Yellow fever - I do not know about at all. However, if you visit South America or Africa, you need a shot to be able to visit other countries afterwards. This is why those two continents are last on my list. You do not need to fear this illness if you do not plan travel to either of those places.
Anything mosquito borne is suspect as the big guys are messing with the bugs these days. They just released a bunch in Northern California so expect outbreaks of something! Fear porn coming your way.