Allergy

The issue of allergy is extremely important because allergic reactions in our population occur very frequently and this trend is increasing. In addition the problematic of allergies is very complex and it is not easy to write some coherent article committed to this issue. First it is necessary to clarify certain terms such as allergy, atopy and allergen.

 

Allergy itself is not a specific disease. It is a condition where the immune system of human body responds to normal stimuli by inappropriately exaggerated defensive reaction which can have a variety of symptoms that can affect various body systems and may even endanger human life itself. An allergy can be obtained or inherited.

 

Atopy is a genetically given condition which deepens risk of allergic reactions. A man with a history of atopy can be completely healthy and have no allergic symptoms but special tests can detect an increased excitability of his or her immune system. During life of such atopic person the atopy may change at any time in allergy with classic allergic manifestation. Number of atopic people in population of developed countries is huge and we estimate it up to 40 % of general population.

 

Allergen is a stimulus (usually some chemically definable substance) which is capable of triggering an allergic reaction. Typical allergens include pollen, dust, dust mites, products of the sebaceous glands of domestic animals, drugs, snake and insect venoms and last but not least - food (in this case we talk talking about food allergy).

Allergic reactions

Allergic reactions have two main forms - acute and chronic.

 

Acute allergic reactions emerge shortly after a contact with proper allergen. First contact with such allergen causes no visible problems but it is only an illusion. During first contact our body becomes sensible towards the allergen. Certain white blood cells, B lymphocytes, convert into active plasma cells and begin to produce high quantum of IgE antibodies which are targeted against chemical substance of the allergen. These antibodies bind to mast cells and with this the reaction ends.

 

During next contact with the same allergen its molecules bind to IgE antibodies bound to mast cells. Mast cells are activated and release their content – a number of inflammatory substances including histamine. These substances cause a variety of symptoms of allergic reactions. They have a strong effect on vascular walls and increase their permeability for intravascular blood plasma. Following the leakage of fluid from blood vessels into surrounding tissues usually causes swelling.

 

Chronic symptoms appear when there are frequent allergic attacks (i.e. recurrent acute reactions) and long-term effects of allergens. Inflammatory mediators that are released during allergic attacks damage tissues. This results is a chronic impairment of the target tissue which may be permanent. Exact symptoms depend on damaged tissue or organ system type.

 

What is the reason of allergic reactions development? That is still not entirely clear. Allergies can develop at any age and even against those substances which have never triggered allergic reaction before.

 

Did a bee sting you as a child and nothing happened? Well it doesn’t mean that the next sting can not cause a serious reaction. And on the contrary allergies can cease without any obvious reason.

Symptoms of allergic reaction

They are extremely variable. According to the particular manifestations we can distinguish different conditions emerging on the basis of allergic reaction.

Allergic rhinitis

Main symptoms include itchy nose, sneezing and mucus discharge from nostrils. It is very often season dependent.

Bronchial asthma

This is more serious. In this case lower respiratory tract is affected. Main symptoms are acute shortness of breath, cough, whistling and choking.

Urticaria

It is a way of skin related allergic reaction. Skin becomes red and reddish and often itchy rash occurs.

Atopic dermatitis

This is a chronic disease associated with long-term allergic reactions. The manifestation is annoying itchy skin involvement.

Allergic symptoms in the digestive tract

In case of irritation of intestinal wall by an allergic reactions, diarrhea and other digestive problems often occur.

Allergic conjunctivitis

It is an unpleasant burning sensation and redness of the eyes. Affected person often has swollen eyelids. Allergic conjunctivitis is usually accompanied with allergic rhinitis.

Anaphylactic shock

It is an extremely dangerous overall reaction of human body to an allergen. It is characterized by symptoms of asthma (choking) and a massive allergic reaction leading to increased permeability of blood vessel walls. Blood fluid (plasma) escapes into the tissues outside the blood vessels (swelling) and blood circulation starts to fail. That causes a disruption of oxygen transport to tissues. This type of allergic reaction could be fatal and can emerge without warning. A bee sting is a great example. There is only a little dose of venom which can not poison a human but a strong anaphylactic reaction can kill him within minutes.

Diagnosis

It is important to find any of symptoms listed above and outer factors which trigger them. Family history is also of a great importance because allergies are strongly influenced by genetics. Blood test are important, we look for elevated levels of IgE antibodies which are typical for allergy sufferers. The best method, however, are the skin tests. They are performed by a skilled doctor. The doctor applies samples of known allergens carefully in the skin of a forehand and after some time he checks skin response to those allergens. The response is measured by perimeter of a local bud which can emerge. More specific diagnostic methods can be found in articles about certain allergic diseases.

Prevention

There is no totally reliable protection. Some protection is probably achieved by correct stimulation of the immune system in children. The point is that children should not be brought up in complete sterile clean environment. Sterile environment leads to insufficient stimulation of immune system and children may start to react sensitively to otherwise normal stimuli, i.e. with an n allergic reaction. As soon as the allergy against particular allergen occurs it is best to avoid this substance if possible.

Treatment

If there is only a mild allergic reaction – red eyes, runny nose, skin itching etc. – antihistamine drugs are the bets solution. They counteract the effects of that of histamine which is an important part in allergic reaction mechanism (as noted above). However many of them have sedative effect of various strength. In severe allergic reactions, such as in anaphylactic shock, antihistamines are not enough efficient. In such conditions corticosteroids are administered intravenously as very effective and quick weapon against allergic reaction. More specific methods of treatment can be found in articles about particular clinical forms resulting from allergic reaction (as noted above).