Yeah, they have come up with higher numbers and they were indeed deaths, not all casualties (deaths are only part of casualties).
Still, it’s always informative to know up to that time or later, about half of deaths would be due to disease and injury (leading to disease or bleed-out, etc).
Today we would call that dying from exposure. And it was at least half, if not more. I have read about the sound of the coughing in the camps when they were awakened by bugle.