Well, that's because... "systematic extermination or the usual prisonner camp disease ?" That's a negationnist talking point arguing that systematic extermination didnt happen and that the deaths (much fewer than the official numbers) in the camps was due to typhus. Typhus that is passed on by fleas and Zyklon B is an anti pests and was not used to gas jews but tho clean barracks of typhus bearing fleas. etc