Sentence:  Let us assume that it would be possible for an enemy to create an aerosol of the causative agent of <WSD>epidemic</WSD> typhus ( Rickettsia prowazwki ) over City A and that a large number of cases of typhus fever resulted therefrom . 
Meaning of the word marked with <WSD> tags:  (especially of medicine) of disease or anything resembling a disease; attacking or affecting many individuals in a community or a population simultaneously