EDITORIAL BACKGROUND

ALLERGY

An allergy develops when the body’s immune system becomes sensitized and overreacts to a foreign substance that ordinarily is harmless. An allergic reaction can occur whenever the allergy-causing substance – called an allergen – is inhaled, swallowed or absorbed on contact with the skin.

When an allergen enters the blood stream, it stimulates the production of an allergic antibody called immunoglobulin E (IgE). When IgE reacts with an allergen, it triggers the production of histamine and other chemicals that cause blood vessels to widen, smooth muscles to contract and affected skin areas to become red, itchy and swollen. The inflammation and irritation produced by these chemicals can affect many parts of the body – the nose, eyes, lungs, skin or digestive system. Sometimes sensitivity does not occur on first contact with the allergen, but may develop after repeated exposures.

Prevalence of Allergies
According to the National Institute of Allergy and Infectious Diseases, as many as 50 million people in the United States suffer from various types of allergies. Of these, 20.3 million have asthma, a chronic lung disease often triggered by allergies. A first allergy attack is most likely to occur in childhood or even in infancy, but allergies can develop at any age.

Causes of Allergy
In most cases allergies are inherited. Children whose mother and father both have allergies have a 75 percent chance of being allergic; children with one allergic parent, or relatives on one side of the family with allergies, have a 50 percent chance of developing an allergy. Allergies also may be triggered by excessive exposure to a food or other substance. For example, there is a high incidence of fish allergy among Scandinavians and of rice allergy among the Japanese. Allergies also may develop in workers whose jobs bring them into repeated exposure to certain chemicals or substances – such as health care workers who become sensitized to the latex in rubber gloves.

If an individual has the tendency to be allergic, there are many substances that may trigger an allergic reaction. Among the most common allergens are pollens, molds, house dust mites, animal danders, feathers, natural rubber latex, chemicals used in industry, foods, medicines and insect stings.
In some cases, emotions such as anxiety, fear, anger or strong excitement may precipitate or aggravate an allergic reaction, but the physical basis for allergy is very real and allergies are not “all in the head.”

Types of Allergies
Allergic diseases, or reactions, may involve any part or system of the body. Frequently, the respiratory system is involved, resulting in allergic rhinitis (e.g., hay fever) or asthma. When the skin is involved, the individual may develop a rash (dermatitis or eczema) or hives (urticaria).

Allergic Rhinitis
Rhinitis is a general term that describes a variety of nasal allergies with symptoms in the upper respiratory system, including nasal congestion, sneezing and runny nose. Allergic rhinitis is extremely common, affecting 10 percent to 30 percent of the population, both adults and children. Often the condition is seasonal, such as hay fever, and is caused by tree pollens, grasses, weeds or molds. Despite its name, hay fever is not caused by hay (ragweed is a common culprit) and is not accompanied by fever. Depending on where the allergic individual lives and the time of year that pollination occurs, symptoms may be experienced in the spring, summer or early fall, and may last until frost. The sufferer has episodes of sneezing, itching and weepy eyes, runny nose, and a burning or itchy sensation in the throat or palate. Asthma is sometimes a complication.

In many cases, allergic rhinitis is a perennial problem, triggered by year-round allergens such as ordinary house dust mites, animal danders, molds or, less commonly, certain foods. Some people may experience both seasonal and perennial rhinitis, with perennial symptoms worsening during specific pollen seasons.

Allergic rhinitis is often mistaken for infectious rhinitis – common cold – or for sinus infections. People with chronic nasal or respiratory symptoms should be evaluated by an allergist-immunologist to determine if an allergy may be the culprit.

Irritant Rhinitis
Many people have recurrent or chronic symptoms similar to those of allergic rhinitis, but the disorder is not caused by allergy. This condition is called irritant rhinitis, or “vasomotor rhinitis.”

Irritants that can trigger vasomotor rhinitis include cigarette smoke, strong odors and fumes, including perfume, hair spray, other cosmetics, laundry detergents, cleaning solutions, pool chlorine, car exhaust and other air pollution. Other irritants are spices used in cooking, alcoholic beverages (particularly beer and wine), aspirin and certain blood pressure medications.

These agents are not allergens, do not induce formation of allergic antibodies and do not produce positive skin reactions.

