Why are badgers and TB a new problem?

Readers answer other readers' questions on subjects ranging from trivial flights of fancy to profound scientific concepts
Have badgers always posed a TB threat? Photograph: Alamy

Farmers have been keeping cattle outdoors for centuries, and badgers have been around all that time - so why is TB seemingly a new problem? I don't remember hearing about it years ago. What happened in the 19th century? Was there any remedy? Or am I missing something?

Jill Bennett, St Albans, Herts

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