Abstract
Lassa fever, caused by the Lassa virus, remains a critical public health concern in Nigeria. In this research,
we employed mathematical modeling to comprehensively analyze the dynamics of Lassa fever within the
Nigerian population. We presented three distinct mathematical models tailored to the context of Lassa
fever. Firstly, we investigated the transmission dynamics of Lassa fever in the presence of multiple transmission
pathways. Secondly, we explored the use of community pathogen load modeling approach to
study the dynamics of infection incorporating intervention strategies and applied optimal control theory to
assess the effectiveness of these interventions. Lastly, we contrasted deterministic and stochastic models
with environmental variability to understand the impact of randomness on Lassa fever dynamics, and establish
conditions for extinction or persistence. The research employs exploratory data analysis to uncover
hidden patterns in Lassa fever data from Nigeria, providing valuable insights. The mathematical models
were analyzed to find steady states and the basic reproduction number R0, in addition to global stability
and bifurcation analysis. Effective intervention strategies were introduced and analyzed using the Pontryagin
Maximum Principle. The models were parameterized using Lassa fever data in Nigeria, offering
empirical support for their structures. Additionally, a continuous-time Markov chain model was developed
to capture the disease’s behavior, and the probability of Lassa fever persistence and extinction within the
population was calculated. The results of the study show that multiple intervention strategies should be
targeted at various routes of infection since a combination of infection transmission pathways is associated
with additional increase of Lassa virus in the population. Since the community pathogen load contribution
from the human, rodent and virus populations cannot be curbed using one control measure, resources can
be distributed in a particular ratio so that every control strategy will be accounted for. The study also
highlighted the conditions for pathogen extinction or persistence and a sensitivity analysis undertaken to
illustrate the relationship between transmission rates and the probability of pathogen extinction.
Keywords: Lassa · Optimal control · Community Pathogen Load · Mathematical model · Basic reproduction
number · Sensitivity analysis · Model fitting · Stochasticity · Branching process.