Browsing by Author "Nyerere, Nkuba"

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A two-patch model to quantify uncertainties in the transmission of brucellosis between domestic animals
(Elsevier, 2025-09) Msuya, Rehema; Mirau, Silas; Nyerere, Nkuba; Mbalawata, Isambi
Brucellosis, a neglected zoonotic disease, poses significant health risks to both humans and livestock. This study investigates a key factor influencing brucellosis transmission: the movement of animals in and out of communal grazing areas. We develop a Continuous Time Markov Chain (CTMC) stochastic model, building on its deterministic counterpart, to assess the impact of short-term animal movements on disease transmission dynamics. By incorporating stochasticity, the model captures the inherent variability in disease transmission and animal movements, providing deeper insights than traditional deterministic models. A multitype branching process is employed to evaluate the probabilities of disease extinction. We compute the basic reproduction number and the stochastic threshold . Numerical simulations indicate that brucellosis transmission accelerates when domestic animals spend more time in high-risk communal grazing areas. Additionally, the results suggest a high probability of disease extinction when animals moves out of high-risk area. Conversely, when animals from both patches increase their time in high-risk zones, the likelihood of disease extinction diminishes. This study underscores the importance of implementing strategic movement controls and targeted interventions in high-risk areas to mitigate outbreaks and enhance disease management.
Exploring the role of funding-driven vaccination in infection dynamics of TB: A mathematical modeling approach
(Elsevier B.V., 2025-08-26) Ruojaa, Chiganga; Mayengoa, Maranya; Nyerere, Nkuba; Nyabadza, Farai
This study explores the impact of funding-driven vaccination on the transmission and spread of tuberculosis within the human population. To accurately capture the human behavior, a deterministic mathematical model is formulated, incorporating attitudes of patients towards hospital treatment. The well-posedness of the model is examined using the Lipschitz condition. An effective funding reproduction number is derived via the next-generation matrix method. Model parameters for simulation reasons are estimated by fitting to real-world data. Both theoretical and numerical findings show that decreases with increased vaccination funding and a higher proportion of patients exhibiting positive attitudes towards hospital treatment. These findings underscore the importance for policymakers to prioritize health by ensuring sufficient funding for vaccination programs, which is crucial for reducing disease burden in the community.
Mathematical model for brucellosis transmission dynamics in livestock and human populations
(Communications in Mathematical Biology and Neuroscience, 2020-01-29) Nyerere, Nkuba; Luboobi, Livingstone; Mpeshe, Saul; Shirima, Gabriel
Brucellosis is a contagious zoonotic infection caused by bacteria of genus brucella which affects humans and animals. The disease is of veterinary importance, public health concern and economic significance in both developed and developing countries. It is transmitted through direct or indirect contact with infected animals or their contaminated products. In this paper we formulate and analyze a deterministic mathematical model for the transmission dynamics of brucellosis. The model formulated incorporates contaminated environment to human, infected livestock to human, and human to human modes of transmission. The impacts of human treatment in controlling the spread of brucellosis in the human population is investigated. Both analytical and numerical solutions reveal that prolonged human treatment has a significant impact in reducing the spread of Brucellosis in human population only while elimination of the disease in domestic ruminants has promising results to both human and ruminants. Thus, brucellosis control strategies should always focus on elimination of the disease in domestic ruminants
Mathematical model for the infectiology of brucellosis with some control strategies
(BISKA Bilisim Technology, 2019-12-25) Nyerere, Nkuba; Luboobi, Livingstone; Mpeshe, Saul; Shirima, Gabriel
Brucellosis is a neglected zoonotic infection caused by gram-negative bacteria of genus brucella. In this paper, a deterministic mathematical model for the infectiology of brucellosis with vaccination of ruminants, culling of seropositive animals through slaughter, and proper environmental hygiene and sanitation is formulated and analyzed. A positive invariant region of the formulated model is established using the Box Invariance method, the effective reproduction number, Re of the model is computed using the standard next generation approach. We prove that the brucellosis free equilibrium exists, locally and globally asymptotically stable if Re < 1 while the endemic equilibrium point exists, locally and globally asymptotically stable if Re > 1. Sensitivity analysis of the effective reproductive number shows that, natural mortality rate of ruminants, recruitment rate, ruminant to ruminant transmission rate, vaccination rate, and disease induced culling rate are the most sensitive parameters and should be targeted in designing of the control strategies for the disease. Numerical simulation is done to show the variations of each subpopulation with respect to the control parameters.
