W Boutayeb1, M Lamlili2, A Boutayeb2. 1. Epidemiology and Bio-Mathematical Modelling, Department of Mathematics and Informatics, Faculty of Sciences, University Mohamed Ist, Oujda, Morocco. wiam.boutayeb@gmail.com. 2. Epidemiology and Bio-Mathematical Modelling, Department of Mathematics and Informatics, Faculty of Sciences, University Mohamed Ist, Oujda, Morocco.