Osong Public Health and Research Perspectives

Original Articles

A Differential Equation Model for the Dynamics of Youth Gambling: Tae Sug Do, Young S. Lee; Osong Public Health Res Perspect. 2014;5(4):233-241. Published online August 31, 2014; DOI: https://doi.org/10.1016/j.phrp.2014.06.008

Abstract PDF: Objectives
We examine the dynamics of gambling among young people aged 16–24 years, how prevalence rates of at-risk gambling and problem gambling change as adolescents enter young adulthood, and prevention and control strategies.
Methods
A simple epidemiological model is created using ordinary nonlinear differential equations, and a threshold condition that spreads gambling is identified through stability analysis. We estimate all the model parameters using a longitudinal prevalence study by Winters, Stinchfield, and Botzet to run numerical simulations. Parameters to which the system is most sensitive are isolated using sensitivity analysis.
Results
Problem gambling is endemic among young people, with a steady prevalence of approximately 4–5%. The prevalence of problem gambling is lower in young adults aged 18–24 years than in adolescents aged 16–18 years. At-risk gambling among young adults has increased. The parameters to which the system is most sensitive correspond to primary prevention.
Conclusion
Prevention and control strategies for gambling should involve school education. A mathematical model that includes the effect of early exposure to gambling would be helpful if a longitudinal study can provide data in the future.

Role of Active and Inactive Cytotoxic Immune Response in Human Immunodeficiency Virus Dynamics: Hernan Dario Toro Zapata, Angelica Graciela Caicedo Casso, Derdei Bichara, Sunmi Lee; Osong Public Health Res Perspect. 2014;5(1):3-8. Published online February 28, 2014; DOI: https://doi.org/10.1016/j.phrp.2014.01.001

Abstract PDF: Objectives
Mathematical models can be helpful to understand the complex dynamics of human immunodeficiency virus infection within a host. Most of work has studied the interactions of host responses and virus in the presence of active cytotoxic immune cells, which decay to zero when there is no virus. However, recent research highlights that cytotoxic immune cells can be inactive but never be depleted.
Methods
We propose a mathematical model to investigate the human immunodeficiency virus dynamics in the presence of both active and inactive cytotoxic immune cells within a host. We explore the impact of the immune responses on the dynamics of human immunodeficiency virus infection under different disease stages.
Results
Standard mathematical and numerical analyses are presented for this new model. Specifically, the basic reproduction number is computed and local and global stability analyses are discussed.
Conclusion
Our results can give helpful insights when designing more effective drug schedules in the presence of active and inactive immune responses.

A Note on Obesity as Epidemic in Korea: Mun Seok Kim, Chaeshin Chu, Yongkuk Kim; Osong Public Health Res Perspect. 2011;2(2):135-140. Published online June 30, 2011; DOI: https://doi.org/10.1016/j.phrp.2011.08.004

Abstract PDF: Objective To analyze the incidence of obesity in adults aged 19–59 years in Korea and predict its trend in the future.
Methods
We considered a two-compartmental deterministic mathematical model Susceptible-Infected-Susceptible (SIS), a system of difference equations, to predict the evolution of obesity in the population and to propose strategies to reduce its incidence.
Results
The prevention strategy on normal-weight individuals produced a greater improvement than that produced by treatment strategies.
Conclusions
Mathematical model sensitivity analysis suggests that obesity prevention strategies are more effective than obesity treatment strategies in controlling the increase of adult obesity in Korea.

Mathematical Modeling of Vibrio vulnificus Infection in Korea and the Influence of Global Warming: Chaeshin Chu, Younghae Do, Yongkuk Kim, Yasuhisa Saito, Sun-Dong Lee, Haemo Park, Jong-Koo Lee; Osong Public Health Res Perspect. 2011;2(1):51-58. Published online June 30, 2011; DOI: https://doi.org/10.1016/j.phrp.2011.05.002

Abstract PDF: Objectives
To investigate the possible link between Vibrio vulnificus population size in seawater and water temperature.
Methods
We collected incidence and water temperature data in coastal regions of Korea and constructed a mathematical model that consisted of three classes; susceptible fish, infected fish available to humans, and infected humans.
Results
We developed a mathematical model to connect V. vulnificus incidence with water temperature using estimated bacterial population sizes and actual coastal water temperatures.
Conclusion
Increased V. vulnificus population sizes in marine environments may increase the risk of infection in people who eat at coastal restaurants in Korea. Furthermore, we estimated the near-future number of infected patients using our model, which will help to establish a public-health policy to reduce the disease burden.

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