Investigating essential factors in the spread of lassa fever dynamics through sensitivity analysis

Lassa fever is a zoonotic acute viral illness caused by Lassa virus. Since there is no vaccine yet to protect against contracting the virus, it continues to spread in West Africa. In this paper, a mathematical model of lassa transmission that considers two classes of rats: house rat and bush rat, is proposed. Theoretically, global stability of the model disease-free and endemic equilibria are established by constructing a global Lyapunov function. Sensitivity indices of the basic reproduction number are derived using the normalised forward approach to evaluate the effectiveness of control measures. The disease-free equilibrium is globally asymptotically stable when the basic reproduction number R0 < 1 and the unique endemic equilibrium is globally asymptotically stable when R0 > 1. Results from sensitivity analysis reveals that rat biting rate for infectious house rats RFH and infectious bush rats R_FB, transmission probability per contact with infectious house and bush rats (R_FH and R_FB), human recruitment rate and transmission probability per contact with infectious human hosts are highly significant in determining the severity of lassa infection. On the other hand, natural death rate of rats, natural death rate of human hosts, recovery and hospitalization rates of human hosts are critical for lassa transmission reduction. Plans that target the contact rate between house and bush rats (i.e use of indoor residual spray, fumigation of environment with pesticide) and those that target recovery rate of human hosts (i.e treatment of infectious human hosts) are recommended to control the disease.