation to support the analytical results in this study. From numerical simulations, we estimated the values of model parameters using least square fitting method for the real data of malaria reported in Zimbabwe. The sensitivity analysis of the model parameters was done to determine the correlation between model parameters and R0. Finally, we used the Euler and Adam-Bashforth-Moulton scheme to simulate the model system using estimated parameters. Overall, we noted that fractional-order derivatives have more influence on the dynamics of malaria disease in the populationItem Dynamics and Analysis of Chronic Brucellosis in Sheep(Journal of Advances in Mathematics and Computer Science, 2020-08-30) Lolika, Paride O.; Helikumi, MlyashimbiWe proposed and studied a new fractional-order model for the transmission dynamics of brucellosis with a special focus on the sheep-to-sheep transmission. Two control strategies namely; culling and vaccination rate are incorporated in the model. We computed the basic reproduction number R0 and we studied the global stability of disease-free and endemic equilibrium point in terms of basic reproduction number R0. We found that both the disease-free and endemic equilibrium points are globally stable whenever R0 < 1 and R0 > 1 respectively. In numerical simulations, we performed the sensitivity analysis of the model and expressed the relationship between model parameters and R0. We noted that, increase on the magnitude of model parameters with negative correlation coefficients would significantly reduce the spread of Brucellosis disease in the population. Moreover, model validation and parameter estimation for fractional-order and classical integer-order derivatives was carried out using real brucellosis for Egypt, 1999-2011. Overall, we noted that fractional-order model gave better prediction of brucellosis compared to classical integer-order model. Furthermore, we investigated the role of memory effects on the transmission of brucellosis in the population. We observe that, the memory effects have influence on the transmission of brucellosis in the community. In addition, we noted that the aforementioned control strategies have the potential to reduce the transmission of brucellosis in the population. In particular, we observed that whenever the culling and vaccination rate is greater than 40% and 50% respectively, the disease dies out in the population.Item Optimal Control Applied to a Stage-Structured Cassava Mosaic Disease Model With Vector Feeding Behavior(Elsevier, 2025-01-05) Lusekelo, Eva; Helikumi Mlyashimbi; Mushayabasa, Steady; Mushayabasa, SteadyCassava remains Sub-Saharan Africa’s second most crucial staple food crop after maize. However, production of sufficient yields is hampered by pests and diseases. In particular, the whitefly (Bemisia tabaci) has the potential to reduce expected yields by 50% since it directly damages cassava leaves by feeding on phloem, causing chlorosis and abscission. This study develops a novel mathematical model for cassava mosaic disease that incorporates immature and adult whitefly populations. Additionally, the model includes vector feeding behavior since prior studies have shown that vectors exhibit preferences to settle for either healthy or infected hosts. We determined the offspring number and carried out its sensitivity analysis. Additionally, we carried out an optimal control study on the use of insecticides and plant roguing as disease control measures against cassava mosaic disease. Our results show that vector preference and efficiency of disease control strategies plays an important role in shaping the short and long- term dynamics of cassava mosaic disease, which subsequently impacts the design of its optimal control strategiesItem Dynamics and Analysis of COVID-19 Disease Transmission: The Effect of Vaccination and Quarantine(AIMS, 2023-09-01) Helikumi, Mlyashimbi.; Lolika, Paride O.In this study, a fractional-order model for COVID-19 disease transmission is proposed and studied. First, the disease-free equilibrium and the basic reproduction number, R0 of the model has been communicated. The local and global stability of the disease-free equilibrium have been proved using well-constructed Lyapunov functions. Moreover, a normalized sensitivity analysis for the model parameters has been performed to identify their influence on R0. Real data on COVID-19 disease from Wuhan in China has been used to validate the proposed model. Finally, a simulation of the model has been performed to determine the effects of memory and control strategies. Overall, one can note that vaccination and quarantine have the potential to minimize the spread of COVID-19 in the population.Item Invasive Argemone mexicana’s suppressive effects on Phaseolus vulgaris and Zea mays germination and growth(bioRXiv, 2023) Ojija, FredrickInvasive Argemone mexicana plant species is invading many ecosystems in East Africa. However, there have not been many studies to assess how it affects plants. In petri dishes and pot experiments, we investigated the suppressive effects of A. mexicana on Phaseolus vulgaris and Zea mays germination and seedling growth. To investigate its suppressive effects on the test plant, different concentrations of A. mexicana leaf (AmL) crude extract were applied to the seeds and seedlings of P. vulgaris and Z. mays. At higher concentrations (70% and 100%), the findings showed that AmL crude extract concentrations reduced the germination and growth of