Allergies

ALLERGY AND HYPERSENSITIVITY

Most people use the word "allergy" to describe all types of hypersensitivity. In this chapter, the most common forms of true aller­gy are described. A specific antibody — called IgE — is associated with these conditions. The IgE antibody is found in high levels in allergic people. It reacts with symptom-causing allergens such as pollen, mold spores, animal dander, dust mites, and certain types of food or medications.

Allergies can be triggered or worsened even by non-allergic factors such as infections or air-borne irritants. Plus, allergies give dif­ferent symptoms to different children, and can range from mild to life-threatening. Therefore, allergies are difficult to classify, and preven­tion and treatment vary from child to child.

THE FETUS AND ALLERGY

IgE antibodies are formed in the third or fourth month of pregnanc^y. Nine out of 10 children with a high IgE count at birth later develop allergies. However, three-quarters of people with allergies had a normal IgE count at birth. Diets that avoid potential allergens such as eggs or cow's milk during pregnancy do not protect the unborn child from allergies. Therefore, you should eat normally (but well) when pregnant. On the other hand, smoking does appear to increase the risk of developing an allergy later on.

THE INFANT AND ALLERGY

Some newborns produce IgE antibodies soon after birth. These are primarily to pro­teins in foods such as eggs and cow's milk. Even the tiny amounts of such proteins present in breast milk are enough to trigger the process. Non-allergic children produce small amounts of IgE antibodies without having an allergic response. Some allergic

children, however, produce high levels of IgE antibodies and develop allergic symp­toms. Allergy to foods such as eggs, milk, and wheat may decline during toddler age, whereas allergy to fish, peas, peanuts, and shellfish lasts longer perhaps through­out life.

ALLERGIC  ILLNESSES  DURING  THE  FIRST  YEAR

Atopic eczema is common in the first year. The child first develops dry, rough, slightly itchy skin. This is followed by a rash that appears first on the face, then gradually spreads over large areas of the body. The rash may ooze and be crusty. It later moves to the back of the knees and inside the elbows. Much of the eczema during the first 12 months is related to food allergies, most commonly to eggs and cow's milk. Food allergies can also give other symptoms, such as vomiting, flushed skin, itchiness, hives, or allergic swelling (particularly around the mouth and eyes). Other, less common symp­toms are diarrhea, difficulty breathing, or slow growth.

Allergic children may also have a sensitive digestive system, with tendency to colic, vomiting, frequent loose stools, and slow weight gain. Such children often have hypersensitive skin, respiratory system, and intestines before they develop an allergic ill­ness. Fortunately, many hypersensitive chil­dren don't become allergic later on. Real food allergies are uncommon, but the risk of developing diet-related allergies is greater with infants than with toddlers. The intesti­nal system isn't fully developed in very young children, which can cause problems if the child receives sensitizing proteins (such as eggs or cow's milk) too early.

INHERITANCE AND ENVIRONMENT

The likelihood of developing allergies is about 6 in 10 if both parents are allergic, and 3 in 10 if only one parent is allergic. If neither parents has allergies, there is still a 1 in 10 chance that the child will develop some form of allergy. It's now accepted that we only inherit the tendency for allergy — not a par­ticular allergic illness. Factors in the environment can be divided into two groups. The first group consists of

true allergens such as eggs, fish and seafood, dairy products, various grasses and tree pol­lens, dust, mold and fungal spores, feathers, and animal dander. These true allergens pro­duce an 1gE-type reaction and symptoms appear upon exposure. Other environmental factors that activate or aggravate allergic reac­tions can be considered a second group. These factors include air pollution, unhealthy indoor climate (including smoking), changes in diet, and so forth. This may explain why allergic diseases have increased so dramati­cally over the last decade or so.

BREAST-FEEDING AND ALLERGY