Dr. John Griffin:

Traditionally, the belief about TB was that it was transmitted animal to animal directly. That is still the case. As to how far it can be transmitted, it is a short distance. For example, the UK’s Department for Environment, Food and Rural Affairs recommends that, if a farmer has a neighbour whose animals have tuberculosis, the farmer should set an electric fence 3 m inside. That should be sufficient to prevent nose-to-nose transmission.

There has been a change in recent years, in that there is much more evidence now of indirect transmission of tuberculosis. Pasture or troughs can become contaminated. There is not a great deal of evidence that badgers come into direct contact with cattle to a major extent. Likewise with deer.