Badger cull? TB or not TB…

By Lauren Hoskin

During 2011, 34,000 cattle were slaughtered due to the rising problem of widespread bovine TB. This disease, which has been becoming increasingly more common in livestock across the South West over the last 20 years, is causing farmers huge losses. With rising food shortages globally this is not something we can turn a blind eye to. However, the proposal of extensive badger culls has received a lot of bad press. What many people are wondering is how badgers transmit TB to cows, would a badger cull help this problem, and what even is TB?

TB (Tuberculosis) is caused in cows by Mycobacterium bovis which is able to cause disease in farm animals, domestic animals, badgers and also humans. The bacterium primarily attacks the lungs, where it is instantly contained within a granuloma- a little sack packed full of aggressive immune cells. The immune cells close in on it, interacting with each other and trying to kill the bacteria. This containment can be successful for some time, and TB may go unnoticed in what is called a latent infection- one where the bacteria is inside the body but is momentarily stalled. However, if the immune system falters, then the granuloma will decay, releasing debris into the lungs. Dead immune cells, tissue-destroying enzymes and most importantly bacteria are coughed up, contaminating all that they touch.

It is no mystery how this deadly disease is passed back and forth between cows and badgers. Living in such close proximity, they eat, drink, urinate and defecate all on the same land. M. bovis can be disseminated through aerosols- coughs and sneezes, urine- especially high when the badger has a kidney infection, and open cuts and wounds. The cows may then pick it up through grazing on contaminated grass and water troughs.

The only vaccine available against Tuberculosis is unfortunately the bovine strain. This cannot be administered to cows seeing as it is impossible to distinguish between a vaccinated cow and a diseased cow, and BCG vaccinations in cattle are only 56%-68% effective. Randomized trials of badger culls have shown that it could reduce bovine TB up to 31.5% within the study area. Nevertheless, many are still sceptical as it is hard to estimate the number of badgers out there, and this may prove an expensive and inhumane mistake. Until a better solution is reached, however, it may be the only way….