Lecture 12: Infant/Child Allergies Flashcards
1
Q
Allergy definition
A
When a person reacts to a substance in the environment that is harmless to most people
2
Q
What are common allergies?
A
Dust mites, pets, pollen, insects, moulds, medications and foods
3
Q
How many people will develop allergies at some time during their life?
A
1 in 5
4
Q
How many children will develop eczema?
A
1 in 10
5
Q
What percent of children have a food allergy?
A
5-10%
6
Q
What percent of adults have a food allergy?
A
2-4%
7
Q
What is atopic disease?
A
A genetic tendancy to develop allergic disease
8
Q
A child/person with atopy produces elevated…
A
IgE antibodies after exposure to enviornmental allergens
9
Q
What is IgE?
A
A type of immunoglobulin antibody
10
Q
Atopic diseases present with one or more of?
A
- Asthma
- Allergic rhinitis
- Eczema or hives
11
Q
What is allergic rhinitis?
A
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)
12
Q
If someone has one atopic disease…
A
They are more likely to develop one of the other two (or both)
13
Q
What is atopic dermatitis?
A
Inflammation of the skin - reddened, swollen, itchy, weeping skin
14
Q
What is a food allergy?
A
An immune mediated hypersensitivity reaction to a food
15
Q
What are hives (urticaria)?
A
Itchy, raised lumps on the skin, can occur anywhere on the body
16
Q
What is typically the first atopic disease to manifest; usually in early infancy?
A
Eczema
17
Q
What percent of children with eczema have progression to asthma and/or rhinochonjunctivitis?
A
40%
- Most develop respiratory symptoms before 5 years
18
Q
What is progression in atopic disease termed as?
A
The atopic march
19
Q
Approx. what percent of infants with eczema will also have or develop a food allergy?
A
40%
20
Q
Majority of children with asthma develop symptoms by what age?
A
6
21
Q
What is wheezing?
A
Sign of asthma; high-pitched, whistling noise than usually occurs with exhaling
22
Q
Not all children who have wheezing develop asthma AND…
A
Not all children with asthma wheeze
23
Q
What percent of children have at least one wheeze episode before 3y?
A
50%
- BUT only one-third will develop asthma before age 6
24
Q
What are the two types of adverse food reactions?
A
- Immune mediated (primarily food allergy)
- Non-immune mediated (primarily food intolerance)
25
What are the 4 types of immune mediated food reactions?
- IgE mediated
- Non-IgE mediated
- Mixed IgE and non-IgE medicated
- Cell mediated
26
What are IgE mediated reactions?
Most common type of allergic response:
- Involves antibodies (+ve sIgE)
27
How do we test for IgE mediated allergies?
Measure levels of IgE and can be backed up with a skin prick test
28
What are non-IgE Medicated responses?
Immune response - centered usually in the gut, less immediate, do not produce antibodies
29
What are mixed IgE and Non-IgE mediated responses?
A combination expressing a range of symptoms
30
What are cell-mediated responses?
immune reactions that involve T cells (a type of white blood cell) rather than antibodies (e.g. contact dermatitis)
31
What is an IgE mediated food allergy?
An immune mediated hypersensitivity reaction to food
32
How does IgE work to mediate the food response?
The antibodies identify food proteins and signals the immune system to react
33
What are mast cells?
The first line of defence in an IgE mediated food allergy
34
Where are mast cells found?
Skin, lunges, nose, mouth, blood and gut
35
What do mast cells contain?
Histamines which are released and increase blood flow and cause inflammation
36
How many foods are responsible for 90% of all allergic reactions to food?
- Milk
- Eggs
- Fish
- Shellfish
- Treenuts
- Peanuts
- Wheat
- Soybeans
- Sesame
37
What are the common symptoms of a food allergy?
- Swelling, hives, or welts
- Nausea and vomiting
- Becoming pale and floppy
- Difficulty breathing
38
What are the most commonly consumed major food allergens among NZ infants?
- Egg
- Dairy
- Wheat
39
Which food allergies are most likely to be outgrown?
- Cows milk
- Egg
- Wheat
- Soy
40
Which food allergies are most likely to be persistent?
- Peanuts (75% persistent)
- Treenuts (90% persistent)
- Fish, shellfish (80% persistent)
41
10% of people who have a cows milk allergy will also have a...
Soy allergy
42
20% of people who have a wheat allergy will also have a reaction to...
Gluten
43
Food intolerances are...
Non-immune mediated
44
Non-immune mediated responses are less common in...
Infants under 2
45
What are the types of non-immune mediated responses?
- Metabolic (FODMAP)
- Pharmacologic
- Toxic
- Other/Unidentified
46
What are non-immune mediated reactions?
An adverse reaction to a food that does not involve the immune system (do not produce IgE antibodies)
47
What are common non-immune mediated reactions?
Non-protein substances such as:
- CHO
- Chemicals
- Food additives
- Toxins
- Irritants
48
What are common non-immune mediated reaction symptoms?
Can vary and include:
- Diarrhoea
- Nausea
- Cramping
- Headache
48
How long do non-immune mediated reactions take to kick in?
Usually less immediate/delayed up to 20 hours after a food is eaten
49
How are non-immune mediated reactions commonly diagnosed?
