Browsing by Author "Lusekelo, Eva"

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    Modelling campylobacteriosis dynamics: Impacts of contaminated animal products and environmental decontamination interventions
    (ELSEVIER, 2025-09-09) Trazias, Herman; Lusekelo, Eva; Sakran, Abass Kasim
    Campylobacteriosis is responsible for approximately 500 million cases of illness globally each year. Globally, human campylobacteriosis infections and contaminated animal products cause an estimated loss of 8.6 and 12.6 billion US dollars annually, respectively. The disease is transmitted through consumption of contaminated foods and water, licking unsanitary hands and contact with infected hosts. As global demand for animal products like meat and milk continues to grow, the transmission of campylobacteriosis through these products has become a critical concern. This study aims at utilising mathematical modelling and analysis techniques to quantify the effects of contaminated animal products and environmental decontamination interventions on campylobacteriosis dynamics in host populations. A mathematical model as a system of ordinary differential equations is proposed with human and cattle populations and contaminated animal products. The next-generation matrix method is applied to compute the effective reproduction number  that describes disease persistence and extinction. The global stability of equilibria states is examined using the Lyapunov stability theory. The uncertainty and sensitivity of model parameters are examined using the Latin Hypercube Sampling and Partial Rank Correlation Coefficient methods. Model fitting and parameter estimations are performed using the least squares method alongside the human cases from January to August for the years 2017 to 2020 in the EU. The analysis indicates that the disease-free and endemic equilibria are globally asymptotically stable whenever  < 1 and  > 1, respectively. The numerical results show that the ingestion rates of contaminated animal products, shedding rates and the natural replication rates of Campylobacter jejuni bacteria are directly proportional to , while the environmental cleanliness and the decay rate of Campylobacter jejuni bacteria are inversely proportional to . In order to reduce the impact of contaminated animal products, the study recommends a couple of strategies for reducing shedding rates, killing bacteria, and vaccinating infected hosts.
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    Modelling Campylobacteriosis Dynamics: Impacts of Contaminated Animal Products and Environmental Decontamination Interventions
    (ELSEVIER, 2025-09-01) Trazias, Herman; Lusekelo, Eva; Abass, Kasim Sakran
    Campylobacteriosis is responsible for approximately 500 million cases of illness globally each year. Globally, human campylobacteriosis infections and contaminated animal products cause an estimated loss of 8.6 and 12.6 billion US dollars annually, respectively. The disease is transmitted through consumption of contaminated foods and water, licking unsanitary hands and contact with infected hosts. As global demand for animal products like meat and milk continues to grow, the transmission of campylobacteriosis through these products has become a critical concern. This study aims at utilising mathematical modelling and analysis techniques to quantify the effects of contaminated animal products and environmental decontamination interventions on campylobacteriosis dynamics in host populations. A mathematical model as a system of ordinary differential equations is proposed with human and cattle populations and contaminated animal products. The next-generation matrix method is applied to compute the effective reproduction number  that describes disease persistence and extinction. The global stability of equilibria states is examined using the Lyapunov stability theory. The uncertainty and sensitivity of model parameters are examined using the Latin Hypercube Sampling and Partial Rank Correlation Coefficient methods. Model fitting and parameter estimations are performed using the least squares method alongside the human cases from January to August for the years 2017 to 2020 in the EU. The analysis indicates that the disease-free and endemic equilibria are globally asymptotically stable whenever  < 1 and  > 1, respectively. The numerical results show that the ingestion rates of contaminated animal products, shedding rates and the natural replication rates of Campylobacter jejuni bacteria are directly proportional to , while the environmental cleanliness and the decay rate of Campylobacter jejuni bacteria are inversely proportional to . In order to reduce the impact of contaminated animal products, the study recommends a couple of strategies for reducing shedding rates, killing bacteria, and vaccinating infected hosts.
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    Optimal Control Applied to a Stage-structured Cassava Mosaic Disease Model with Vector Feeding Behavior
    (ELSEVIER, 2025) Lusekelo, Eva; Helikumi, Mlyashimbi; Daudi, Salamida; Mushayabasa, Steady
    Cassava remains Sub-Saharan Africa’s secondmost crucial staple food crop after maize. However production of sufficient yields is hampered by pests and diseases. In particular, the white fly (Bemisia tabaci)has the potential toreduceexpectedyieldsby50%since it directly damages cassava leaves by feeding on phloem, causing chlorosis and abscission. This study develops an ovel mathematical model for cassava mosaic disease that incorporates immature and adult white fly populations. Additionally, the model includes vector feeding behavior since priorstudieshaveshownthatvectorsexhibitpreferencestosettleforeitherhealthyorinfected hosts.Wedeterminedtheoffspringnumberandcarriedoutitssensitivityanalysis.Additionally, we carried out an optimal control study on the use of insecticides and plantroguing 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 strategies
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    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, Steady
    Cassava 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 strategies