Mathematical Model for the Transmission Dynamics of Bovine Tuberculosis in Human and Livestock with Control Strategies
(International Journal of Advances in Scientific Research and Engineering (ijasre), 2019-10) Sabini, Theresia Shirima; Nyerere, Nkuba; Irunde, Jacob Ismail; Kuznetsov, Dmitry
A deterministic mathematical model for bovine tuberculosis (bovine TB) in humans and livestock is formulated and used to assess the effectiveness of dairy products inspection, human treatment and quarantine of infected livestock as the control of the disease transmission. The computed effective reproduction number shows that the disease can be cleared from the population if Re is less than unity and it persists if Re is greater than unity. It means that if Re<1 the disease-free equilibrium is asymptotically stable which means the disease can be cleared from the population and endemic when Re>1 which implies the disease persists in the population. Numerical analysis was carried out to investigate how the controls can help to minimize the spread of the disease.
Mathematical model to assess the impacts of aflatoxin contamination in crops, livestock and humans
(Elsevier, 2024-03-01) Mgandu, Filimon; Nyerere, Nkuba; Mbega, Ernest; Chirove, Faraimunashe; Mirau, Silas
Aflatoxin contamination poses a significant challenge in food safety and security as it affects both the health of consumers and supply chains. Due to the health impacts associated with aflatoxin contamination, countries have set standards and restrictions for importing food crops and animal feed, resulting in greater economic losses to farmers, transporters, and crop processors. This study aimed to develop a mathematical model that tracks the contamination status of crops, livestock and humans in supporting efforts to control aflatoxin. The analysis of the mathematical model shows that both aflatoxin contamination-free equilibrium (ACFE) and aflatoxin contamination-persistence equilibrium (ACPE) exist. To study the dynamics of contamination, we derived the basic aflatoxin contamination number, 𝑅0 which is analogous to the basic reproduction number in epidemiological models. When 𝑅0 < 1, the ACFE is globally asymptotically stable, whereas when 𝑅0 > 1 the ACPE is globally asymptotically stable. Partial Rank Correlation Coefficients (PRCCs) for global sensitivity analysis were calculated using Latin Hypercube Sampling (LHS) to see how sensitive and significant the parameter is on each variable. Results from numerical simulations showed that decreasing crop contamination and shading rates and increasing the death rate of aflatoxin fungi in soil by 50% can reduce the basic contamination number by above 92%. Thus, it is important to introduce control measures that target crop contamination, shading and death rates of aflatoxin fungi in soil to reduce contamination in the population. Compared to other studies in aflatoxin contamination, the current study provides a thoroughly global sensitivity analysis of parameters involved in contamination and indicated the most important ones for control strategies
Mathematical models for the infectiology and cost-effectiveness of the control strategies for brucellosis
(NM-AIST, 2021-06) Nyerere, Nkuba
Brucellosis is a contagious zoonotic infection caused by Gram-negative bacteria of family Bru cellaceae and genus Brucella that affects humans and animals. The disease is of economic sig nificance, veterinary interest and a public health concern in most developing countries. Direct interaction among vulnerable and infectious animals or their tainted products represent the two substantial pathways for the infection conveyance. This study aimed at developing and analyz ing deterministic mathematical models for the infectiology and cost-effectiveness of Brucellosis control measures. The control mechanisms that were taken into consideration are vaccination of livestock, culling of seropositive animals by slaughtering, personal protection, and proper en vironmental hygiene and sanitation. Both analytical and numerical simulations are presented. Sensitivity analysis of the effective reproductive number revealed that the rates of livestock mor tality, recruitment, livestock to livestock transmission, vaccination and disease-driven culling are the most sensitive parameters and should be targeted in designing of the control strategies for the disease. Optimal control and cost-effectiveness analysis of the model disclosed that merging of personal protection, environmental hygiene and sanitation, progressive slaughter ing of seropositive livestock, and livestock vaccination significantly reduces infection spread in both humans and livestock at a lower cost. Additionally, seasonal weather variations have great impact on Brucellosis transmission dynamics in human, livestock and wild animals. Therefore, for the disease to be controlled or eradicated, this study recommends the timely implementation of control measures pursuant to fluctuations in disease transmission
Modeling the Impact of Seasonal Weather Variations on the Infectiology of Brucellosis
(Hindawi, 2020-10-17) Nyerere, Nkuba; Luboobi, Livingstone; Mpeshe, Saul; Shirima, Gabriel
A deterministic mathematical model for brucellosis that incorporates seasonality on direct and indirect transmission parameters for domestic ruminants, wild animals, humans, and the environment was formulated and analyzed in this paper. Both analytical and numerical simulations are presented. From this study, the findings show that variations in seasonal weather have the great impact on the transmission dynamics of brucellosis in humans, livestock, and wild animals. Thus, in order for the disease to be controlled or eliminated, measures should be timely implemented upon the fluctuation in the transmission of the disease.
