The following points highlight the top eight types of common allergies in Humans. The types are: 1. Pollen Allergy 2. Food Allergy 3. Infection Allergy 4. Serum Reactions 5. Delayed Serum Reactions 6. Atopy 7. Drug Idiosyncrasies 8. Binding Power of Tissues.
Common Allergies: Type # 1. Pollen Allergy:
The pollen (sperm cells) of many plants—grasses, roses, rag weed—may cause allergy in some persons. When the proteins of the pollen come in contact with nasal and respiratory mucous membrane of the individuals, they are absorbed locally and set up a hypersensitivity condition of these tissues.
When the individual inhales later more of the pollen proteins, the nose and throat become irritated, swollen and oedematous. Because of the severity of the reactions against pollen, there develop a symptom of severe “cold” which is commonly known as “hay fever” or nose fever. These conditions may be relieved by antihistaminic and nasal decongestants.
Common Allergies: Type # 2. Food Allergy:
A person may become sensitized to certain foods (strawberries or cod fish). Due to a slight gastrointestinal irritation, lesion or disturbance, some of the food is absorbed undigested through the stomach or intestinal wall into the blood. The result is the same as if the protein has been injected.
The next time or perhaps every time the same person eats strawberries or cod fish, he will react very violently. There will be allergic manifestation in the form of rash or blotches on the skin which itch persistently. These conditions are known as “hives.” Some other victims may exhibit nausea, vomiting, gastrointestinal irritation and general symptoms. Antihistaminic are useful in these conditions.
Common Allergies: Type # 3. Infection Allergy:
Due to the microbial proteins entering into the blood stream certain cells of the body may become sensitized to these microbial proteins resulting into the delayed allergy. A person suffering from tuberculosis may become allergic to tuberculosis.
The relapses in rheumatic fever are due to repeated allergic responses (with damage to heart muscles) to reinfection with certain streptococci to which the patient is already allergic. Allergy may also develop in viral, fungal, worm infections, such allergy is called as Infection allergy. Most of the damaging effect of infectious diseases is due to infection allergy.
Common Allergies: Type # 4. Serum Reactions:
There are two forms of serum reactions:
One is acute and serious form resembling anaphylaxis characterised by collapse, dyspnea, occurring after a few minutes after the injection of therapeutic serum (e.g., diphtheria antitoxin); the other one is milder, delayed form known as serum sickness.
Both forms depend upon the precipitin in the patient. Either type of serum reaction is due to animal (horse) protein in the therapeutic serum, not to the specific antitoxin. Symptoms are chill, nausea, extensive painful itching hives or serum rash. Pain in the joints may occur later. If the patient is serious, there may be fatal end.
Common Allergies: Type # 5. Delayed Serum Reactions:
Serum sickness may appear after ten to fifteen days after a therapeutic use of horse serum. It is assumed that, during this period, the precipitin to horse serum protein may accumulate in the tissues. After reaching a certain concentration, the precipitins react with the proteins (even in residual portion) of the therapeutic horse serum which still remain in the body.
If the therapeutic horse serum is to be given parenterally, a preliminary skin test for hypersensitiveness to horse serum may be performed as described below. If the test is positive, the patient should be desensitized by giving a number of a very small (0.1 to 1 ml) dose of the serum at intervals of an hour or so before the main injection.
The possible shock to the patient is lessened. This process is called as “desensitisation.” Persons with previous injections of serum usually require desensitisation. Sometimes, even in the persons who have not had the previous injections of serum, the serum sickness may also occur.
Common Allergies: Type # 6. Atopy:
Some individuals inherit not allergy itself, but a certain increased tendency to form reagins and thereby to develop allergic reactions (i.e., asthma, hay fever) and perhaps certain forms of arthritis and rheumatic heart disease. These persons are called atopic (and are called ‘unfortunate’).
Common Allergies: Type # 7. Drug Idiosyncrasies:
Certain plant perfumes, cosmetics, drugs, rubber goods, dyes etc. may also cause immediate allergy-like responses (hives, dermatitis, asthma) which may be previously dependent on specific antibodies at all. These allergy-like reactions restricted to only to certain individuals are known as drug idiosyncrasies. The mechanism is not yet well- understood.
Common Allergies: Type # 8. Binding Power of Tissues:
Because of natural infections or artificial injection of certain antigens (bacterial cells and exotoxins), cutaneous and mucosal tissue often acquire the property of combining with and holding fast to these specific antigens entering the body. This is a defense mechanism and is probably one manifestation of allergy. These tissues are said to be sensitized to the antigens.
Once sensitized, the tissues tend to hold on and bind to these specific antigens, infections or toxins to prevent their further spread from the site of localisation whenever they gain entry into the body. The tissues may be damaged locally/ but generalized infections or intoxication is prevented.
The binding power of the tissues is the basis for the beneficial effect of several methods of artificial immunization, as for example-Bacillus Calmette Guerin (BCG) vaccine. This is also of great importance in resistance to brucellosis, syphilis, and other chronic diseases.