There are no exact figures for those that suffer from allergies, as many do not consult physicians; they just medicate themselves or cope with the discomfort. However, one or more allergies are thought to affect 15 to 20 percent of North Americans. According to the U.S. National Institutes of Health (NIH), one in five Americans has an allergy-related illness during his or her lifetime.
Statistics from the Canadian Society of Allergy and Clinical Immunology show that about one in six Canadians is treated each year for an allergic disorder, including seasonal hay fever, asthma, eczema, hives, and cat, food, insect and drug allergies. One in five North American children sees a physician because of an allergy, and some children are hospitalized for it.
The Main Reason Why Children Are Hospitalized For Allergies
- An estimated 15 to 20 percent of North Americans suffer from hay fever along with nasal symptoms triggered by pollens, dust, animal dander (a mixture of dried saliva and skin flakes) and other airborne particles.
- About 1 to 3 percent of infants are allergic to cow’s milk proteins.
- About one in 600 allergy-prone people is at risk of severe anaphylaxis (a life-threatening reaction).
- About 5 to 10 percent of the North American population have asthma, with one in seven children affected, and over half the asthma cases are allergy-related. The incidence of asthma has increased by 33 percent during the past decade, with deaths doubled since the 1980s — especially among children.
- Some 1 to 2 percent of North Americans have food allergies.
- Generally, allergy-prone people — for example, those who suffer from hay fever or dust allergy — are not more vulnerable to insect stings, or drug or food allergies. However, people with asthma who also have allergies are at above average risk of severe reactions.
- About 3 percent of the adult North American population have an insect-venom allergy, with an estimated 25 to 50 insect-sting deaths annually.
- About 1 to 3 percent of North Americans have a drug allergy, and 5 percent of these may be allergic to more than one medication. Penicillin and its relatives are the medications chiefly responsible for severe drug allergies; almost 10 percent of penicillin-treated patients are at some risk.
Allergies and the Immune System
An allergic reaction is an overreaction of the body’s immune system. The immune system is part of the defense mechanisms that protect the body against harmful foreign (“non-self”) substances that enter or threaten it.
The immune system signals white blood cells to rush to the “attack site” and engulf the invading particles, and also produces antibodies that inactivate or destroy specific invaders.
Unlike a normal immune reaction, which is launched against dangerous bacteria, viruses or parasites, an allergic reaction is a misguided attack against inoffensive proteins such as those in cat dander, pollens, dust mites or food.
Although it has been known since the early 1900s that allergies are due to immune-system activity, only in the late 1960s did researchers finally identify the specific “allergy antibody” — immunoglobulin E, or IgE for short — responsible for some allergic reactions.
Today we know that although IgE antibodies are involved in some types of allergy, others may be caused by different immune-system components.
As the biochemical processes involved in the allergic response are unraveled, scientists understand better how to develop drugs and therapies against them. Besides antihistamines, which block the action of histamine, newer medications are being designed to block other mediators and other steps in the allergic reaction.