new shellfish allergy

Hello there, my sister has shellfish allergy yet again. What can you tell me about this condition? Thank you in advance for everything you say. It will mean much for me. I know that this type of allergy is abnormal body response for something in shellfish. But what exactly? Any thoughts?

It is abnormal body response to protein found in shellfish. That is the complete answer. She will have to avoid some food. Everything that contains: abalone, crab, lobster and scampi should be avoided. There are more things that should be avoided, such as: mussels, oyster, mollusks, shrimp and periwinkle. I think that there are more things but I am not sure. Be sure to advise a doctor about this.