There are 3 new world diseases I can think of, pinta, bejel, and yaws (also syphilis derivatives), which are all spread by skin to skin contact and probably wouldn't have much trouble spreading in Europe. The issue is that none of the three disorders are fatal. They could possibly lead to opportunistic infections, pinta, bejel, and yaws all cause huge skin damage, and there are a lot of opportunistic pathogens hanging around Europe. Alternatively, you could use a POD in which one of the three diseases mutates to a more fatal form. Fortunately, all three diseases are caused by bacteria, which can take up DNA from the environment, so it wouldn't be too hard to create a POD in which one of the three bacteria takes up DNA from something more deadly.
Alternatively, you could take a deadlier New World disorder and mutate it to spread more easily, but I actually don't know of any particularly deadly New World diseases, nor have I been able to find any on google yet. The deadliest New World disease I know of, syphilis (in the STD form) does not spread very quickly, requiring sexual contact, and is not very deadly either...