Allergies have been progressively worsening over the years. There are primarily two factors that are responsible for the increasing prevalence of allergies in the population.
The first factor for the increase in allergies is secondary to the hygiene hypothesis. Although several hypotheses have been proposed for the increase in allergy, the hygiene hypothesis has been the most widely accepted.
The hygiene hypothesis suggests that patients or societies whose populations are cleaner, i.e. using more antibiotics and cleansing materials, are prone to increase their propensity for allergy. This increase in allergy is related to the concept that T cells influence the clinical nature of allergies. Therefore, the more clean a society is, the more likely the rate of allergies will increase.
The second factor is the genetic concept. If the father or mother have no allergies, there is at least a 10% chance of the child having allergies. If one of the parents has allergies, then there is a 25% chance of the child having allergies. If both parents have allergies, then there is a 50% chance of the child becoming allergic. The allergies that are inherited cause the propensity to become allergic but not to any specific antigen.
These two concepts somewhat explain the increasing prevalence of allergies in our society.
EPISODE 2
Food allergies have become more prominent in our communities as well. The most common food allergies in children are egg, milk and peanut. We will talk about each allergy in sequence throughout the next episodes. Food allergies have a tendency to be worse in children. There are less food allergies in adults.
Milk allergy is relatively common. Milk proteins, which include whey, casein, lactalbumin and lactoglobulin, are very common proteins that cause clinical symptoms.
Commonly milk allergies present during the introduction of formula early on in life and are present also later at 12 months with the introduction of whole milk. Some of the common symptoms with milk allergy may be colic, vomiting, diarrhea, worsening of eczema, hives or angioedema.
Interestingly enough, some patients may be able to tolerate milk that has been changed, boiled or processed, as opposed to whole milk. This has a lot to do with protein biology. Changing a protein by any physical force may allow the body to tolerate this product without giving the obvious clinical features.
Milk allergies may be tested either by scratch testing or by RAST testing. Avoidance is the only true treatment of milk allergies. With complete avoidance, milk is usually added back to the diet without difficulty.
EPISODE 3
Food allergies are extremely common in children. One of the foods that patients can be sensitized to is egg. Egg avoidance is very difficult since it exists in almost every food product that is available.
Egg can also be known as ovalbumin. The egg allergy is noted early in life. The family usually notes rashes after ingestion of pastas or other egg products. The AAP recommends that eggs should not be started until after 12 months of age. At this point we note that the symptoms to egg exposures are prominent.
Egg allergies may cause a variety of symptoms. Typically it may worsen eczema. Other symptoms of egg allergy may be hives, diarrhea, anaphylaxis or other manifestations. Strict avoidance is necessary in order to prevent any further occurrences. Avoidance is also the only treatment.
In addition, various vaccines are made on egg components. These include the flu vaccine and yellow fever. The MMR is also one of the injections that are grown on eggs. The most recent Red Book for the American Academy of Pediatrics suggest that egg allergies should not prevent people from getting the MMR, although they do state that if there is a high level egg allergy, that one should consult the allergist.
EPISODE 4
Peanuts are a very common allergy in our community. Peanuts are actually legumes and are related to peas, string beans, lentils and other beans. The actual cross-reaction clinically is approximately only 1%. Therefore, only 1 out of 100 patients with peanut allergies may experience this cross-reaction. Cross-reactions are commonly much milder.
Peanuts come in various forms in our diet. They may be found in cereals, snacks, candies and baked goods. They are found in various forms of peanut butter. In some cases patients with peanut allergies tolerate peanut butter because of the way the peanut has been processed. It is still not recommended that patients with peanut allergies eat peanut butter even if it is tolerated.
Peanut allergies may cause severe reactions. Some of the most severe reactions include anaphylaxis, which has been reported with peanut ingestion. Avoidance and proper measures, i.e. epinephrine and emergency plan, are necessary for those people who are reactive.
Peanut allergies may come in a systemic form after ingestion. If a family member is ingesting peanuts and kisses the individual who is allergic, a large welt may occur at the site. Therefore, there are two ways that peanuts may be problematic to these individuals. One is the ingestion of peanuts, and the other may be the topical exposure. The topical exposures are not frequently anaphylactic unless placed in the mucous membrane.
There is at present no known resolution of peanut allergies, although people with mild peanut allergies may eventually outgrow the peanut allergy, but this will only be reached with consulting an allergist. Patients with more severe peanut allergies will most likely keep their peanut allergy for life.
EPISODE 5
Cross-reactions within food groups are fairly common in patients with allergies. On occasions patients with pollen allergies will experience an itchy roof of the mouth when exposed to any of the raw fruits, i.e. tomato, peach, pear, honeydew, watermelon, cantaloupe and apple. This is secondary to the exposure of a protein called protophylin, which is present both in the fruit and the pollen. When the patient eats the fruit their body thinks that they are eating pollen and, therefore, they develop a reaction.
Patients who are reactive to latex may also have reactions to avocado, papaya, tomato, cherry, etc. These shared properties of the fruits and latex confuse the body and convince the body that they are truly eating latex. It is, therefore, possible to become allergic to latex in two ways. The first way is primarily becoming allergic to latex and cross-reacting to these foods, in which case testing to the foods would be negative. The other way is becoming primarily allergic to the foods and then secondarily cross-reacting to latex. In this case, the testing for latex would be negative.
Mammalian milks in general cross-react. It appears that goat’s milk and other types of milk are very similar to cow’s milk. There is less familiarity in the proteins in cow’s milk and horse milk.
Other cross-reactions occur in nature. The cross-reactions are extremely dependent on the individual rather than any list. Some patients may react to all the cross-reactions, and some will react to none. For further information consult your allergist on this topic.
EPISODE 6
Clinical symptoms of allergies are as a result of a complicated molecular process.
The patient, in order to develop allergy symptoms, must be exposed. Therefore, the patient who has allergies is allergic to something that they have seen before. Allergies are never produced from the first exposure.
The first time the patient gets exposed to the allergen, the patient produces an IgE. This IgE is specific for that allergen, i.e. peanut, milk or ragweed. This IgE then floats throughout the bloodstream and eventually coats mast cells. Once it coats the mast cell, the mast cell then acts as a little time bomb that may float to the skin, the lungs, the nose or to any organ system. After the second, third or fourth exposure of the allergen, i.e. milk or peanut, the IgE is cross-linked by that allergen on the mast cell. Once this cross-linking occurs there is an explosion of histamine that is released. Histamine is responsible for the swelling, the itchiness and the wateriness that one experiences from an allergic reaction. Again, the typical clinical symptoms are only seen after the second, third, fourth or multiple exposures to the antigen.
Photo provided by Dr. Hostoffer depicts a child suffering from angiodema urticaria - reaction to peanuts
For more information, please contact your allergist on these allergic processes.
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Dr. Robert W. Hostoffer Jr.
Allergy Immunology Associates, Inc.
1611 S. Green Road #231
South Euclid, OH 44121
216-381-3333
