Typhus was spread by lice. This is a disease which caused loss of appetite. Combine that with Allied bombing of supply lines, and the result was emaciated corpses. First of all, you should be aware there's no such thing as "open air gassings". Yet the corpses "stacked up like cordwood" were outside, in the open as exampled by this British soldier. Such as these at Buchenwald, and German women being forced to handle corpses because the Soviets knew the bodies were diseased. Allied soldiers had a stockpile of outdoors, unincinerated corpses.