Allergy, types and tests for detection.

1. By Arijit Pani
ALLERGY
CAUSES AND TESTS FOR DETECTION

2. What is an Allergy?
Allergies are a number of conditions
caused by an exaggerated response of
the immune system to something in the
environment that usually causes little or
no problem in most people.
These are harmful immune responses
that produce tissue injury and may cause
serious diseases like hay fever, food
allergies, atopic dermatitis, allergic
asthma and anaphylaxis.

3. What is an Allergen?
An allergen is a type of antigen that produces an abnormally vigorous immune response in
which the immune system fights off a perceived threat that would otherwise be harmless to the
body giving rise to allergies.
It is an antigen capable of stimulating a type-I hypersensitivity
reaction in some individuals through Immunoglobulin E (IgE)
responses.
Sensitivities vary widely from one person to another. A very
broad range of substances can be allergens to sensitive
individuals.

4. Types of Allergen
Aeroallergens
• Airborne particles we inhale
• Example: Mold spores, dust, pollen, animal dander etc.
Insect Bites and Stings
• Venom in insect bites and stings
• Example: Wasps, hornets, bees etc.
Food
• Different food items we consume
• Example: Milk and other dairy products, egg, wheat, soy, peanuts etc.
Medicines
• Usually medications that treats infection
• Example: Different antibiotics.
Chemicals
• Chemical agents present in products of household use
• Example: Dyes, cosmetics, laundry detergents etc.

5. Allergy Does Not Affect Everyone
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6. Why are some people allergic?
 Some people inherit a tendency to be allergic from
one or both parents. But, the allergen to which a
person would be allergic to is not hereditary.
 In addition, exposure to allergens at times when the
body’s defenses are lowered or weakened, such as
after a viral infection or during pregnancy, seems to
contribute to developing allergies.
Why me??

7. Most Common Causes For Allergies

8. Pollen Allergy
 Plants produce tiny round or oval pollen grains to reproduce.
 In some species, the plant uses the pollen from its own flowers to
fertilize itself. Other types must be cross-pollinated. Air is used as a
dispersal medium in cross pollination.
 The types of pollen that most commonly cause allergic reactions are
produced by plain-looking plants (trees, grasses, and weeds) that do
not have showy flowers.
 Some of the common sources of allergenic pollen are produced by
ragweed, timothy grass, oak, mountain cedar etc, giving rise to
conditions like hay fever or allergic rhinitis.

9. Mold Allergy
 Mold spores are important airborne allergens only if they are abundant.
 When inhaled, tiny fungal spores may cause allergic rhinitis. Sometimes they
cause asthma and other lung disorders.
 Hot spots of mold growth include:
• damp basements and closets
• bathrooms
• places where fresh food is stored
• refrigerator drip trays
• house plants
• air conditioners
• mattresses etc
 In general, Alternaria and Cladosporium are the molds most commonly found
both indoors and outdoors responsible for causing allergies.

10. Dust Mite Allergy
 Dust mite allergy is an allergy to a microscopic organism that lives in the
dust found in all dwellings and workplaces.
 Dust mites are most common cause of perennial allergic rhinitis. House
dust mite allergy usually produces symptoms similar to pollen allergy and
also can produce symptoms of asthma.
 House dust mites live in bedding, furniture and carpets. They thrive in
summer and die in winter.
 Dead dust mites and their waste products are proteins which provoke the
allergic reaction.

11. Bacterial Allergy
 Bacteria are common causal organisms of serious allergic conditions.
 Bacterial conjunctivitis is usually caused by Staphylococcus aureus,
Streptococcus pneumoniae, Haemophilus sp, Chlamydia
trachomatis etc.
 Neisseria gonorrhoeae causes gonococcal conjunctivitis, which usually
results from sexual contact with a person who has a genital infection.
 Acute Urticaria (hives) are often caused by bacterial pathogens infecting
the skin of individuals.
 Staphylococcus aureus, Kelbsiella pneumoniae and Diplococcus
pneumoniae are often found to be causing allergic rhinitis and bronchial
asthma.

12. Virus and Allergy
 Allergic reactions like development of rash, hives etc have
often been witnessed during a viral invasion like Herpes
virus infection.
 A recent publication in Nature Immunology by Dahl et al.
reports that influenza infection can enhance allergic
responses in the lungs.