P. vulgaris and Z. mays seeds. Compared to seeds that germinated at lower concentrations and in the control (0%) group, fewer seeds at higher concentrations grew. Accordingly, higher concentrations, relative to lower ones and controls, retarded seed germination. Additionally, the fresh biomass, root lengths, stem diameters, and heights of P. vulgaris seedlings were reduced under 75% and 100% AmL concentrations, which had a negative impact on their growth vigor. Although this study shows that P. vulgaris and Z. mays germination and growth were inhibited by A. mexicana crude extract, field research experiments are needed to investigate the suppressive effects of this invasive weed on other plant species. Due to its detrimental impact on plant growth, the study recommends further management of A. mexicana to protect biodiversity. It is expected that these results will be helpful in developing policies and programs for managing invasive plants while taking into account the effects on people’s livelihoodsItem Macro Invertebrates as Bio Indicators of Water Quality in Nzovwe Stream, in Mbeya, Tanzania(JSTR, 2016-06-06) Ojija,Fredrick.; Laizer, Hudson.This study was carried out to assess the water quality of Nzovwe stream using macroinvertebrates as bioindicators. Biological monitoring working party (BMWP) scoring system was the index used to assess the ecosystem health of Nzovwe stream. A total of 584 aquatic macroinvertebrates were identified from Nzovwe stream. They belonged to 22 families. The most abundant taxa were Odonata (35.959%), Hemiptera (25.514%), Coleoptera (18.493%), and Diptera (12.842%). Whereas the least abundant taxa were Ephemeroptera and Gastropoda, each constituting 1.028% of all macroinvertebrates. The most abundant macroinvertebrates were Dragonflies (27.226%), Water striders (13.185%), and Creeping water bugs (10.274%), whereas the least abundant were Giant water bugs (0.514%) and Backswimmers (0.514%). The BMWP score of Nzovwe stream was 115. Based on this score, the water of Nzovwe stream is neither very clean nor significantly altered aquatic environment. Hence the Nzovwe stream is moderately polluted due to non-point source pollution from several sources. Moreover, it was found that agricultural activities, washing and bathing could alter physico-chemical parameters of the stream and hence changing the abundance of macroinvertebrates as well as the quality of water. This study, therefore, recommends that the source of pollutants should be controlled and the stream regularly monitored by the relevant authorities. Additionally, biological indicators and their indices are suggested to be used in assessing the condition of a stream ecosystem.Item Ecology and Influence of Age and Habitats on the Diurnal Activity Patterns of Cattle Egret (Bubulcus Ibis)(INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH, 2025) Ojija, FredrickIt was found that habitat types and age may influence diurnal activities of cattle egrets. In average, the grassland comprised 41.59% of all of diurnal activities, while forest and bushland comprised 21.54% and 35.79% of all of diurnal activities respectively (P0.05). The adult cattle egrets spent much time feeding than sub-adults and juveniles. The feeding behaviour was the diurnal activity of cattle egrets performed most often in the morning hours. The diurnal activity patterns and time budgets of the cattle egrets may be due to their strategies to cope with environmental factors such temperatures, different habitats and food availability; and high foraging behaviour can be due to high energy demand.Item Diversity and Abundance of Arthropods at Mbeya University of Science and Technology, Tanzania(IJSTR, 2016-09-09) Ojija, FredrickDespite the high abundance of arthropods in many terrestrial environments, our understanding of their ecological diversity and abundance remain unknown in some habitats. The aim of this study is to assess the abundance, diversity and species richness of some arthropods found in grassland and woodland habitats at Mbeya University of Science and Technology in Tanzania. A total of 1719 arthropods belonging to 63 species under 12 orders and 46 families were collected. Parameters such as Shannon index, Simpson index, Margalef index, Evenness index and Sorenson similarity index were used to analyse the diversity of arthropods. Result showed that, Hymenoptera (33.101%), Coleoptera (28.098%) and Orthoptera (17.510%) were the most dominant orders, whereas the least abundant order were Diptera (0.814%) and Scolopendromorpha (0.291%). The grassland showed high species richness, Margalef index (D = 6.930), abundance (n = 1177), Evenness (E = 0.854) and Shannon diversity (H = 3.339) of arthropods. The abundance of arthropod groups between grassland and woodland differed significantly (p<0.05). Sorensen similarity index in both habitats showed 53.5% similarity. Therefore, result indicates that the grassland habitat has the potential to support arthropod diversity and act as effective refugia for some arthropods from woodland.Item Effect of Global Climate Change on Insect Populations, Distribution, and its Dynamics(ELSEVIER, 2025-07-07) Ojija, Fredrick; Mng’ong’o, Marco; Aloo, Becky N.; Mayengo, Gabriel; Helikumi, MlyashimbiInsects are vital to various ecosystems as pollinators, decomposers, and food sources for many organisms. They dominate diverse terrestrial (e.g., glassland) and aquatic (lakes, oceans, rivers, etc.) ecosystems. Previous studies report