Browsing by Author "Trazias, Herman"

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    Dynamical modeling of Salmonellosis in humans and dairy cattle with temperature and pH effects
    (Elsevier Ltd., 2025-03) Trazias, Herman; Mayengo, Maranya; Irunde, Jacob; Kgosimore, Moatlhodi
    Approximately 20 million cases and 0.15 million human fatalities worldwide each year are caused by Salmonellosis. A mechanistic compartmental model based on ordinary differential equations is proposed to evaluate the effects of temperature and pH on the transmission dynamics of Salmonellosis. The transmission potential of the disease in areas with temperature and pH stresses is examined. The next-generation matrix method is applied to compute the temperature-pH-dependent reproduction number . The dynamical regimes of the system are examined using Lyapunov stability theory and backward bifurcation analysis. The uncertainty and global sensitivity analysis are examined using the Latin Hypercube Sampling (LHS) and Partial Rank Correlation Coefficient (PRCC) methods. The numerical simulations of the proposed model under favorable and unfavorable temperatures are performed with a confidence interval (CI) for the reliability assessment of the model parameters. The analysis shows that the ingestion rates of Salmonella enterica subsp. enterica serovar Typhimurium bacteria in humans and dairy cattle, human-to-human transmission rate, cattle-to-cattle transmission rate, human shedding rate, dairy cattle shedding rate, and the rate of producing contaminated dairy products are directly proportional to the number of infected humans and infected dairy cattle. The temperature ranges of and and pHs greater than 3.8 have a significant effect on the dynamics of Salmonellosis. In order to eliminate Salmonellosis, the study recommends treating natural water bodies using the recommended chemical disinfectants during summer seasons and in areas with temperature ranges of , cooking food at the hottest temperatures, and storing food at the lowest temperatures for all pHs.
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    Modeling salmonellosis transmission dynamics in humans and dairy cattle with optimal controls
    (Elsevier, 2025-02) Trazias, Herman; Irunde, Jacob; Kgosimore, Moatlhodi; Mayengo, Maranya
    In this paper, we develop a mathematical model to examine the transmission dynamics and control analysis of salmonellosis in humans and dairy cattle. The model considers three time-dependent controls (improving hygiene, vaccination, and organic acid disinfectants), human and dairy cattle populations, and Salmonella typhimurium bacteria in the environments and dairy products. The next generation matrix technique is applied to compute the effective reproduction number that gauges the persistence and extinction of salmonellosis while adopting the proposed control interventions. The stability behavior of the equilibrium states is examined using the Lypunov function method based on the effective reproduction number . The Latin hypercube sampling and the partial rank correlation coefficient methods are used to investigate the sensitivity and uncertainty of input parameters against model outputs. The results indicate that improving hygiene and vaccination can eliminate salmonellosis. Improving hygiene habits at a rate of at least 0.9 per day is recommended to eliminate salmonellosis. An efficacious vaccine that can immunize at least 85% of the vaccinated dairy cattle is also recommended to eradicate salmonellosis if it can be implemented to vaccinate susceptible dairy cattle at a rate of at least 0.45 per day for the first 30 days of the salmonellosis outbreak. The use of all three controls is recommended to eliminate salmonellosis quickly and at the lowest cost.