notes by dr Claudio Italiano
The term allergy derives from the Greek and literally means "altered reaction". The allergy is, that is, an inappropriate and harmful response of the body's defense mechanisms towards substances otherwise harmless to non-allergic subjects but which can become deadly for those allergic. The immune system of the allergen undergoes an abnormal and exaggerated reaction when it comes into contact with these substances, the so-called allergens, present in the environment in which we live (pollens, mites, molds, animal epithelium, insect poison, nickel , etc.) or that we introduce with foods and drugs. Allergy manifests itself in a wide variety of symptoms, from sneezing to tearing, from rhinorrhea to cough, from swelling of the lips to asthma, from urticaria to angioedema, from eczema to pruritus, from vomiting to diarrhea to symptoms of extreme gravity such as anaphylactic shock and glottal edema. The allergens are the foreign substances capable of producing in the organism an allergic reaction, that is a disproportionate and out of place reaction, mediated by substances called antibodies of the IgE type, responsible for different clinical manifestations. Allergic substances are extremely numerous and can be divided into: -Allergen by inhalation: pollens, mites, dermatophagus and other parasites present in environmental powders, derivatives of animal origin (forfore, hairs, etc.), fungal spores, etc.
- Allergens from ingestion: food, of animal or vegetable origin, different
chemical substances (eg food additives), drugs? Injection or puncture allergens:
drugs (eg anesthetics), insect poisons.
- Contact allergens: different chemicals, cosmetics, drugsCome si manifesta l'allergia?
Allergic rhinitis is a condition characterized by a typical symptomatology:
series of sneezing, sometimes 10-20 consecutive (frequently preceded by itching
or burning nasal), watery secretion, nasal obstruction that often forces to
breathe through the mouth. There may be redness of the conjunctivae,
particularly intense in pollen allergies. Symptoms often have a constant mode of
onset, in relation to seasonal allergens. The duration of the single crisis can
be very short, even for a few minutes, or it can be prolonged for many hours. In
the province of Belluno, this disease alone or associated with ocular disorders
represents over 50% of the allergic respiratory pathology. This percentage rises
to 88% if we also consider the forms associated with bronchial asthma.
It is characterized by shortness of breath of varying intensity and duration. The patient feels a sensation, more and more intense and harassing, suffocation and need of air and he feels the painful impression of a "grip that tightens the chest". The breath and sibilant. The cough may precede, accompany or mark the end of the asthmatic attack. Access can have a variable duration, usually of hours, sometimes a few minutes, rare times more days.
The pollens are the first identified allergenic agents and the disease that goes
by the name of pollinosis and among the long-known allergic expressions, since
the V century BC. The picture of the so-called "hay fever" was accurately
described in 1819 by Bostock, who was affected and noted the seasonal renewal of
rhinitis, conjunctivitis and asthma, which was often accompanied by a fleeting
feverish rise. Precisely the feverish symptomatology has long been misunderstood
and only now finds its rational justification in particular substances called
interleukins that participate in the allergic reaction. The pollen grains are
special reproductive cells of the size of a few thousandths of a millimeter
corresponding, in plants, to the reproductive cell of the male animal.
Pollinosis is the most common and frequent allergic disease and includes various
clinical manifestations (especially nasal, ocular and bronchial) that occur with
seasonal periodicity, during the period of pollination, in subjects susceptible
to pollen of certain plant families. It can be calculated, even if there are no
precise statistical data, that in Italy at least 5% of the population present
more or less evident clinical manifestations of pollinosis; there would
therefore be, in our country, over 2 million people affected by the disease.
Among the allergic patients who are followed by the Belluno Hospital Allergology
Service, 51% suffer from this disease.
Often, in some subjects, cross-reactivity towards pollen of some families and various plant foods is found. In these cases, contact with these foods causes an allergic oral syndrome with irritation phenomena on the lips and the oral cavity. In birch and hazelnut pollinosis, hypersensitivity to apple, pear, apricot, walnut, cherry, banana, hazelnut, fennel and carrot is frequently found. People who suffer from allergies to composites often have hypersensitivity to celery In grass pollinosis there may be a reactivity with tomatoes, melons, watermelons, oranges and kiwis.
The diagnosis of allergic diseases has particular characteristics and aspects. In fact, the diagnostic problem does not end with the detection of the disease, usually not particularly difficult, but mainly consists in the recognition and demonstration of the causal factors that determine the disease. The patient's history is of fundamental importance for an orientation on the suspected allergens that must then be identified by specific diagnostic tests. The skin tests are, among the specific diagnostic investigations, those most frequently practiced and still retain an undisputed validity if performed by expert hands and if properly evaluated. Therefore they should be considered as a first level method in the diagnostic approach to the allergopathic subject. They are based on the principle that if an individual has specific IgE to a certain allergen, these are, at least in part, linked to the white blood cells and to special skin cells, including skin cells, called mast cells.
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