Browsing by Author "Mgandu, Filimon"

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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 aflatoxin contamination in crops, livestock and humans: A review
(SCIK Publishing Corporation, 2022-11-07) Mgandu, Filimon; Ngailo, Triphonia; Mugume, Isaac; Mbalawata, Isambi; Mirau, Silas
Aflatoxin is among the highest-threatening food contaminants as it affects both the health of consumers and the entire value chain. Researchers are of the view that aflatoxin contamination will increase due to the impacts of climate change. This study aimed to review studies on modelling the impacts of climate change on aflatoxin contamination to gain a deeper understanding of the progress achieved, methodologies used and potential gaps or opportunities for further studies. A critical analysis of the available literature revealed that aflatoxin contamination is a spatial-temporal phenomenon as it depends on both location and time. In many regions, data unavailability has been an obstacle in developing predictive models. We note that it is necessary for each region to have their own models according to the crop, soil characteristics and projected climate of the given area for better and more accurate results. Future studies should focus on the first; surveillance of susceptible crops and gathering of aflatoxin contamination data. Second, developing models to assess the aflatoxin contamination risk due to projected climate change, soil properties, and crop characteristics so that proper strategies can be adopted. Third, laboratory experimental results must be validated in fields to increase their usability.
Modelling the transmission dynamics and control of aflatoxins crops and its associated health risks in livestock and humans
(NM-AIST, 2024-07) Mgandu, Filimon
Aflatoxin contamination poses a significant challenge to food safety and security, as it affects both the health of consumers and the entire supply chain. Doses of aflatoxins beyond accept able levels are dangerous and may lead to poisoning, also called aflatoxicosis, a life-threatening illness. Liver damage or liver cancer, especially for people who may have conditions such as hepatitis B infection, is also caused by aflatoxin consumption. This study aimed to investigate the transmission dynamics and control of aflatoxin contamination in crops and its associated health risks in livestock, and humans. A deterministic mathematical model to study transmis sion dynamics was formulated and analyzed. Partial Rank Correlation Coefficients (PRCCs) for global sensitivity analysis were calculated using Latin Hypercube Sampling (LHS) to de termine how sensitive and significant the parameters are for each variable. Three controls, namely good farming practices, biological control, and public education and awareness cam paigns, were analyzed. The optimal control theory and cost-effective analysis were performed to identify the most effective strategy for aflatoxin contamination mitigation in crops, live stock, and humans. Four machine learning algorithms: Gaussian Process Classification (GPC), Support Vector Machine (SVM), Random Forest Classifier (RFC), and K Nearest Neighbors (KNN) have been used to predict aflatoxin contamination in maize and groundnuts. The anal ysis of the mathematical model formulated shows that aflatoxin contamination-free equilib rium (ACFE) and aflatoxin contamination-persistence equilibrium (ACPE) exist. The ACFE is globally asymptotically stable if the basic aflatoxin contamination number R0 < 1 whereas the ACPE is globally asymptotically stable if R0 > 1. Numerical simulations showed that a decrease in crop contamination and shedding rates and an increase in the death rate of aflatoxin fungi in the environment by 50% reduced the basic contamination number by above 92%. Re sults from the optimal control analysis suggest that implementation of all controls performs better than other strategies in controlling aflatoxin contamination in crops, livestock, and hu mans. Therefore, to control aflatoxin contamination, initiatives should focus on good farming practices, biological control, and public education and awareness campaigns. In predicting aflatoxin contamination, GPC outperformed other models with an accuracy of 96% and 95% in groundnut and maize samples, respectively. Moreover, the study revealed that humidity and rainfall have a greater influence on predicting aflatoxin contamination compared to tempera ture.
Optimal control and cost effectiveness analysis of contamination associated with aflatoxins in maize kernels, livestock and humans
(Elsevier, 2023-12) Mgandu, Filimon; Mirau, S; Nyerere, N; Chirove, F
Aflatoxin contamination poses a significant challenge in food safety and security as it affects both health of consumers and supply chains. Due to 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. Three controls, namely good farming practices, biological control and public education and awareness campaigns, have been mostly used in countries where aflatoxin contamination has occurred. Since resources are scarce, there is a need to find the optimal and cost-effective strategy to reduce the burden on farmers. This study aimed to find optimal and cost-effective control strategy to mitigated aflatoxin contamination in maize kernels, livestock and humans. A deterministic model was developed and analyzed for studying the impact of implementing three time dependent controls on the dynamics and control of aflatoxin contamination in maize kernels, livestock and humans. We use optimal control theory to find the necessary conditions for existence of the optimal controls and to determine the optimal strategy for controlling the aflatoxin contamination. We also carry out cost-effectiveness analysis through Incremental Cost Effective Ratio (ICER) to obtain the most effective strategy. Simulation results for the optimal control problem suggest that strategy which involve implementation of all controls performs well than other strategies in controlling the aflatoxin contamination in maize kernels, livestock and humans. Therefore, to control aflatoxin contamination initiatives should focus on good farming practices, biological control and public education and awareness campaigns.