Earlier quoted context omitted.
My mom developed an allergy to eggs after a blood transfusion. She long regretted never being able to eat another chocolate eclair.
That’s nuts. Seems like researchers should look really closely at weird side effects of blood transfusions since these are effectively “natural experiments” that would be impossible or unethical to run normally.
(Seems wikipedia removed this factoid now... and other sources state "most" snake venom)
I assume they tested on animals, not humans.