that more than half of the estimated 2.0 million species of living organisms identified on our planet are insects. However, global climate change (GCC), characterised by rising temperatures and altered precipitation patterns, significantly impacts their populations worldwide. We reviewed the literature to provide an overview of GCC events in insects. Collectively, the study findings reveal that global temperature and precipitation change are among the extreme GCC events affecting more than 30% of insect population, distribution, physiology, feeding habits, interactions, migration, and communication across the globe. The climate change intensifies insect cycles and insect damage in agroecosystems. In response, insect species alter their geographic ranges and phenology, changing population dynamics and interactions. GCC also influences reproductive patterns, including mating behaviour and breeding synchrony. Warmer global temperatures might advance or delay insect emer- gence, causing mismatches with food availability or pollination partners. While some insect populations may adapt, extreme heat events or prolonged droughts exceeding their physiological tolerance result in population declines or local extinctions. Predictions suggest that up to 65% of insect populations could face extinction within the next century due to increasing climate change. Thus, understanding these impacts is essential for predicting the ecological consequences of the GCC and developing effective conservation strategies to mitigate such impacts and protect insect biodiversity and ecosystem servicesItem Allelopathic Effects of Sphaeranthus Suaveolens (Forssk.) DC. and Argemone Mexicana L Leaf Crude Extract On Zea Mays L Germination and Growth(ResearchGate, 2023) Ojija, FredrickSphaeranthus suaveolens (Forssk.) DC. and Argemone mexicana L. plant species are agricultural weeds that threaten crops and native plant diversity in East Africa, particularly in Tanzania. Yet, there have been few studies to assess whether their allelopathic effects inhibit plant germination and growth. Experiments were carried out in petri dishes and pots to investigate the inhibition effects (here referred to as negative allelopathy) of S. suaveolens leaf (SsL) and A. mexicana leaf (AmL) crude extracts on Zea mays L germination and seedling growth. Zea mays seeds and seedlings were treated with different crude concentrations of SsL and AmL to investigate their inhibition potential. The results showed that SsL and AmL crude extract concentrations delayed and/or reduced Z. mays germination, particularly at higher concentrations (70% and 100%). At these higher concentrations, few seeds germinated compared to the number of seeds germinated at lower concentrations (0%, 25%, and 50%). Further, it was found that Z. mays growth vigour was negatively affected as evinced by lower stem and root lengths, diameters, and total fresh biomass at higher concentrations of SsL and AmL. Although this study demonstrates the allelopathic effect of S. suaveolens and A. mexicana on Z. mays germination and growth, it also recommends further laboratory and field research experiments to investigate their allelopathic effects on other crops and native plants. However, this study advises that the management and control of these weeds be taken into account as their inhibitory effects could subsequently lead to a loss of plant diversity and crop productivity.Item A Preliminary Study on Abundance and Diversity of Aquatic Macro Invertebrates of Nzovwe Stream, in Mbeya, Tanzania(Research Publish Journals, 2016) Ojija, Fredrick; Kavishe, ReganThe purpose of this current study was to determine the diversity, species richness, dominance and evenness of macroinvertebrates fauna found in Nzovwe stream. The study was carried out from 02 November to 28 December 2015. A total of 584 aquatic macroinvertebrate from 7 orders and 16 species were recoded. They belonged to 22 families. This study shows that Odonata (35.96%) was the most dominant order according to total number of individuals, followed by Hemiptera (25.514%), Coleoptera (19.007 %), Diptera (12.842%), Plecoptera (5.137%), Gastropoda (1.027%) and Ephemeroptera (1.027%). The most abundant species were Dragonflies (27.226%), Water striders (13.185%), and Creeping water bugs (10.274%), whereas the least abundant species were Giant water bugs and Backswimmers (0.514%). The Shannon-Wiener Index diversity and Evenness index (Pielou’s index) was higher in order Coleoptera (1.33) and Diptera (0.940) respectively. Ephemeroptera, Plecoptera and Gastropoda (Shannon’s, H’ = 0.00) were the lowest. Simpson’s Reciprocal Index diversity was highest in order Coleoptera (3.400) while Ephemeroptera, Plecoptera and Gastropoda (1/D = 1.000) were the lowest. The species richness of macroinvertebrates was calculated by using Margalef’s Index. Moreover, it was found that the stream is poorly managed and threatened by pollution from domestic wastes.Item Assessment of Current State and Impact of REDD+ on Livelihood of Local People in Rungwe District, Tanzania(Forest Research Open Access, 2016-01-18) Fredrick, OjijaA climate change mitigation mechanism, Reducing Emission from Deforestation and forest Degradation (REDD+) is anticipated to affect livelihoods of forest dependent communities. This study was conducted to establish this impact on livelihoods of local people in Rungwe District, Tanzania. Data were collected through questionnaires, group discussions, and interviews