I am not sure that there is an increase. I found “this article”: very interesting. Here is an excerpt (emphasis mine):
“But the medical research suggests that severe peanut allergies are not as common as people think and are surprisingly difficult to diagnose accurately. And although, as a parent, it may seem that peanut allergies have reached epidemic proportions, the evidence is surprisingly thin.
True allergies result when the immune system mistakes innocent substances—like dust, pet dander, and food proteins—for harmful invaders. Almost a century ago, the scientist Carl Prausnitz injected his skin with blood from a colleague allergic to fish and got hives at the injection sites upon eating fish. Later, scientists realized that blood from allergy sufferers contains an antibody called IgE, which erroneously attracts friendly fire from the immune system and can cause runny noses, red eyes, wheezing, hives, and, rarely, shock and death.
According to Anne Munoz-Furlong, a researcher and the founder of the Food Allergy and Anaphylaxis Network, an advocacy group, today about 25 percent of parents believe that their children have food allergies, although only about 4 percent really do. A parent may suspect one after a few spit-ups or a screaming fit following a new food. Yet these are rarely true allergies. And even among children with true allergies caused by harmful IgE, only a tiny fraction will have life-threatening reactions, called anaphylaxis.”
I also have what is a somewhat unpopular belief that it is up to the allergic child and its parent to avoid peanut dangers. The public, in my opinion, should not have to eschew peanuts and peanut butter simply because some people have a rare reaction to it.