Bio security - an effective alternative to badger culling

I have always been puzzled as to how badgers are supposed to infect cattle with bovine tuberculosis (bTB) given that the main method of disease transmission is via exhaled breath. The number of occasions that a cow breaths in breath exhaled by a badger must be very low compared to the number of times that they breath in breath from another cow.

I was therefore very interested to read this letter in The Times (paywall) by Emeritus Professor of Epidemiology of Infectious Diseases Keith Neal (ignore the headline - this reflects the second letter). He says that the disease can also be passed in faeces and urine but:

• cows are unlikely to eat badger faeces
• urine quickly soaks into the ground

making direct disease transmission via these extremely unlikely.

He suspects that badger to cattle transmission may be caused by badgers getting into places where cattle food is stored and urinating on the food. He points out that the best way to stop this transmission id by better bio security (to stop badgers getting into such places) but that this requires expenditure by farmers.

In other areas of the world in which bTB has been reduced, such as Ireland, there has been a emphasis on improving bio security, among other measures.