Modeling the influence of fear and patients’ attitudes on the transmission dynamics of tuberculosis
(Springer Nature, 2025-01-08) Ruoja, Chiganga; Mayengo, Maranya; Nyerere, Nkuba; Nyabadza, Farai
In this study we discussed the ongoing global health challenge of tuberculosis (TB), which is caused by the Mycobacterium tuberculosis bacteria. While in several studies, the transmission dynamics of TB were examined, it is noted in this work that the impacts of social processes like disease-induced fear and patient attitudes toward hospital treatment have been receiving a poor discussion on understanding the disease transmission and its control. In this paper we present and discuss a deterministic mathematical model to investigate how these social processes influence the transmission dynamics of TB. The basic reproduction number is calculated and used to examine the stability of steady states. Additionally, we conducted a sensitivity analysis which tells what are the parameters that most significantly affect . The key findings from the analytical and numerical simulations indicate that high levels of disease-induced fear in the population, coupled with positive attitudes toward hospital treatment, can significantly reduce TB prevalence. Based on these results, the study recommends implementing control programs that address these social processes as part of the ongoing efforts to combat the TB burden.
Optimal Control Strategies for the Infectiology of Brucellosis
(Hindawi, 2020-05-11) Nyerere, Nkuba; Luboobi, Livingstone; Mpeshe, Saul; Shirima, Gabriel
Brucellosis is a zoonotic infection caused by Gram-negative bacteria of genus Brucella. The disease is of public health, veterinary, and economic significance in most of the developed and developing countries. Direct contact between susceptible and infective animals or their contaminated products are the two major routes of the disease transmission. In this paper, we investigate the impacts of controls of livestock vaccination, gradual culling through slaughter of seropositive cattle and small ruminants, environmental hygiene and sanitation, and personal protection in humans on the transmission dynamics of Brucellosis. The necessary conditions for an optimal control problem are rigorously analyzed using Pontryagin’s maximum principle. The main ambition is to minimize the spread of brucellosis disease in the community as well as the costs of control strategies. Findings showed that the effective use of livestock vaccination, gradual culling through slaughter of seropositive cattle and small ruminants, environmental hygiene and sanitation, and personal protection in humans have a significant impact in minimizing the disease spread in livestock and human populations. Moreover, cost-effectiveness analysis of the controls showed that the combination of livestock vaccination, gradual culling through slaughter, environmental sanitation, and personal protection in humans has high impact and lower cost of prevention.
Optimal Control Strategies for the Infectiology of Brucellosis
(Hindawi, 2020-05-11) Nyerere, Nkuba; Luboobi, Livingstone; Mpeshe, Saul; Shirima, Gabriel
Brucellosis is a zoonotic infection caused by Gram-negative bacteria of genus Brucella. The disease is of public health, veterinary, and economic significance in most of the developed and developing countries. Direct contact between susceptible and infective animals or their contaminated products are the two major routes of the disease transmission. In this paper, we investigate the impacts of controls of livestock vaccination, gradual culling through slaughter of seropositive cattle and small ruminants, environmental hygiene and sanitation, and personal protection in humans on the transmission dynamics of Brucellosis. The necessary conditions for an optimal control problem are rigorously analyzed using Pontryagin’s maximum principle. The main ambition is to minimize the spread of brucellosis disease in the community as well as the costs of control strategies. Findings showed that the effective use of livestock vaccination, gradual culling through slaughter of seropositive cattle and small ruminants, environmental hygiene and sanitation, and personal protection in humans have a significant impact in minimizing the disease spread in livestock and human populations. Moreover, cost-effectiveness analysis of the controls showed that the combination of livestock vaccination, gradual culling through slaughter, environmental sanitation, and personal protection in humans has high impact and lower cost of prevention.
A Review of the Mathematical Models for Brucellosis Infectiology and Control Strategies
(Journal of Mathematics and Informatics, 2020-07-21) Nyerere, Nkuba; Luboobi, Livingstone; Mpeshe, Saul; Shirima, Gabriel
Brucellosis is a zoonotic bacterial infection that can be acquired by humans from infected animals' meat, urine, body fluids, aborted materials, unpasteurized milk, and milk products or contaminated environment. Mathematical models for infectious diseases have been used as important tools in providing useful information regarding the transmission and effectiveness of the available control strategies. In this paper, a review of the available compartmental mathematical models for Brucellosis was done. The main purpose was to assess their structure, populations involved, the available control strategies and suitability in predicting the disease incidence and prevalence in different settings. Diversities have been observed in the reviewed mathematical models; some models incorporated seasonal variations in a single animal population, some ignored the contributions of the contaminated environment while others considered the cattle or sheep population only. Most of the models reviewed have not considered the contribution of wild animals in the dynamics of Brucellosis. Some models do not match the real situation in most affected areas like sub-Saharan African region and Asian countries where wild animals, cattle and small ruminants share grazing areas and water points. Thus, to avoid unreliable results, this review reveals the need to affirm and incorporate wild animals, livestock, humans and seasonal weather parameters in the spread of Brucellosis and in planning for its controls.