Asthma
Asthma is inflammation and obstruction of airflow in the bronchial tubes. It is characterized by coughing, wheezing and difficulty in breathing. It is frequently, but not always, associated with a family history of allergies. Any of the common allergens may prompt an asthma attack; infections in the sinuses or bronchial tubes also may contribute to the problem. People with asthma also are affected adversely by factors such as air pollutants and cigarette smoke. Sometimes stress and other emotional factors play a role.

Asthma can begin at any age and, if neglected, tends to recur. An estimated 4,500 people die of complications related to asthma each year in the United States.

Food Allergies
Approximately 1 percent to 2 percent of adults and as many as 2 percent to 4 percent of children suffer from food allergies. Many parts of the body may be affected, and the frequency and severity of symptoms can range from mild to life-threatening. Among the symptoms of food allergy are vomiting, nausea, stomach cramps, indigestion, diarrhea, hives, skin rash, headaches, asthma, earaches and rhinitis. In rare cases, food allergies cause anaphylaxis – a severe, system-wide allergic reaction that is potentially fatal.

Almost any food can cause an allergic reaction, but the most common allergy-causing foods are eggs, milk, nuts, soy, seafood, fish, corn and wheat. Individuals who are allergic to a particular food may also be allergic to related foods. For example, a person allergic to peanuts often cannot tolerate other members of the legume family of foods, such as peas, beans and licorice.

Allergic Dermatitis
Also called eczema, allergic dermatitis is a non-contagious, itchy rash that is frequently triggered or aggravated by allergies. It is often seen in the creases of the arms, legs and neck, although it may cover the entire body. Allergy to certain foods is often the cause. Hand dermatitis in health care workers may be symptom of latex allergy, a potentially life-threatening allergy to the natural rubber latex that is found in some rubber gloves. Contact dermatitis is a rash that results from direct skin contact with an allergen, such as an animal, plant, chemical or mineral. Poison ivy is the most common cause.

Hives (Urticaria)
Hives are itchy welts of varying size that may appear on the skin of the body or face, on the lips, tongue, eyes or ears. In severe cases, they may develop in the throat or elsewhere inside the body. When the swellings are large and invade tissues below the skin’s surface, they are called “angioedema.”  Allergy to food or drugs, especially penicillin and aspirin, are well-known causes. Hives also may result from an underlying disease or in response to emotional stress. Sometimes the exact cause cannot be determined.

Anaphylaxis
In rare instances, allergies can trigger a potentially fatal allergic reaction called anaphylaxis in which many parts of the body are affected at once. The trigger may be an insect sting, a food such as nuts or shellfish, medications or certain substances such as natural rubber latex. Symptoms, which usually are immediate and progress rapidly, may include a dangerous drop in blood pressure,
flushing, difficulty breathing, swelling of the tongue, throat and nose or loss of consciousness. Emergency medical attention should be sought at the first sign of an anaphylactic reaction.

Allergies in Children
Allergic disorders are the number one cause of chronic disease in children. Any child may acquire an allergy, but it is most likely to occur in children from families with a history of allergy. Foods are a common cause of allergy in infancy.

Parents should observe children for allergic tendencies. Symptoms may include chronic nasal congestion, wheezing or coughing, ear congestion or gastrointestinal upset. Irritability or other changes in behavior are sometimes the result of allergy.

When to See an Allergist-Immunologist
Individuals should see an allergist-immunologist if:
• Allergies are causing secondary symptoms such as chronic sinus infections, nasal congestion or difficulty breathing.
• Hay fever or other allergy symptoms persist for several months of the year.
• Antihistamines and other over-the-counter medications do not control allergy symptoms, or create unacceptable side effects, such as drowsiness.
• Asthma or allergies are interfering with day-to-day activities or quality of life.
• Warning signs of asthma are experienced. These include a wheeze or cough, especially at night or during exercise, shortness of breath or a tight feeling in the chest.

An allergist-immunologist is a physician who specializes in the diagnosis and treatment of allergies and asthma. After earning a medical degree, the allergist completes a three-year residency training program in a field such as internal medicine or pediatrics, followed by a two- or three-year program of study in the field of allergy and immunology. The allergist has passed a qualifying examination and is specially trained to identify the factors that trigger allergies or asthma and help the patient prevent or treat the condition.

