Derek Brown explains. The latest figures indeed look alarming. A total of 443 outbreaks were reported in England in 1997. In the first nine months of last year, there were 637. In Great Britain as a whole, the corresponding figures are 515 and 745.
Nobody knows for sure.
There are various theories about how myobacterium bovis spreads. Some say is passed from animal to animal through contact. Some say is airborne or that it lurks in the soil. Farmers are strongly inclined to blame badgers, which harbour the same disease. That theory first emerged in the early 1970s.