Transcript Food allergy in children - Asia Pacific Association of

Food allergy in children
Hugo Van Bever
Department of Pediatrics
National University Singapore
APAPARI Workshop, Hanoi, May 2008
Food Allergy…
Fact or Fiction?
1. Difficult problem
group of diseases
2. Lot of non-scientific data … opinions… truths… tradition…
stories.
3. Food
other types of reaction (intolerance,
intoxication, etc…)
4. Too many children are labeled as being “food-allergic”
Adverse reactions to food
 Food intolerance (most common)
 Food allergy (hypersensitivity)
 Food aversion (phobia)
FOOD INTOLERANCE
- toxins
- infections
- pharmacological properties of food
- host factors (lactase deficiency)
Food allergy
= an immunologically-mediated reaction
against food
1. IgE-mediated
Others… (less evidence)
2. Cell-mediated reactions
(T lymphocytes - delayed onset)
3. Mixed types
(atopic dermatitis)
4. Other mechanisms
( unknown - CIC – complement – etc…)
Prevalence of food allergy
1. General population: 2 %
2. Young children (< 3 yrs): 8 %
3. Singapore children: 4 – 5 %
SPECIFIC GROUPS
4. Young children with severe eczema: 90 %
5. Children with asthma: < 10 %
Manifestations of food allergy
1. SKIN: urticaria – angioedema > eczema
2. RESPIRATORY: rhinitis – asthma
3. GI TRACT: diarrhea – vomiting – FTT
- eosinophilic gastroenteritis
- enterocolitis
4. GENERAL: anaphylactic shock
5. OTHER: migraine, hyperactivity,
sleep disturbances etc… ?
Foods triggering anaphylaxis in
Singaporean children (1992 – 1996)
124 children with acute anaphylaxis at NUH
mean age (yrs)
1. Egg and milk
11 %
0.7
2. Bird’s nest
27 %
4.5
3. Chinese herbs
7%
5.0
4. Crustacean seafood 24 %
11.0
5. Others *
30 %
7.0
* Chicken, duck, ham, fruits (banana, rambutan), cereals, gelatin and spices
Goh et al. Allergy 54, 1999, 78-92.
Common culprits - Singapore children
• Infants:
hen's egg
cow’s milk
Common culprits - Singapore children
• Older children
seafood (shellfish), bird’s nest,
Chinese herbs, eggs
FISH
Sweden – 39% of foodallergic children are
allergic to cod
Uncommon in Singapore
- per capita consumption of 25.05kg
Every food has its own story…
cow’s milk
hen’s egg
peanuts, fish, seafood, …
prevalence
age
6 months
3 yrs
5 yrs
Sensitization to food…
sensitization to allergens…
1. prenatal sensitization
2. postnatal sensitization
Sensitization to food…
eating, touching and
smelling…
peanuts
fish
hen’s egg
Allergy to cow’s milk proteins in mother’s
milk or in hydrolyzed cow’s milk infant
formulas assessed by intestinal permeability
measurements.
Barau E et al.
Allergy 1994; 49:295-8.
mother’s milk
ovalbumin
peanut protein
cow’s milk protein
Case
• 9 month old boy
• Totally breastfed
• 1st introduction of CM formula
• One minute after the first “bite”…
Prenatal sensitization to
allergens…does it exist?
1. clinical evidence
(peanuts – ovalbumine – pollen – house
dust mite – cat - dog)
2. allergens in amniotic fluid & cord blood
3. active transport through placenta
Exposure to peanuts in utero and in infancy and the development of
sensitization to peanut allergens in young children.
Frank L, Marian A, Visser M, Weinberg E, Potter PC. Pediatr Allergy
Immunol 1999, 10, 27-32.
… mothers who consumed peanuts more than
once a week during pregnancy were more likely
to have a peanut-allergic child than mothers who
consumed peanuts less than once a week (odds
ratio=3.97, 98% confidence interval 0.73-24).
Allergic sensitization during pregnancy influences the
offspring’s immune reactions. A study in a mouse model
(H. Renz, 1999).
study group
Ovalbumin challenge
(every second day)
decreased INF-g
(x8–9)
control group
PREGNANCY
BIRTH
Direct evidence for transplacental allergen
transfer.
Szépfalusi et al. Pediatr Res 2000, 48, 404-7.
maternal side
BLG
8
Bet v1 10
Human IgG
fetal side
8
2
= increase
= Ig receptor involvement
Diagnosis of food allergy
1. IgE-mediated food allergy
- SPT – IgE
2. Non-IgE-mediated food allergy
- patch test
- in vitro: LTT (cytokine profile?)
research …
GOLDEN STANDARD = DBPCFC
Utility of food-specific IgE concentrations in predicting
symptomatic food allergy. Hugh A. Sampson. JACI
2001, 107, 891.
Diagnostic decision points of 95%
- cow’s milk
- egg
- peanut
- fish
15 kU/L
7 kU/L
14 kU/L
20 kU/L
n = 100, mean age = 3.8 yrs
Future immunomodulatory
therapies for food allergy
1. Humanized monoclonal anti-IgE
2. Mutated allergen protein immunotherapy
3. Peptide immunotherapy
4. Immuno-stimulatory sequences
5. Probiotics (?) no effect on allergic reactions
Alternative feedings in case of CMA
1. Breast milk
2. Soy formulas (?)
3. Goat formulas (?)
4. Hypoallergenic formulas
( partial hydrolysate formulas)
5. Amino acid-based formulas
(complete hydrolysate formulas
Use of hypoallergenic formula in the prevention of
atopic disease among Asian children.
Chan et al. J Paediatr Child Health 2002; 38; 84-8.
(), Hypoallergenic milk group; (---) cow’s milk-based infant formula.
p = 0.093
Primary prevention of atopy: food
allergen avoidance
-- BREAST FEEDING
Saarinen AM, Kajosaari M. Breastfeeding as prophylaxis
against atopic disease: prospective follow-up study until 17
years old. Lancet 1995; 346: 1065 - 1069.
-- HYPO-ALLERGENIC MILK
Vandenplas Y et al. The long-term effect of a partial whey
hydrolysate formula on the prophylaxis of atopic disease.
Eur J Pediatr 1995; 154: 488 - 494.
The long-term effect of a partial whey hydrolysate
formula on the prophylaxis of atopic disease.
Vandenplas et al. Eur J Ped 1995, 154, 488.
prevalence of CMP sensitivity
Conclusion: Food Allergy…
Fact or Fiction?
… A fact… surrounded with lot’s of fiction
… a lot of non-scientific data …
opinions… truths… tradition…
stories … etc …
scientific data
Conclusion…
Still … breast is best
…but… impossible to study
… no contra-indications…