by QueFrescoPaul » 15 Sep 2015, 08:54
E-coli is a surface bacteria, it doesn't actually grow inside the meat - that's why you can eat beef rare or blue. In other words if you cook the outside then it's safe to eat.
I don't know for certain but I guess its the same with Tuna. There may of course be other bugs in the meat but I assume that the chances of finding any are minimal because Tuna is caught wild and not farmed.
With other meats you have to cook them through to kill off other bugs which actually live in the meat rather than on the meat eg.
Chicken = Salmonella
Pork = Clostridium Botulinum, Hepatitis E
With pork it used also to be tapeworm but I believe that this has ore or less been eradicated from the food chain. You can now safely eat pork pink although you still need to have an internal temperature of 63C
Last point, these rules only apply to cuts of meat, any product formed from ground meat such as a burger or sausage must be cooked through to 75C to eradicate E-coli which could have been present on the surface of the meat before it was ground.