Modelling Population Behaviour

This thesis formulates novel mathematical models that integrate human behavioural dynamics. Through mathematical modelling, the thesis studies the evolution of large-scale populations in the context of i) the spread of recurrent epidemic diseases, ii) sexually transmitted infections (STIs), and iii) climate change. This thesis explores factors that positively impact population behaviour, including health-protective behaviour during epidemics (Chapters 3–5), condom use for STI prevention (Chapter 6), and environmentally responsible behaviour in the context of climate change (Chapters 7 and 8).

We study the effect of testing campaigns, vaccination campaigns, and physical distancing behaviour on infection prevalence and local outbreak control. We analytically derive conditions under which local outbreaks will be extinguished. If these conditions are not satisfied, the disease becomes endemic, and we compute the infection prevalence at the endemic equilibrium. For successful local outbreak control, our results emphasise the importance of testing campaigns and responsible population behaviour. Vaccination campaigns are crucial in alleviating hospital strain by decreasing the prevalence of individuals with severe symptoms. Additionally, we demonstrate that risk perception significantly influences epidemic spread. Under certain conditions and high levels of risk perception, there are periodic epidemic outbreaks.