Q&A: TB in meat
Diseased cattle, slaughtered after testing positive for bovine tuberculosis (bTB), are being sold for human consumption by Defra, the government department responsible for food. Should we be concerned?
What is bovine TB?
Bovine TB (bTB) is an infectious disease that mainly affects cattle. It is similar to tuberculosis that affects humans, in that it is caused by a bacterium. BTB can be passed from infected animals to humans through close contact and ingestion of unpasteurised milk and meat from infected animals. If this happens, the symptoms are much the same as with regular TB - persistent cough, breathlessness and weight loss.
Is it safe to eat beef?
The Food Standards Agency says there is no known case of anyone contracting bTB from eating meat. All meat, including that from cattle slaughtered due to bTB, must undergo rigorous food safety checks before being passed as fit for consumption. As a result, the risk is extremely low.
The bacteria that cause TB don't grow very well in muscle, so the risk of infection from traditional meat is lower still, and TB bacteria are readily killed by cooking.
Charles Milne, from the Food Standards Agency in Scotland, says he's confident about the safety of the meat: "Certainly I would be more than content to eat any carcasses that had been through meat inspection and passed. One has to remember that the infection tends to be in parts of the carcass that are not consumed, so it's very, very rare that you would find infection in meat itself."
And Prof Nigel Brown, President of the Society for General Microbiology, said: "I would be happy to eat meat from TB-infected cattle, and people should not be unduly concerned.
"One of the main reasons for TB testing of cattle is to eliminate TB from dairy herds, as it is possible to catch TB from infected, unpasteurised milk. Cows may be milked before their TB infection is known, and I strongly recommend that people do not drink raw milk."
How is meat checked?
All meat goes through a number of safety checks.
Cattle with bTB are most often identified through testing using the tuberculin skin test before they develop obvious signs of the disease. This is because the disease usually progresses slowly and it can take some time for clinical signs to appear.
If an inspection of a carcass reveals bTB infection in more than one organ or region it is declared unfit for human consumption and destroyed.
But if only one part of the carcass is infected - the lungs, for example - that part is removed and the rest is considered fit for consumption.
Could it be in my burgers?
The meat in question is banned by most supermarkets, but it is sold by some caterers and food processors. This means, potentially, some schools, hospitals and care homes in the UK may serve it up. There is no requirement to label meat to say that it has come from a TB-infected animal.
How many people have caught bTB?
The number of human TB cases due to M.bovis infection is closely monitored by Public Health England, Public Health Wales and Health Protection Scotland. Overall, human TB caused by M.bovis accounts for less than 1% of the total TB cases diagnosed in the UK every year. Each year, there are around 40 cases of humans catching bTB. This compares with 9,000 cases of regular human TB. If you work closely with livestock and/or regularly drink unpasteurised (raw) milk you have a greater risk of exposure.