Mathematical modeling of acute and chronic leptospirosis transmission considering multiple susceptibility risk

Leptospirosis is an emerging zoonotic disease that poses significant public health and economic challenges. In this paper, we analyze the dynamics of leptospirosis disease considering acute and chronic leptospirosis transmission with varying level of risk. We analyzed the qualitative behavior of the model, focusing on the positivity and boundedness of the system. To assess how well the model represents reality, we calibrated it using actual leptospirosis case data from Kerala, spanning from June 2022 to December 2023. This calibration guarantees that the model provides a faithful and dependable representation of the epidemiological dynamics observed in the specified region over the given time-frame. A comprehensive global stability analysis is carried out for the disease-free state of the proposed model, with respect to the basic reproduction number (R₀). The normalized forward sensitivity analysis of R₀ indicates that reducing the disease transmission rates is critical for effective disease control. In addition, sensitivity and uncertainty analyses are performed to determine the most influential parameters governing disease transmission. The Partial Rank Correlation Coefficient (PRCC) approach supported by scatter plot visualization, is employed to evaluate and illustrate the global sensitivity of the model parameters. Our numerical simulations suggest that the high-risk population is particularly vulnerable to both acute and chronic leptospirosis infections, exhibiting higher infection peaks and prolonged disease persistence.