Did you freeze the meat for over 2 weeks?  I suggest a cut of meat rather than "hamburger" meat.  I remember reading something along the lines that after around 1982 hamburger came from many different cows, and that the old meat was safer.  I would get steak, freeze it, then after over 2 weeks, cut it into small pieces, though as I said I'm not sure about the blood.  Did you do anything to drain the blood before preparing it?

Another idea is to just eat the middle of the steak that is not cooked, but you probably won't know if that animal was in good health.  However, one clear difference is that when you grind up all that meat, even if it is from all healthy animals, you are exposing it to air, light, and who knows what else, and so eating the raw middle of a steak is likely to be a better idea, and also don't be frugal with the salt.  The problem with salt is that if you use a lot of it and eat the wrong fats, but don't consume enough potassium and/or antioxidant-rich foods, you can have hypertension problems.  I do both, using a little potassium chloride mixed in with my salt, and also eating antioxidant-rich foods with each meal (and very little unsaturated fatty acids).  Let me know if you experience anythying interesting.