ALLERGY

Yousra Imran

2011-ag-1053

M. Sc 3rd

Allergy

Allergy is a specific immunological reaction to a normally harmless substance, one that does not bother most people. It is often characterized by redness of the skin, warmth, swelling, and pain and inflammation of respiratory track..

Allergen

A substance capable of sensitizing the body in such a way that an unusual response occurs, in hypersensitive person

TYPES OF ALLERGEN

Allergens that cause allergic reactions include:

Pollens

House dust mites

Mold spores

Food

Latex rubber

Insect venom

Medicines

Fragrance

INTRODUCTION

The term allergy was first defined in 1906 by von Pirquet in describing a changed reaction in the body. An unusual response of a person to a substance that is harmless to others, the individual is said to be allergic.

500 million people suffer from food allergy

300 million suffer from asthma

Excessive cause of allergy is over-sanitation, utilization of antibiotics & less exposure to viruses and bacteria in childhood.

Allergy involves an exaggerated response of the immune system.

Immunology Of Allergy

• Elevated IgE levels seen in allergy and parasitic infection.

• Binds to mast cells and basophils.

• Often specific for harmless environmental factors – allergens.

Cont…..

Immune system activated when pathogen

enters

B-cells produce antibodies-immunoglobulin

Five types of immunoglobulin in which IgE is important in allergic reaction.

Attached to mast cell at determine site-crosslinking

COMMON SYMPTOMS OF ALLERGY

AFFCTED ORGANS SYMPTOMS

Nose Swelling of nasal mucosa

Sinuses Allergic sinusitis

Eyes Redness and itching of conjunctiva.

Airways Sneezing, coughing, bronchoconstriction, wheezing, dypsea and asthma.

Ear Feeling of fullness, possibly pain and impaired haring.

Skin Rashes such as eczema and hives

Gastrointestinal pain Abdominal pain, bloating, vomiting and diarrhea

Causes of Allergy

Foods

Non-food proteins

Toxins interacting with proteins

Airborne allergen

Genetic basis

Mechanism of allergy

o Acute response

o Late-phase response

Acute response

Late-phase response

Allergic disorders

Atopic dermatitis

Allergic rhinitis

Asthma

Food allergy

Anaphylaxis

20

The Allergic Disorders

.

Food Allergy

Atopic dermatitis(Eczema)

Allergic rhinoconjunctivitis(hay fever)

Asthma(cough;wheeze)

Gastrointestinal symptoms

Nervous system:HeadachesIrritability

Anaphylaxis

Muscle pain

Atopic dermatitis(Eczema)

Chronic inflammatory skin disorder

Affects at least 15% of children & up to 10% of adults

Atopic dermatitis is often the first manifestation of allergic disease & many patients may develop allergic rhinitis and asthma later in life

Symptoms:

rashes are dry, scaly and itchy

In infants & young children, the rashes appear on the face, neck, cheeks and scalp

In older children & adults-appear on the folds of the forearms, the inner elbows and behind the knees

Factors that make the symptoms worse include temperature, humidity, irritants, infections, food, inhalant and contact allergens and emotional stress

Treatment:

Topical corticosteroids , lifestyle changes & the use of medications

Types of Eczematous Dermatitis

Contact Eczema

Seborrheic Eczema

Nummular Eczema

Neurodermatitis

Stasis Dermatitis

Dyshidrotic Eczema

Contact Eczema

Contact eczema is a localized reaction that includes redness, itching & burning in areas where the skin has come into contact with an allergen

Due to the vast number of substances with which individuals have contact, it can be difficult to determine the trigger for contact dermatitis.

The condition is sometimes referred to as allergic contact eczema , if the trigger is an allergen and irritant contact eczema.

People who have a history of allergies have an increased risk for developing contact eczema.

Seborrheic Eczema

Seborrheic eczema is a form of skin inflammation of unknown cause.

The signs and symptoms include yellowish, oily, scaly patches of skin on the scalp, face & occasionally other parts of the body. Dandruff and "cradle cap" in infants.

It is common place for seborrheic dermatitis to inflame the face at the creases of the cheeks and/or the nasal folds.

This condition tends to run in families. Emotional stress, oily skin, infrequent shampooing, and weather conditions are felt to be factors for developing seborrheic eczema.

One type of seborrheic eczema is also common in people with AIDS.

Nummular Eczema

Nummular eczema is characterized by coin-shaped patches of irritated skin -- most commonly located on the arms, back, buttocks, and lower legs -- that may be crusted, scaling, and extremely itchy.

occurs most frequently in elderly men and women.

usually a chronic condition.

A personal or family history of atopic dermatitis, asthma, or allergies increases the risk of developing the condition.

