Do you think they have vacuum cleaners in The Known World? I mean there are can tanks and other machines but maybe vacuums wouldn't be seen as necessary. But then, if the disease can be spread by vermin beasts and the like, maybe having was to clean stuff like that would help to stop outbreaks.
Vacuums were invented in the 1860s, but remained a luxury item 'til about WWII. Even quite a while after that, they had issues combining power
and maneuverability so as to truly
get at the dusty places, and would not have been suitable to clean out anything heavier and stickier than dust.
Depending on where you need to clean up and how infectious the Rash is, using a post-Rash-grade vacuum might even be a non-starter. A vacuum having a filter that keeps it from just spreading microscopic allergens around (much smaller than the particles of common dust) is still not a standard feature even today.
(Fun fact: If you should ever have a chili powder spill, do
not try to use a run-of-the-mill vacuum to clean it up unless it's pretty tame stuff or you can afford turning the room into an off-limits zone for a day or two.)
