Allergies

Allergies

It's hard to believe that items as unrelated as shellfish, pollen, animals, bee venom, peanuts and mold can all potentially lead to the same type of problem. What these substances have in common is that they are common allergens-they cause allergic reactions in some people.

With so many substances potentially causing so many problems, it's no wonder allergic diseases are among the major causes of illness and disability in the U.S., and the sixth leading cause of chronic disease in the U.S. Allergies affect as many as 60 million Americans, or one in every five adults and children, and are as common in women as in men. Thirty-five million people suffer from upper respiratory symptoms that are allergic reactions to airborne pollen; up to 10 million Americans are allergic to cats; and two million develop severe allergic reactions to insect stings. Food allergies are less common; and while about one out of three people say they have a food allergy, only about three percent to eight percent of children younger than three years old, and one percent of adults have true allergic reactions to foods. Unfortunately, about 200 deaths per year are attributed to food allergies.

An allergy is a reaction of a person's immune system to a normally harmless substance, one that doesn't cause problems for most people. In the allergic woman, the offending substance causes the immune system-which functions as the body's defense against invading agents such as bacteria and viruses-to respond to a "false alarm." Her immune system treats the allergen as an invader by generating large amounts of a type of antibody-a disease-fighting protein known as IgE-that attaches to the body's tissue and blood cells. The cells are then triggered to release powerful inflammatory chemicals like histamine, cytokines and leukotrienes. These chemicals act on tissues in various parts of the body, such as the respiratory system, and cause the symptoms of the allergy.

Allergies can be more than just bothersome. While some allergies cause symptoms of rhinitis like sneezing, runny nose and watery eyes; skin irritations like itching and hives or eczema; or gastrointestinal distress; in some people, the allergic response can lead to anaphylaxis or anaphylactic shock-a sudden and sometimes deadly drop in blood pressure. Anaphylactic shock can potentially stop the heart or lead to complete closure of air passages, causing death by suffocation.

Allergies that result in respiratory symptoms can be caused by pollens, molds and fungi, dust or dust mites, animals, medications, foods, latex and other substances. Food allergies, which can cause a wide variety of symptoms, are most commonly caused by shellfish and other fish, peanuts and other nuts, wheat, soy, dairy and eggs. Contact allergies, or allergic reactions caused by a person's skin coming in contact with a substance, are most usually caused by, nickel, polishes, rugs, fabric softeners, deodorants, cosmetics, perfumes, preservatives, dyes, and foam insulation. And don't forget plants like poison ivy, poison oak and sumac. There is a compound in these plants that can cause severe skin reactions in people who are allergic-up to 85 percent of Americans.

Allergies have a genetic component. If one parent has allergies, chances are one in three that each child will have an allergy. If both parents have allergies, it is much more likely (seven in 10) that their children will have allergies. Adults usually do not lose their allergies, but children can sometimes outgrow them. In addition, while people are born with a genetic predisposition to allergies, sometimes they don't develop them until well into adulthood. Exactly what turns these genes on and when remains a bit of a mystery. Some researchers speculate that the more you are exposed to a potential allergen, the more antibodies to that allergen you can build up, until finally one day, they are released in an allergic reaction. Once you become "sensitized," you're going to get recurring symptoms every time you are exposed to the allergen.