Use of "measles" as an interjection
I have a friend from Illinois USA who uses measles as an exclamation of frustration or disappointment. For example,
Measles! My flight was just canceled.
I find this odd. Is it commonly used this way?
To address your question, I must say that I have never heard of "measles!" used as an interjection before, and that googling confirms its rarity (by not turning up any pertinent results). So it's not common. It may just be a quirk of your friend; I know of someone who says "sugar pie!" when something goes wrong.
In my opinion, anything can be used as interjection, as long as it is used to express strong emotions.