Lecture 12: Infant/Child Allergies Flashcards
Allergy definition
When a person reacts to a substance in the environment that is harmless to most people
What are common allergies?
Dust mites, pets, pollen, insects, moulds, medications and foods
How many people will develop allergies at some time during their life?
1 in 5
How many children will develop eczema?
1 in 10
What percent of children have a food allergy?
5-10%
What percent of adults have a food allergy?
2-4%
What is atopic disease?
A genetic tendancy to develop allergic disease
A child/person with atopy produces elevated…
IgE antibodies after exposure to enviornmental allergens
What is IgE?
A type of immunoglobulin antibody
Atopic diseases present with one or more of?
- Asthma
- Allergic rhinitis
- Eczema or hives
What is allergic rhinitis?
Also known as Hay fever, is a type of inflammation in the nose which occurs when the immune system overreacts to allergens in the air
- conjunctivitis (nose/eyes)
If someone has one atopic disease…
They are more likely to develop one of the other two (or both)
What is atopic dermatitis?
Inflammation of the skin - reddened, swollen, itchy, weeping skin
What is a food allergy?
An immune mediated hypersensitivity reaction to a food
What are hives (urticaria)?
Itchy, raised lumps on the skin, can occur anywhere on the body
What is typically the first atopic disease to manifest; usually in early infancy?
Eczema
What percent of children with eczema have progression to asthma and/or rhinochonjunctivitis?
40%
- Most develop respiratory symptoms before 5 years
What is progression in atopic disease termed as?
The atopic march
Approx. what percent of infants with eczema will also have or develop a food allergy?
40%
Majority of children with asthma develop symptoms by what age?
6
What is wheezing?
Sign of asthma; high-pitched, whistling noise than usually occurs with exhaling
Not all children who have wheezing develop asthma AND…
Not all children with asthma wheeze
What percent of children have at least one wheeze episode before 3y?
50%
- BUT only one-third will develop asthma before age 6
What are the two types of adverse food reactions?
- Immune mediated (primarily food allergy)
- Non-immune mediated (primarily food intolerance)
What are the 4 types of immune mediated food reactions?
- IgE mediated
- Non-IgE mediated
- Mixed IgE and non-IgE medicated
- Cell mediated
What are IgE mediated reactions?
Most common type of allergic response:
- Involves antibodies (+ve sIgE)
How do we test for IgE mediated allergies?
Measure levels of IgE and can be backed up with a skin prick test
What are non-IgE Medicated responses?
Immune response - centered usually in the gut, less immediate, do not produce antibodies
What are mixed IgE and Non-IgE mediated responses?
A combination expressing a range of symptoms
What are cell-mediated responses?
immune reactions that involve T cells (a type of white blood cell) rather than antibodies (e.g. contact dermatitis)
What is an IgE mediated food allergy?
An immune mediated hypersensitivity reaction to food
How does IgE work to mediate the food response?
The antibodies identify food proteins and signals the immune system to react
What are mast cells?
The first line of defence in an IgE mediated food allergy
Where are mast cells found?
Skin, lunges, nose, mouth, blood and gut
What do mast cells contain?
Histamines which are released and increase blood flow and cause inflammation
How many foods are responsible for 90% of all allergic reactions to food?
- Milk
- Eggs
- Fish
- Shellfish
- Treenuts
- Peanuts
- Wheat
- Soybeans
- Sesame