Why Allergies?

    The topic of allergies is actually very interesting to me.  My roommate and my stepfather are constantly complaining about allergies, primarily caused by airborne particles, yet neither of them actually know what causes an allergy or why it happens.  Every time someone lights up a cigarette or gets too close with a furry animal they begin sneezing or sniffling.  What I was surprised to learn is that there is so much more to allergies.  Some allergens cause severe reactions and allergies are caused by all sorts of different things.  The article handed out in class (Beebe) is about Ragweed allergies.

What is an Allergy?

      Most everyone has heard someone at some point or another say "My allergies are acting up again." or "It's allergy season again." yet most people have no idea what an allergy really is.  In fact many people claim to have an allergy but have never been checked for one.  As it turns out only about 20% of the US population has allergies (Sompayrac).  Of course the first thoughts that come to mind may be of sniffling and sneezing due to pollen and pets or of more severe incidents like difficulty breathing, due to certain foods like shellfish and peanuts. 

    The question that must be answered first is what is an allergy?  An allergy is the result of a person's immune system making a mistake and identifying a fairly harmless substance as harmful.  The immune system will attack the substance with an overwhelming force, which causes the person to have symptoms as small as sniffling or as severe as respiratory or organ failure.

What is the Immune System?

    The immune system is made up of many barriers protecting each of us from invading cells such as bacteria and viruses.  These barriers include something as visible as the skin to things we may not be familiar with such as white blood cells.  A good example of how well your immune system works comes from this site by Marshall Brain.  The second paragraph on Brain's page explains that when a person dies it does not take much time for the body to decompose.  The immune system, when it is working, stops these decomposers from entering the body and destroying it.  If the immune system was not working it would be no time at all before the body would be decomposed.

    In a normal immune system T-Cells and B-Cells (also known as lymphocytes), which are two of many different cells that make up the white blood cells travel through the body checking every cell for invaders.  Once a potentially dangerous cell is found, the lymphocytes take a sample antigen ("any foreign substance of a biological nature") from the invader back to the lymph node (Clark).  The T-Cell must first recognize the antigen before the B-Cell can produce antibody against it (Burrell).  Then the B-Cell changes to a plasma cell and produces antibodies to fight off the invader.

    Antibodies are proteins produced in the body, and there are five types, which are IgA, IgD, IgE, IgG, and IgM (Ig= Immunoglobulin).  IgE, although produced by all people, is the cause of allergic reactions in people with allergies because it is produced in an excessive amount.

An Allergic Reaction

    When an allergic person comes into contact with their allergen for the first time the lymphocytes mistake the otherwise harmless cell as an invader.  The lymphocytes take a sample of the invaders antigen back to the lymph nodes and produces an overabundance of IgE, which connects to a mast cell or basophil.  Mast cells and basophils are "types of cells containing histamine and other allergy mediators instrumental in the allergic response" (Beach).  Then, the second time a person comes into contact with the allergen, the IgE cells connect to the allergen and the mast cell or basophil releases histamines and other chemicals in an excess amount.  This is what causes the sniffling, sneezing, itchiness and other allergy symptoms.

Specific Allergies

Food

    "Interestingly, 20% of all adults believe they have food allergies" (3)  However, Medical News Today states that only 1% to 2% of those studied actually have a food allergy, which coincides with the FDA's estimate that about 1.5% actually do have a food allergy.  The others are probably food intolerances.  If a person has a food allergy the allergen must be present and an increased amount of IgE and mast and basophil cells must be present.  Also, a food allergy symptom usually appears immediately after exposure to the food, where as an intolerance may not occur until hours or days later (Engle).

    Federal Regulations have attempted to insure proper food labeling.  According to the FDA, "If we find that labeling will not adequately protect consumers, we will take steps to prevent marketing of the product."  A site that will help insure food safety is the FDA's Recall list located here.

    Some of the most common food allergies are to milk, eggs, shellfish, and peanuts.  There are others such as soy, tree nuts, fish, and wheat.

*Clicking on (Tidwell) after the brief introduction to the food allergy will take you to that particular food allergy site where as the (Tidwell) in the bibliography  links to the general allergy page.*

    Milk

        Lactose intolerance is not an allergy but "an inherited deficiency of the enzyme lactase" (Engle).  A milk allergy will provoke skin reactions such as an itchy rash, digestive reactions such as vomiting, or respiratory reactions such as sneezing or even anaphylactic shock, which will be explained later (Tidwell).

    Eggs

        Most people who are allergic to eggs are allergic to the egg white, although some cases where people are allergic to the yolk.  Egg allergies may be seasonal due to the interrelatedness of pollens.  Symptoms from egg allergies include vomiting, asthma, or even anaphylactic shock, which again should be kept in mind for the later explanation (Tidwell).

        "The shellfish commonly known to cause allergic reactions include shrimp, crab, crayfish, lobster, oysters, clams, scallops, mussels, squid, and snails." (Tidwell).  The thing to remember about shellfish is that fish spoils easily, so a reaction to eating shellfish or fish in general may not be an allergic reaction but a reaction to the histamines that are released in a spoiled fish.

        Peanuts are incredibly dangerous to a person with a peanut allergy.  Even the smell of peanuts may cause a person to go into anaphylactic shock, and the worst of this information is that the occurrence of peanut allergies are rising (Tidwell).  Luckily for those with peanut allergies, peanut allergy awareness is increasing.  I noticed over the summer that all the local ice cream places have signs warning that peanuts are used in the shop. 