Diagnosing Allergies
Allergy diagnosis requires skill, planning and close cooperation between the patient and his or her allergist-immunologist. The allergist usually begins by taking a detailed history. Information about the patient’s work and home environment, eating habits and family medical history often provides clues that can help pinpoint the problem.

A physical examination and laboratory tests also may be performed. The most common allergy test is an allergy skin test, which introduces small amounts of the suspected allergen into the skin. A positive reaction – a welt, swelling or inflammation on the skin – indicates the presence of allergic antibodies.

Sometimes blood samples are taken to detect the extent of antibody production against an allergen. If a food allergy is suspected, the patient may be asked to keep a daily food diary listing all food and medication ingested or to follow a special diet.

Treating Allergies
Once an allergy has been diagnosed, there are a number of treatment options. The allergist works with the patient to determine the best treatment approach, depending on the frequency, duration and severity of the individual’s allergy symptoms. Among the options for treating allergy are strategies to avoid or reduce the individual’s exposure to allergens, medications to control allergy symptoms, or immunotherapy (allergy shots) to build the body’s resistance to allergens.

Avoidance
The best treatment for allergy is to avoid the allergen that triggers an attack. This is relatively easy if the problem is feather pillows or dust-catching furniture or a certain food that can be removed from the diet. Allergens such as plant pollen and molds, however, are difficult to escape. For example, ragweed – which affects 75 percent of allergic rhinitis sufferers – is found throughout the United States. Pet owners who are allergic to animal dander may be reluctant to give up a favorite pet. Even moving to a new climate doesn’t always solve the problem, and allergists seldom recommend so drastic a measure. Although some people find relief in regions of the country where a particular allergen is not present, others find they escape one allergy-causing substance only to develop sensitivity to another.

When it is not possible to avoid the substances that trigger allergy symptoms, there are steps that can be taken to decrease exposure. Air conditioners or electronic air filters may help prevent outside allergens from finding their way inside. Outdoor activities can be restricted when pollen counts are high. Wearing a face mask outdoors during pollination seasons also may be helpful. A healthy lifestyle, including a well-balanced diet, regular exercise, proper rest and avoidance of stress and general pollutants such as cigarette smoke is an important measure that will not cure an allergy but will contribute to better resistance.

Medications
When allergens cannot be avoided, there are many medications available today that often can control the symptoms of allergy. Medications come in many forms, including tablets, nasal sprays, eye drops, creams and liquids. Decongestants and antihistamines, which help to reduce nasal congestion, runny nose, sneezing and itching, are the most commonly used allergy medications. Other medications, such as cromolyn, work by inhibiting the release of the chemicals that cause allergic reactions. For severe cases, corticosteroids may be prescribed to counteract inflammation.

The proper choice of medications, and the timing and dosage for taking allergy medications, are important to successful control. The allergist-immunologist works with the patient to determine the appropriate medications and dosage. If symptoms persist despite the proper use of medications and the removal of allergens from the environment, immunizing injections may be used to control the disease.

Immunotherapy
Allergen immunotherapy, known as “allergy shots,” may be recommended when patients don’t respond well to treatment with medications, experience side-effects from medications or are subjected to frequent exposure to an allergen.
In immunotherapy, injections of a diluted allergy extract are given at variable intervals over a period of three to five years. The therapy helps the body build resistance to the effects of the allergen and can reduce the intensity of allergy symptoms.

Living with Allergies
The tendency to allergy is often an inherited, life-long condition that cannot be cured, but this does not mean that a person has to “live with” the unpleasant symptoms of allergies. In the great majority of cases, the allergist-immunologist can work with patients to develop a strategy to control allergies so that individuals remain symptom-free and are able to lead normal lives.

For More Information
No matter what the cause of allergy misery, the American College of Asthma, Allergy and Immunology (ACAAI) can help consumers bring their allergies under control. For more information about allergies or asthma, call the College at 1-800-842-7777 or visit its Web site at www.acaai.org. The ACAAI is a professional medical organization comprising more than 4,950 allergists-immunologists and related health professionals dedicated to the clinical practice of allergy, asthma and immunology through education and research to promote the highest quality patient care.