Milnods
Technically, it’s known as mutated pseudocowpox, but that’s a mouthful. So was ‘milker’s nodule,’ but that at least could be trimmed down into a two-syllable word that sounded vaguely medical. Slang’s a funny thing. This version is contagious, from either skin contact or fluid exchange.
Anyway, milnods are what can happen when cowpox jumps species to a DNA-based bovine-equivalent, then jumps again into a DNA-based sapient alien species. Yeah, there’s a lot of those out there. Panspermia, Precursors, ancient alien species that used the same particular form of food yeast on all their planets; take your pick. The point is that people all over the Galaxy absolutely have to worry about catching each other’s germs.