Modeling the effects of screening, vaccination, treatment, and non-pharmaceutical controls on leptospirosis transmission dynamics

Abstract

Leptospirosis is the world’s most common zoonotic disease and remains a significant public health challenge, particularly in regions with poor sanitation and high exposure risks. This study aims to evaluate the effectiveness of combined interventions: screening, vaccination, treatment, and non-pharmaceutical controls in reducing leptospirosis transmission in human and domestic animal populations. The study develops and analyzes a deterministic compartmental model with eleven compartments representing human, domestic animal, and bacterial populations. Stability analysis reveals that the Disease-Free Equilibrium (DEF) is globally asymptotically stable when the effective reproduction number is less than a unit ( < 1), ensuring disease eradication under these conditions, whereas the Endemic Equilibrium Point (EEP) remains stable when > 1. The study employs the normalized forward sensitivity index to determine the most influential parameters affecting disease dynamics and shows that an increase in the transmission of infections from a contaminated environment to susceptible domestic animals, transmission of infections from a contaminated environment to susceptible humans, contact between infected animals and susceptible humans, and contact among domestic animals ( ), respectively with humans recruitment rate (), significantly contributes to a higher basic reproduction number , leading to a higher induced infection rate as more people become infected. While parameters related to bacterial decay natural mortality rates (), and disease-induced mortality were found to be negatively influencing . Furthermore, numerical simulations demonstrate that implementing a combination of screening, vaccination, treatment, and non-pharmaceutical interventions substantially reduces the reproduction number and disease prevalence compared to implementing single interventions. The findings emphasize that controlling leptospirosis requires an integrated, multi-faceted strategy, including environmental sanitation, reservoir control, fencing, the use of proper protective equipment (PPE), and public health education to reduce exposure risks. The study provides a robust mathematical foundation to support policymakers in developing integrated public health strategies aimed at achieving long-term disease reduction.