Peanut allergies are the body's overreaction to certain proteins found in peanuts. The immune system's response to these allergens is to trigger an antibody, which then triggers other chemicals. One of the scariest results of these chemicals is the chance for anaphylaxis, which is a potentially fatal condition in which sufferers have trouble breathing because of constricted airways, experience a sudden and drastic drop in blood pressure, have an increased pulse rate, and sometimes even pass out.
Estimates say that in the United States, thousands of people visit the emergency room annually because of allergic reactions to food. Somewhere around 150 to 200 people die in the U.S. each year because of food allergies. It's estimated that around 50 percent to 62 percent of those fatal cases of anaphylaxis were caused by peanut allergies. Meanwhile, around 10 people in the United Kingdom die each year because of food allergies. However, these figures are not completely reliable, in part because allergic deaths aren't considered reportable events.
Although the number of people who die annually from peanut allergies is in the low hundreds at most, peanuts have gotten a reputation for being particularly deadly. While some people call peanut allergies an epidemic, others say the situation has been blown out of proportion. For example, Professor Nicolas Christakis of Harvard Medical School told the BBC that there was "a gross overreaction to the magnitude of the threat." He even said that the fear of peanuts had led to a situation resembling mass psychogenic illness -- once known as epidemic hysteria. Meanwhile, the "Journal of Allergy and Clinical Immunology" notes that the "epidemic" of peanut allergies only applies to the U.S. In France, the rate of peanut allergy is somewhere between .3 percent and .75 percent; Denmark is lower at .2 to .4 percent; and in Israel the rate of peanut allergy is around .04 percent.