Professor Malcolm Bennett: “Pasteurisation of milk has largely got rid of bovine TB in people in the UK”
Malcolm Bennett is Professor of Veterinary Pathology in the University of Liverpool’s Institute of Infection and Global Health
“Cattle that test positive for TB are usually caught early during infection using a skin test that measures the immune response rather than a direct test for infection. This is because it is very difficult to detect the bacteria until the animal becomes clinically ill, and because we want to diagnose and remove cattle from the population as early as possible and before they have the chance to infect other cattle.
Minimise risk of transmission
“The test-positive cattle are slaughtered at the end of the working day to minimise any risk of transmission or contamination, and like all carcasses, those of test-positive cattle are inspected for any signs of diseases that could stop the meat going off for human consumption: indeed these cattle are subject to extra scrutiny.
“If there is no TB lesion, or only one site of TB lesions, then the affected organ is removed and the rest of the carcass goes off for human consumption. If more than one site of TB is identified, however, which would suggest spread of disease, the whole carcass is condemned.
“The bacteria don’t grow very well in muscle, so the risk of infection from traditional meat is lower still, and the bacteria are readily killed by cooking. The main risk is likely to be to people who handle infected/contaminated carcasses – and this is a well-recognised risk for American hunters handling venison, for example.
“Back when bovine TB was a huge public health problem, as it still is in some developing countries, the main source of human infection was drinking unpasteurised milk. The combination of controlling TB in cattle and, particularly, pasteurisation of milk has largely got rid of bovine TB in people in the UK. The few cases that are diagnosed each year are either imported cases or reactivations of infections from long ago or, occasionally, from drinking unpasteurised milk.
“So the risk of getting TB from eating meat from these cattle is very low – and the FSA have stated that they know of no examples of this ever happening.
“I think that this is an argument about risk and differing perceptions of what is acceptable and what is not. In this case the argument has been muddied by the controversy over the control of bovine TB and in particular the role of badgers in the epidemiology of bovine TB.
Argument muddied
“Currently bovine TB is not a significant public health issue in the UK, because we pasteurise most of our milk. Rather it is a problem of animal health and farming economics, of international trade agreements, of biosecurity and ecology, and of party politics.
“There is potential damage to public health should pasteurisation not work or the epidemic in cattle get even more out of hand than it currently is, but eating meat from reactor cattle is rather a diversion from more important aspects of the debate.”
For more on this story visit: http://www.telegraph.co.uk/earth/earthnews/10151399/Bovine-TB-in-milk-as-well-as-beef.html