from three villages: Syukula, Ilolo and Kibisi. Results showed that households annual income and crop production are higher after REDD+ implementation. The older respondents (> 40 years old) considered REDD+ to be important for forest management compared to younger generation (<40 years old) (p< 0.05). Similarly, the older respondents considered wood forest products such as fuelwood, charcoal, timber and poles to be reduced. There was a widespread awareness about REDD+’s objectives among household respondents. Therefore, REDD+ proponents should implement alternative sources of livelihoods to help local people improve their income and reduce dependence on the forest resources and eventually decrease deforestation and forest degradation.Item A CommonFixed Point Theorem for Generalised F-Kannan Mapping in Metric Space with Applications(Hindawi, 2021) Wangwe, Lucas; Kumar, SantoshThis paper is aimed at proving a common fixed point theorem for F-Kannan mappings in metric spaces with an application to integral equations. The main result of the paper will extend and generalise the recent existing fixed point results in the literature. Wealso provided illustrative examples and some applications to integral equation, nonlinear fractional differential equation, and ordinary differential equation for damped forced oscillations to support the resultsItem Fixed point and common fixed point theorems for (ƴ S q)-F-Contraction mappings in b-Metric like spaces with Application.(European Journal of Mathematics and Applications, 2023) Wangwe, LucasThis paper proves some fixed point theorems for (ƴ s q )F- Kannan mappings and A common fixed point Theorem for (ƴ S q)-F- Reich type contraction mappings In a b-Metric Like space. Finally, We give an application to the solvability of a non linear integral equation.Item The Role of Rhizobia toward Food Production, Food and Soil Security Through Microbial Agro-input Utilization in Developing Countries(Elsevier, 2023-06-17) Mng’ong’o, Marco E; Ojija, Fredrick; Aloo, Becky N.Agricultural inputs such as fertilizers are becoming increasingly expensive and less available in developing countries, leading to decreased land productivity and food availability. Similarly, over-dependence on inorganic fertilizers and pesticides not only increases production costs but also poses a threat to the environment. Hence, alternatives to traditional agricultural inputs are necessary to achieve sustainable land productivity while maintaining environmental quality. Nitrogen (N)-fixing bacteria (rhizobia) are a group of plant growth- promoting bacteria that live in symbiosis with legumes. Their interaction with legume roots results in nodules that provide plants with additional nutrients through N-fixation, making legumes ideal crops due to reduced N fertilizer requirements. Despite their potential to improve land productivity and increase food production and security, the use of rhizobia is limited in developing countries due to limited research and agricultural microbial product production. Therefore, additional efforts are needed to increase the utilization of soil microbes to ensure food and soil security. The present review expounds on the role of rhizobia toward food production, food and soil security through microbial agro-input utilization in developing countries. Included in the review are the diversity of root-nodulating rhizobia, morphology and formation of legume, the role of nodulating bacteria for increased food production in developing countries, the application of nodulating bacterial technologies in food production in developing countries, and the implication of nodulating bacteria toward agricultural sustainability in devel oping countries. The review established that rhizobia are less utilized in developing countries as an option to increase food production and soil security due to limited research and agricultural microbial agro-input product production. Thus, additional efforts are required to increase soil microbes utilization to increase food production and ensure food security.Item ARGEMONE MEXICANA’S LEAF CRUDE EXTRACT SUPPRESSES PHASEOLUS VULGARIS AND ZEA MAYS GERMINATION AND GROWTH(Tropical Agroecosystems, 2023) Ojija, FredrickThe Argemone mexicana plant species is invading many habitats in Tanzania. Nevertheless, there have not been many studies to assess how it affects crops. In petri dishes and pot experiments, we investigated the suppressive effects of A. mexicana on Phaseolus vulgaris and Zea mays germination and seedling growth. Different concentrations of A. mexicana leaf (AmL) crude extract was applied to the seeds and seedlings of P. vulgaris and Z. mays. At higher concentrations (>70%), AmL crude extract concentrations reduced the germination and growth of P. vulgaris and Z. mays seeds. The fresh biomass, root lengths, stem diameters, and heights of P. vulgaris seedlings were reduced at higher concentrations (>75%) of AmL, which had a negative impact on their growth vigour. Although this study shows that P. vulgaris and Z. mays germination and growth were inhibited by A. mexicana crude extract, field research experiments should investigate the suppressive effects of this invasive weed on native plant species. The study recommends further management of A. mexicana to protect native biodiversity. It is expected that these results will be helpful in developing policies and programs for managing invasive plants while taking into account the effects on people's livelihoods.