I wonder the same thing. I’m 66 and don’t ever recall hearing abou this until maybe 20 years ago. Of course, the internet took off 20 years ago and now we get highly local stories like this all the time. Has it always been with us? Is it something new? What changed?
There’s this infamous peanut story.......the young girl was an athlete.....with a peanut allergy.
She had a bowl of the famous chili at a restaurant....no one associates chili with peanuts.
However the chef had a secret ingredient....peanut butter to thicken the chili.
The girl did get all the symptoms but b/c she had not eaten peanuts, she ignored them......and died.
If I had to guess, I'd say it's some kind of vaccination, with a component of the vaccine contributing to an immune response leading to the allergy.