There are many methods that are designed in  softwares to  model mathematical functions for a natural phenomenon with given boundary restrictions. See the following article entitled:"Modeling Biology Spanning Different Scales: An Open Challenge" by

Filippo Castiglione et. al. In this article, it is coming nowadays more clear that in order to obtain a unified description of the different mechanisms governing the behavior and causality relations among the various parts of a living system, the development of comprehensive computational and mathematical models at different space and time scales is required. This is one of the most formidable challenges of modern biology characterized by the availability of huge amount of high throughput measurements. In this paper we draw attention to the importance of multiscale modeling in the framework of studies of biological systems in general and of the immune system in particular. See the full article at the link:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4124842/

I hope this helps.

Thank you for your answer!

I  would like to see the economic effects of diseases and find a mathematical model

in order to simulate the spread of the disease in an area with a specific

animal population. Allocating economic losses to the

sick animals I could make an economic simulation.