Scarlet fever is mainly on the rise in the UK. If it spreads to the US, it'll probably be from English visitors/migrants. So if they're speaking Spanish, Arabic or Hindi, you're cool - just avoid anybody speaking the Queen's English.
UK and East Asia. From November 2017...
https://www-m.cnn.com/2017/11/27/health/scarlet-fever-mystery-study/index.html
“Scarlet fever is mainly on the rise in the UK.”........
There are a lot of “migrants” entering the UK every day. What could go wrong?