A cow would have to be infected with the disease. Now to explain, there are very strict rules and laws in place. Since the outbreak in the UK many years ago. Food can be traced back to its source these days. There are regular checks done on places that meat is coming from. As in the animals before they are slaughtered. Rules and laws are very tight. Would be a long shot to catch it. Just another fear your mind has created like the HIV fear you had for years.