13. Food Allergy
 A wide variety of foods can cause allergic reactions like
milk, soy, eggs, wheat, peanuts, tree nuts, fish, and shellfish.
 Rates of allergies differ between adults and
children. Some allergies can sometimes be outgrown by children.
 In case of egg allergies the sensitivity is usually to proteins in the
egg white, rather than the yolk.
 Milk-protein allergies are most common in children. Some people
are unable to tolerate milk from goats or sheep as well as from
cows, and many are also unable to tolerate dairy products such
as cheese.
 Roughly 10% of children with a milk allergy will have a reaction
to beef. Beef contains a small amount of protein that is present in
cow's milk.

14. Overview of an Allergic Reaction

15. An allergic reaction : Overview
A person comes in contact with an
allergen, the immune system gets
ready to attack.
A large number of antibody, IgE
molecules get generated and
released.
IgE molecules attach to the
receptors present in mast cell.
The IgE-primed mast cell releases
granules and powerful chemical
mediators, such as histamine,
cytokines, granulocyte macrophage
colony-stimulating factor (GM-CSF),
leukotrienes, heparin, and many
proteases into the environment
These chemical mediators cause the
characteristic symptoms of allergy
The onset of allergic reaction.

16. An allergic reaction : Overview

17. Signs and Symptoms

18. Redness and itching of
the conjunctiva (allergic
conjunctivitis, watery)
Swelling of the
nasal mucosa (allergic rhinitis)
runny nose, sneezing.
Feeling of fullness, possibly
pain, and impaired hearing.
Rashes, such
as eczema and hives
(urticaria).
Sneezing,
coughing, bronchoconstriction,
wheezing, sometimes outright
attacks of asthma.
Abdominal
pain, bloating, vomiting,
diarrhea.

19. Tests For Detection

20. Different Diagnostic Tests for Allergy Detection
Skin Prick Testing
• A series of tiny punctures or pricks made into the patient's skin.
• Small amounts of suspected allergens or their extracts (e.g., pollen, grass,
mite proteins, peanut extract) are introduced to sites on the skin marked with
pen or dye.
• Common areas for testing include the inside forearm and the back.
• If the patient is allergic to the substance, a visible inflammatory reaction will
usually occur within 30 minutes. This response will range from slight reddening
of the skin to a full-blow hive.
.
Patch Testing
• Patch testing tests for delayed reactions.
• It finds the cause of skin contact allergy, or contact dermatitis.
• Adhesive patches, usually treated with a number of common allergic
chemicals or skin sensitizers, are applied to the back.
• The skin is then examined for possible local reactions usually at 48 hours
after application of the patch, and again two or three days later

21. Different Diagnostic Tests for Allergy Detection
Blood Testing
•Adults and children of any age can take an allergy blood test.
•Allergy blood tests are safe as the person is not exposed to any allergens
during the testing procedure.
•The test measures the concentration of specific IgE antibodies in the
blood. The higher the IgE antibody value, the greater the likelihood of
symptoms.
•The quantitative allergy blood result can help determine what a patient is
allergic to, predict and follow the disease development, estimate the risk of
a severe reaction, and explain cross-reactivity.
•Laboratory methods to measure specific IgE antibodies for allergy testing
include enzyme-linked Immunosorbent assay (ELISA, or EIA),
radioallergosorbent test (RAST) and fluorescent enzyme
immunoassay (FEIA).

22. Laboratory Methods To Measure IgE Antibodies
Enzyme linked immunosorbent assay (ELISA) Radioallergosorbent test (RAST)

23. Prevention of Allergies

24. Avoiding the allergy triggering
items like nuts, eggs, wheat,
gluten, soya or milk etc, in
case of food allergy.
Avoiding outdoors during the
season of pollen dissemination
in the environment, avoidance
of pets and animal dander and
keeping the house clean and
free of dust and dust mites.
Good and dry ventilation, dry
and clean clothes storage in
the wardrobes and removal of
damps from the house helps
prevent allergies from moulds
A high intake of antioxidants,
zinc, and selenium during
pregnancy may help prevent
allergies.
Probiotic supplements taken
during pregnancy or infancy
may help to prevent atopic
dermatitis.

25. Medication

26. Medications to Treat Allergy
Several medications may be used to block the action of allergic
mediators, or to prevent activation of cells and degranulation processes.
The commonly used medications include:
•Antihistamines
•Glucocorticoids
•Epinephrine (adrenaline)
•Mast cell stabilizers
•Antileukotriene agents
•Anti-cholinergics
•Decongestants to impair eosinophil chemotaxis.
•Antibiotics such as Penicillin and its derivatives can be used to treat
bacterial allergies.

27. Thank You