Pollen/hayfever

    Pollen is a microscopic reproductive organ of a plant.  It is carried through the wind in order to reproduce with another plant.  The lighter pollens are the most common allergens because they are carried by the wind easily.  The pollen count is a count of the number and kind of pollens that are in the air on any given day.  Click here for the pollen count today.  It is expressed in grains per meter (1).

    Hayfever is what many people call seasonal allergies.  "Physicians call it seasonal allergic rhinitis or pollinosis." (Rapaport).  Many people who claim to have hayfever may have an infection of some sort.  Like food allergies, hayfever symptoms come about suddenly.  Also, the attacks are "recurrent or constant" (Rapaport). 

Animals

    Pets

        About 15% of the population is allergic to pets (2).  Many people believe it is the fur that causes allergic reactions.  This is false.  The allergic reaction comes from proteins from the animal's skin, saliva, and urine.  These protein particles get into the air, and this is what causes the allergic reaction.  Physicians will most likely suggest that the only way to stop an allergic reaction to a pet is to give the pet away if it lives with you.  However, animals can be like a part of your family and giving them up may be more difficult than simply dealing with the annoying allergy.  Click here to find out how to keep your pet.

    Stinging Insects

        Most people do react to stinging insects.  The typical symptom is a red area where you were stung surrounded by a white ring.  This becomes itchy, and warm.  The reaction of a person who is "sensitive" to the sting can be more serious.  It is typically indicated by a dry cough and trouble breathing.  The eyes tend to swell, and the person is likely to experience hives all over their body.  The symptoms appear within minutes and the person must be taken to a doctor immediately to receive an injection of epinephrine and other treatments (Rapaport).

Other Allergy Information

Anaphylactic Shock

    This is classified as a Type 1 attack and is the most severe form of an allergic reaction.  It is characterized by respiratory symptoms (difficulty breathing), fainting, itching, swelling of the throat or other mucous membranes and sudden decline in blood pressure (Engle).  If not treated immediately it can lead to death within minutes.  The reaction is a pattern of the above responses that varies from person to person.  The first exposure to an allergen will not cause this reaction.  It happens only after sensitization has occurred.  The immediate treatment is an injection of epinephrine.

Most allergic reactions are not this severe.  Many are simply annoying, such as sniffling, sneezing, watery eyes, and itching.

Allergies in Children vs Adults

    Allergies tend to differ between children and adults.  Allergies in childhood often disappear with age where as adult allergies tend to be lifelong.    Cow's milk, eggs, and soy are some common childhood food allergies that may or may not disappear with age.  Adults tend to be allergic to shellfish and peanuts more often than children.  However, peanuts are becoming more and more prevalent in children as well.  Hayfever is typically an adult allergy and insect stings affect only 1% of children whereas it has been known to affect about 3% of adults (Engle). 

    Interestingly, many doctors believe that a child's allergies depend on the month in which they were born.  There is some evidence suggesting that the allergies do, in fact, differ depending on birth month.  In a Scandinavian study children born from February to April were more likely to be allergic to birch pollen and children born from April to May were more likely to be allergic to grass pollen (Engle).  These months are the months in which these pollens are most prevalent.

Asthma

    Asthma can be caused by many things, but this site only discusses the allergy causing asthma.  Asthma is a difficulty in breathing caused by bronchial obstruction.  It can get worse with each attack, and each attack makes the person more sensitive to another attack.   For example, a person who has seasonal allergies to pollen may, after a number of attacks, develop chronic asthma.  Also, if a person is allergic to animals and does not take the necessary steps to bathe the animal and clean the home often they can potentially develop chronic asthma.  Asthma can be treated and are more distressing than dangerous (Rapaport).  "[Asthma] kills more than 5,000 people a year in the United States." (Beebe).

Bibliography

1) Anonymous. (2000, October 1). Pollen Allergy. <http://www.ivillagehealth.com/conditions/autoimmune/articles/0,,165877_173895-1,00.html> (2004, September 9).   

2) Anonymous. (2004, May 16). Allergies to Pets. <http://www.hsus.org/ace/11778> (2004, September 9).

3) Anonymous. (2004, September 30). 20% of All Adults Believe They Have Food Allergies. 3) <http://www.medicalnewstoday.com/medicalnews.php?newsid=14223> (2004, September 30).

4) Beach, Steve. (2004). How Allergies Work. <http://health.howstuffworks.com/allergy.htm> (2004, September 9).

5) Brain, Marshall. (2004). How Your Immune System Works. <http://health.howstuffworks.com/immune-system5.htm> (2004, September 29).

6) Burrell, Robert.  1979. Experimental Immunology. 5th ed. Morgan Town WV. Burgress Plublishing Company.

7) Clark, William R.  1995.  At War Within.  The Double-Edged Sword of Immunity.  Oxford NY, Oxford University Press.

8) Engel, June.  1997.  The Complete Allergy Book.  Everything You Need to Know.  Buffalo, NY.  Firefly Books.

9) Formanek Jr., Ray. (2001 July/August). Food Allergies: When Food Becomes the Enemy. FDA Consumer Magazine. <http://www.fda.gov/fdac/features/2001/401_food.html> (2004, September 9).

10) Rapaport, Howard G. & Shirley matter Linde.  1970.  The Complete Allergy Guide.  New  York, NY.  Simon and Shuster.

11) Sompayrac, Lauren.  1999.  How the Immune System Works.  Boulder CO.  Blackwell Science, Inc.

12) Tidwell, Judy. (2004). Allergies. <http://allergies.about.com/> (2004, September 9).