Typically elimination and reintroduction
50
What percent of parents reported food allergies?
12.6%
- Over-diagnosed by parents
51
What were the two most common food allergies reported by parents?
Cows milk and secondly egg
52
Why do we not use allergy testing as a screening tool?
Can cause unnecessary exclusion, there is a high prevalence of false positives
53
How do skin prick tests diagnosis allergies?
If weal diameter is greater than 3mm
54
What are examples of serum specific IgE blood tests?
EAST = Enzyme Allergosorbent Test
RAST = Radio-Allergosorbent Test
55
What is the scale for Serum specific IgE blood tests?
0 = Not detected
1 = Low
2 = Low/moderate
3 = Moderate
4 = High
5 = High
5 = Very High
56
What are examples of unorthodox testing methods?
- Hair analysis
- Iridology
- Cytotoxic food testing
- Vega Testing
- Pulse Testing
- Kinesiology
57
What is wrong with unorthodox testing methods?
They have no scientific basis, are unreliable and provide non reproducible results
58
What are the adverse consequences of unorthodox testing methods?
- False positives
- Expensive
- Result in unnecessary dietary avoidance, can lead to malnutriton
59
Why is there a global rise in food allergies? (GHSMD)
- Genetics and environment
- Hygiene hypothesis
- Skin exposure (food based skin products)
- Methods of food processing
- Delayed introduction of allergenic foods
60
What is the hygiene hypothesis?
Proposes that less exposure to infection in early life is associated with an increased change of developing allergies
61
Genetic influence is likely....
Multifactorial with offspring inheriting 'atopy genes'
62
What does it mean that genetic factors have a strong hereditary component?
If both parents are affected by an atopic disease, 40% of offspring will be affected
63
What are environmental factors that influence the rise in food allergies? (MWEH)
- Migration differences (low to high atopy country)
- 'Window of opportunity'
- Exposures
- Hygiene hypothesis
64
What is the critical window of time?
Starts already in utero and ends in school age depending on the kind of exposure
65
What is the dual allergen exposure hypothesis?
suggests that food allergies develop through two distinct pathways: sensitisation occurs when allergens are absorbed through the skin, while tolerance develops when allergens are introduced via the gastrointestinal tract at an early age - early controlled oral exposure to allergens to potentially prevent food allergy is important
66
What does evidence say about maternal exclusion
That there is no protective effect (don't avoid, if anything encourage oral exposure)
67
What do recent studies suggest the presence of might support the induction of tolerance towards solid foods in infants?
Maternal dietary proteins in amniotic fluid, cord blood and human milk
68
Breastfeeding during the period that solid foods are first introduced may help reduce what?
Reduce the risk of the infant developing allergies, although evidence for this is low
69
There is moderate evidence that probiotics during pregnancy and breastfeeding may help prevent what?
Ezcema in early life - controversial
69
Up to 3 serves per week of what may be beneficial during breastfeeding and pregnancy to help prevent eczema in early life?
Oily fish (contains omega 3 fatty acids)
70
Why can recommendations about probiotic supplements not currently be made?
Because the optimal species and dose of probiotics is unclear
71
What does evidence say about partially or fully hydrolyzed formulas for the prevention of eczema, food allergy, asthma or allergic rhinitis?
That there is no evidence to support it
72
If breastfeeding is not possible, what should be given?
A cows milk based formula
73
Cows milk vs. Soy or Goat milk formula for reducing risk of evidence
There is no evidence that soy or goats milk formula reduces the risk of allergies compared with cow's milk formula
74
When should the introduction of solid foods be?
Around 6 months, not before 4 months and preferably whilst breastfeeding
75
When should common food allergens be introduced? (Oral Exposure)
Before 12 months of age
- Including high risk infants
76
How should new common allergens be introduced?
One at a time, around 1 or 2 days apart
77
Once a common allergen food is tolerated...
Continue to give regularly to maintain tolerance
78
Why does smearing food on the skin not help to identify food allergies?
Infants skin is very sensitive and skin irritation does not equate to food allergy
- Smearing on skin of a child with eczema may increase the risk
79
Use skincare products that....
DO NOT contain food protein
80
How should skin be treated for those with eczema?
Apply moisturiser at least twice a day, avoiding those that contain food products
81
How do we diagnose Non-IgE mediated food allergies?
clinical symptoms and will
have negative SPT/serum IgE testing
82
When should oral exposure be done?
From 6 months and before 12 months of age, introduce all allergen foods (e.g. egg, peanut, treenut, milk, soy, wheat, fish, seafood, sesame) into the
infant’s diet, and offer regularly once introduced.
83
Food intolerance is more common in?
Older children and adults
84
What is the most common food intolerances?
lactose and fructose intolerance, other FODMAP foods
85
Food intolerance can be related to reduction in....
Digestive enzymes e.g. lactase
86
Babies reacting to cow’s milk will also react to...
Other mammalian milks i.e. goat and sheep milk
87
Why is lactose free formula not suitable for babies who react to cows milk?
not suitable as baby is reacting to the protein in the milk
88
What age should soy formula not be?
Not for under 6 months
89
What are infant milks for IgE and Non-IgE cows milk protein allergy?
- Extensively hydrolysed formula
- Rice formula
- AA formula
