The Mathematical Modelling of Crimean Congo Haemorrhagic Fever Disease: An Approach Based on SIRD Model

Crimean-Congo haemorrhagic fever (CCHF) is a life-threatening zoonotic disease endemic in Turkey. It is transmitted mainly through tick bites and human-to-human contact, and is characterised by a high case fatality rate. The first case was seen in the Kelkit valley and the first diagnosis was made in 2003. The disease is more common in provinces such as Tokat, Sivas, Yozgat, Erzincan and Gümüşhane where the Kelkit valley passes. Sivas has become an experienced center that deals with patients coming from these surrounding provinces. In this study, the transmission dynamics of CCHF were investigated through a Susceptible-Infected-Recovered-Dead (SIRD) compartment model formulated as a system of ordinary differential equations and calibrated using epidemiological data collected from Sivas Cumhuriyet University Research Hospital between 2010 and 2024. The model parameters, including the transmission rate β, recovery rate γ, disease-induced mortality rate α and natural mortality rate µ, were estimated from real data. The basic reproductive number (R0), which is used to determine the potential for an outbreak of disease, was derived using the next generation matrix method. Local stability analyses of disease-free and endemic equilibrium points were performed by examining the eigenvalues of the Jacobian matrix using the Routh-Hurwitz criterion. The assessment of global stability was conducted by the construction of an appropriate Lyapunov function. Sensitivity analyses were conducted to ascertain the impact of parameter variation on R0. Numerical simulations implemented in MATLAB demonstrated the temporal evolution of the epidemic under varying initial conditions and parameter sets. The incorporation of mortality data within the SIR framework yielded a more realistic data.