this is the original paper in Nature

this is one of the key passages:

The role of badgers in the maintenance and spread of bovine TB is a matter of considerable scientific, political and public interest5, 25, 26. Owing to the absence of necessary spatial and population level data on badgers, our model does not explicitly include their role in transmission. The environmental reservoirs play a comparable function, although the contribution of reservoir species and contaminated pasture cannot be separated.

article on it in the guardian: