I'm more surprised that there have been no malaria cases in the US in 20 years. It isn't exactly a disease like Ebola or Polio that's on the brink of extinction. Hundreds of millions suffer from it worldwide every year.
There've been cases, they just haven't gotten it here, because the local mosquito populations aren't biting infected people given its rarity. Sounds like that's changing. Goodie.
Yeah, this is the first of probably a few diseases that will be coming back to, among others, the US as global temperatures rise.