Tuesday, May 30, 2006

Chronic Allergies

by Joseph Chang (Class of '06)

Currently, over 50 million Americans suffer from allergic diseases. In fact, 54.6 percent of US citizens test positive to one or more allergens, such as dust mites, rye, ragweed, and cockroach, according to a recent national survey. Allergies are already the sixth largest source of chronic disease for Americans and cost the US health care system about $18 billion annually. In addition, the rate of increase of allergy sufferers is about 5 percent per year; specifically, the number of Americans who suffer from asthma has increased over 100% from 20 years ago to about 20 million, today.

Allergies occur when the body’s immune system reacts to the presence of an innocuous substance, such as pollen or dander, as if it were a dangerous pathogen, such as a virus or bacterium. The development of an allergy begins when the body is exposed to a protein in a harmless molecule and recognizes it as a possible danger. On the first exposure, the body produces specific antibodies called immunoglobulin E (IgE) antibodies which recognize the protein. These IgE antibodies then attach to mast cells, which are responsible for creating various chemicals, such as histamine, prostaglandins and leukotrienes, which jolt the body into anti-pathogen maneuvers, including inflammation and mucus production. The first time the body is exposed to these allergens, there will likely be no symptoms; however, the second time the body comes in contact with the allergens, the IgE molecules recognize the offending proteins and trigger the release of the mast cells’ chemicals and cause the typical stuffed nose and headache allergy-symptoms.

One of the major causes of allergies, as with many other ailments, is based on genetics. Studies show that children with one asthmatic parent have greater chances have having asthma than children with no asthmatic parents. Children with two asthmatic parents have even greater chances of having asthma. In addition, pairs of identical twins, who share the same DNA, have asthma more frequently than pairs of fraternal twins, who do not share the same exact DNA. However, genetics alone does not explain the dramatic increase in allergy rates over the past few decades.

A second cause of allergies is the diet. The reduced fresh fruit and vegetable intake and the corresponding low level of antioxidants and minerals in the American diet both increase the risk of getting allergies. In addition, antibiotic use may be helping the rise of allergies by killing of certain bacteria in the intestine which suppress allergy.

Additionally, the environment plays an enormous role in whether or not Americans develop allergies. Environmental pollution, especially airborne pollution, is often cited as sources of allergies. One example of the pollution on allergies is a study which showed that children who live near major highways and are exposed to diesel fumes exhibit increased sensitivity to allergens that they already react to. Another environmental factor that is being considered as a source of allergies is excessive cleanliness. Essentially, this idea of excessive cleanliness causing allergies, called the hygiene hypothesis, states that immune systems must be exposed to certain levels of pathogens when they are young. If developing immune systems do not come in contact with enough pathogens they will be unable to distinguish between harmless substances and true dangers to the body.


“Allergy Statistics.” National Institute of Allergy and Infectious Diseases. http://www.niaid.nih.gov/factsheets/allergystat.htm. May 30, 2006.

Newman, Judith. “Misery for All Seasons; Allergies: A Modern Epidemic.” National Geographic. May 2006.

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