Here is a fairly recent and interesting documentary on allergies: http://www.cbc.ca/natureofthings/episodes/the-allergy-fix http://www.cbc.ca/natureofthings/ep

Here is a fairly recent and interesting documentary on allergies: http://www.cbc.ca/natureofthings/episodes/the-allergy-fix http://www.cbc.ca/natureofthings/episodes/the-allergy-fix Parasitic worms, and their modulation of the immune system (and the possible faulty human over-compensation for this) are one of a few different theories that are put forward. I thought I would link it here because it's fairly informative.