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Vet med hopeful

Can someone explain bovine tb and avian tb please. If the cattle is infected, why does the bovine tb create a larger lump ect... thanks

Reply 1

Lizziefickling

It's due to a type 4 hypersensitivity reaction. If a cow is already infected with TB then the cells will already be primed, therefore a lump will arise due to a cell mediated response.

You won't be expected to go into full detail as to why the reaction occurs, just know that it's a type 4 hypersensitivity reaction. The rest of it gets a bit complicated.

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Reply 2

lwescott

It's basically testing the immune system to see if it's been exposed to the Bovine TB bacterium before.

Avian and Bovine TB antigens are injected into the skin of the neck and measured with callipers 72 hours later. If the bovine injection site reacts or there is a swelling there is a cell response meaning the immune system has been previously exposed to it. The avian TB is for specificity.