In "this day and age" meat, when properly handled, is cleaner than ever. Sushi or other raw meat is handled very carefully by highly trained chefs--and meat itself is, internally sterile. Parasites and other food poisoning buggies come from surface contamination.
Considering how well people treat horses--I'd imagine horse-meat is not unsafe at all. Considering also the fact that Japan has a significantly higher average age of death than we do--sushi sounds healthy to me.
Eating sushi or other meats uncooked is no more unsafe--assuming its handled right--than a rare steak. Rare hamburgers on the other-hand...NOT a good idea.
If the beef used for hamburg patties is ground at a local butcher or at least not at the meatpacking facility, the risk of e-coli is largely eliminated. Most e-coli outbreaks can be traced to patties made at meatpacking facilities where prior to preparation the beef came in contact with material from the intestines of the slaugtered animals.