This work describes the mathematical modelling and dynamics of a novel Coronavirus disease 2019 (COVID-19) in Kenya. The mathematical model assumes Human-Human infection as well as Human-Pathogen interaction. Using the SEIR (Susceptible-Exposed-Infected-Recovered) compartmental model with additional component of the pathogen,we simulated the dynamics of COVID-19 outbreak and impact of different control measures. The resulting system of ordinary differential equations (ODEs) are directly solved using a combination of fourth and fifth-order Runge-Kutta methods. Simulation results indicate that non-pharmaceutical measures such as school closure, social distancing and movement restriction emphatically flatten the epidemic peak curve hence leading to a smaller number of overall disease cases.