Neurodermatitis

chronic skin inflammation caused by a scratch-itch cycle that begins with a localized itch that becomes intensely irritated when scratched.

Women are commonly affected, frequent in people 20-50 years of age.

This form of eczema results in scaly patches of skin on the head, lower legs, wrists, or forearms.

Over time, the skin can become thickened and leathery.

Stasis Dermatitis

skin irritation on the lower legs, generally related to the circulatory problem known as venous insufficiency, in which the function of the valves within the veins has been compromised.

exclusively in middle-aged and elderly people, with approximately 6%-7% of the population over 50 years of age being affected by the condition. The risk is higher in advancing age.

Symptoms include itching and/or reddish-brown discoloration of the skin on one or both legs.

ulcers may develop in affected areas.

lead to an increase in fluid buildup (edema) in the legs.

Dyshidrotic Eczema

irritation of the skin on the palms of hands & soles of the feet characterized by clear, deep blisters that itch and burn.

Cause are unknown.

also known as vesicular palm plantar dermatitis, dyshidrosis, or pompholyx.

occurs in up to 20% of people with hand eczema & common during the spring & summer months & in warmer climates.

Allergic rhinitis

an IgE-mediated inflammation of the nasal mucosa in response to outdoor and indoor allergens

affects between 10 to 30 percent adults and more than 40% of children worldwide

Causes:

pollens, dust mites, molds and insects

o Symptoms:

sneezing, runny or stuffy nose, teary eyes and itchy nose, throat or skin

Classification of Allergic Rhinitis

Based on frequency & severity of symptoms

mild intermittent

mild persistent

moderate/severe intermittent

moderate/severe persistent

Based on type of allergen

perennial

seasonal

Asthma

life-long inflammatory disease characterized by airway hyper responsiveness & airflow obstruction

the inner lining of the airways become inflamed and the muscles surrounding the airways tighten up mucus glands in the airways secrete thick mucus-cause the airway to narrow - leads to difficult breathing, shortness of breath, cough and wheezing

Children with allergies have a 30% increased risk of developing asthma

Genes play an important role in the susceptibility to develop asthma

Types of Asthma Allergic (Extrinsic)

more common (90% of all cases) & typically develops in childhood.

Approximately 80% of children with asthma also have documented allergies.

there is a family history of allergies.

Allergic asthma often goes into remission in early adulthood. However, in 75% of cases, the asthma reappears later.

Types of Asthma: Non allergic (Intrinsic)

represents about 10% of all cases.

develops after the age of 30 & is not typically associated with allergies.

Women are more frequently involved , cases respiratory tract infection.

The condition can be difficult to treat and symptoms are often chronic and year-round.

Asthma Exams, Tests & TreatmentExams and tests:

lung (or pulmonary) function tests (spirometer, or peak flow meter) which measure lung function.

Blood tests give a picture of your overall health; specific tests also measure levels of immunoglobulin E (IgE), a key antibody that's released during an allergic reaction.

X-ray exam of you in order to visualize the structures inside your chest, including the heart, lungs, and bones.

Treatment:

bronchodilators/ inhalers

Anaphylaxis

Anaphylaxis is the most severe allergic reaction and is potentially life threatening.

Anaphylaxis is rare. The vast majority of people will never have an anaphylactic reaction.

The most common causes of anaphylaxis include drugs, such as penicillin, insect stings, foods, X-ray dye, latex, and exercise.

The symptoms of anaphylaxis may vary and can include hives, tongue swelling, vomiting, and even shock.

Allergy diagnosis

Skin prick test

Blood Test

Patch test

Skin prick test

Blood Test

Patch test

Treatments

Allergen immunotherapy

Rush immunotherapy (RIT)

Homeopathic remedies

Avoiding exposure

Allergen immunotherapy

Rush immunotherapy (RIT)

very quick

shots given every few hours, instead of every few days or weeks, to increase the tolerance to an allergen

patients receiving both Omalizumab (monoclonal antibody) & RIT had fewer adverse symptoms than those receiving either treatment alone

Pretreatment of Omalizumab enhances both the efficacy & the safety of Rush immunotherapy

Homeopathic remedies

Lycopodium, Pulsatilla and sulfur can be useful in reducing allergic respons

Intestinal commensal bacterial flora or eating the right kind of yoghurt can also be used for inhibiting the development of allergic responses to food related allergens

Avoiding exposure

personal hygiene may be the best alternative for reducing allergies

Persons prone to respiratory symptoms should avoid exposure to allergens; they should cover their noses or wear pollen/dust masks while going outside or exercising during pollen season

Air purifiers and cleaning of air vents and duct scan help in cleansing the air.

Avoid exposure to stored clothes in boxes or wardrobes for months after removal from storage and wash them before wearing

to avoid the pets