Some issues on the mathematical modeling of population dynamics using differential equations

Mathematical modeling is a useful and widely used method in epidemiology. The paper highlights a number of mistakes or issues in the formulation of the previous population models using differential equations. The issues are the lack of mathematical models of Non-Communicable Diseases (NCDs), the wrongly formulated mathematical terms, the absence of time delay and the ill-posedness of governing equations. Finally, some brief results of a preliminary study which addresses the issues, is provided.