Diseases & Conditions


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Allergies


Overreactions of the immune system toward substances that are typically harmless to most people. In someone with an allergy, the body’s immune system treats the substance (called an allergen) as an invader and reacts inappropri-ately—triggering the symptoms seen in allergies. Everything from dust to cats to peanuts to cockroaches can cause allergies in children. Up to two million children have some type of allergy. It has been estimated that children miss more than two million school days per year because of allergies. In the most common type of allergy, at the first exposure to an allergen, the immune system releases histamine and other chemicals to defend against the allergen “invader.” It is the release of these chemicals that causes allergic reactions, as the body attempts to rid itself of the invading allergen. Some of the most common allergies include those to food and to airborne allergens such as pollen, mold, dust mites, and animal fur or dander. Allergies can be seasonal, like pollen or certain molds, or year-round, like dust mites. Regional differences also occur since different allergens are more prevalent in different parts of the country or the world. For example, peanut allergy is unknown in Scandinavia, where peanuts are not eaten, but common in the United States, where the per capita consumption of peanuts is about eight pounds a year. Children inherit allergic tendencies from their parents; if one parent has allergies, there is a one in four chance that a child will also have allergies. The risk increases if both parents have allergies. Allergies also tend to develop in response to multiple substances. If children are allergic to one substance, it is likely that they will be allergic to others. Some children suffer from cross-reactions, so that a child who is allergic to birch pollen might have reactions when eating an apple because the apple contains protein similar to the pollen. Children who are allergic to latex are also more likely to be allergic to kiwi fruit or bananas. The type and severity of allergy symptoms vary from child to child. Airborne allergens can cause ALLERGIC RHINITIS (sneezing, itchy nose or throat, nasal congestion, and coughing). These symptoms are often accompanied by “allergic conjunctivitis”— itchy, watery, red eyes, and dark circles around the reddened eyes. Allergic rhinitis occurs in about 15 percent to 20 percent of Americans and typically develops by age 10, reaching its peak in the early 20s. The symptoms of allergic rhinitis and conjunctivitis can be mild or severe and may occur only at certain times of the year or all year round. If symptoms occur with wheezing and shortness of breath, the allergy may have progressed to asthma, which can be a serious condition. Food Allergies Food allergies may cause only an itchy mouth and throat; other allergies trigger a rash or cramping, with nausea and vomiting or diarrhea, as the body attempts to flush out the irritant. Still other common allergic food symptoms include hives, and in more severe cases, shortness of breath. In severe reactions (such as in tree nut or peanut allergies), the child may develop a sudden, life-threatening reaction called anaphylactic shock. Severity of food allergies and when they develop depends on the quantity of the food eaten, the amount of exposure the child has had, and the child’s sensitivity to the food. Common foods that may cause allergies include cow’s milk, soy, egg, wheat, seafood, nuts, and peanuts. Severe symptoms or reactions to any allergen require immediate medical attention. Children with a severe allergy to foods must carry injectable epinephrine (Epipen), which can reverse anaphylactic shock. Fortunately, severe or lifethreatening allergies occur only in a small group of children. There is no cure for allergies, but it is possible to treat the symptoms. The easiest way is to eliminate exposure to allergens. If that is not possible, then medications may be given, such as ANTIHISTAMINES or a nasal spray steroid. In some cases, an allergist may recommend allergy shots to help desensitize a child. If a child is extremely sensitive to a particular food, or if the child has asthma in addition to the food allergy, his doctor will probably recommend that parents carry injectable epinephrine (Epipen) to counteract the allergic reaction in the event of an inadvertent exposure. Food allergies are usually not lifelong, but reactions to nuts or seafood can last a lifetime. In these cases, avoiding the food is the only way to avoid symptoms while the sensitivity persists. Airborne Allergens Those who react to airborne allergens usually have allergic rhinitis and allergic conjunctivitis. Airborne allergens include dust mites, cockroach parts, pollens, and molds: • Dust mites These microscopic creatures are one of the most common causes of allergies and are present year-round in most parts of the country, although they do not live at high altitudes. Dust mites live in bedding, upholstery, and carpets. • Cockroaches The body parts and waste products of these insects are also a major household allergen, especially in inner cities. Asthma rates of inner city children are high, probably due to cockroach exposure in overcrowded buildings. • Pollen Trees, weeds, and grasses release these tiny particles into the air to fertilize other plants. Most people know pollen allergy as hay fever or rose fever. Pollen allergies are seasonal, and the type of pollen a child is allergic to determines when he will be symptomatic. For example, in the mid-Atlantic states, tree pollination begins in February and March, grass from May through June, and ragweed from August through October. Pollen counts measure how much pollen is in the air. Pollen counts are usually higher in the morning and on warm, dry, breezy days; they are lowest when it is chilly and wet. Although they are not exact, the local weather report’s pollen count can be helpful when planning outside activities. • Molds These fungi thrive in warm, moist environments. As with pollen, mold spores are released into the air to reproduce. Outdoors, molds may be found in poor drainage areas, such as in piles of rotting leaves or compost piles; indoors they thrive in dark, poorly ventilated places, such as bathrooms and closets. Mold buildup may be found in damp basements or basements with water leaks. A musty odor suggests mold growth. Although molds can be seasonal, many thrive year-round, especially those indoors. Animal Allergens All warm-blooded, furry animals can cause allergic reactions, usually the result of proteins in their saliva, dander, and urine. When the animal licks itself, the saliva gets on the fur. As the saliva dries, protein particles become airborne and work their way into fabrics in the home. Cats often cause the most problems because their salivary protein is extremely small, and they tend to lick themselves as part of grooming more than other animals. Allergy Skin Tests An allergist can determine the cause of an allergy by using skin tests for the most common environmental and food allergens. In the test, a drop of a purified liquid form of the allergen is placed on the skin, or injected just under the skin. After about 15 minutes, if a reddened swelling appears at the injection site, the test is positive. Skin tests are less expensive and more accurate than blood tests for allergies, but blood tests may be required in children with skin conditions or those who are extremely sensitive to a particular allergen. Blood tests can also help determine if a child has outgrown a food allergy.