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- Allergy or Non-allergic hypersensitivity?
- Profile of Allergy
- Nature of Allergens
- Risk factors of Allergy
- Symptoms of Allergy
- Immune process in Allergy
- Maternal factors in Allergy
- Allergy tests
- Diagnostic procedures for food Allergy
- Food Allergy in infants and children
- Food Allergy in adults
- House dust mite Allergy
- Rhinitis
- Eye Allergy (Conjunctivitis)
- Asthma
- Urticaria/ Hives
- Atopic Dermatitis/ Eczema
- Contact Dermatitis
- Anaphylaxis
- Allergen Immunotherapy
- Effect of Probiotics in Allergy
- Sick Building Syndrome
- Air pollution and Allergy
- Unproven Allergy tests
- Nutritional Supplements in Allergy
- Allergy in Autistic children
Risk factors of allergy
Allergic diseases have a complex origin. In general the interaction between two main factors, specifically genetic factors that modulate the immune system and environmental factors such as allergens, play a critical role in the development of allergic disorders. Family history is a common feature of allergy. Children of families with allergy symptoms have a high risk for the development of allergies during infancy and childhood. However, in a small group allergies may be present in individuals in the absence of parental history of allergy or asthma.
Since the immune system is involved in the development of allergies the disease tends to last a long time unless special measures are taken to down-regulate or modulate the immune response. Intake of allergenic foods early in life before 6 months of age may trigger allergy in high risk genetically predisposed babies. Frequent exposure to pollution chemicals and tobacco smoke combined with high exposure to aeroallergen load, such as house dust mites, in early life can promotes the development of respiratory allergies. Allergic diseases are becoming more common because of life style changes associated with industrial development.
Several factors appear to cause the increased risk for allergy. We can control certain risk factors through direct intervention and reduce the chances of allergy development in early life. However, we have no control over genetic factors which we inherit from our parents. Thus, genetically predisposed individuals should be vigilant against exposure to highly allergenic compounds throughout life. The risk factors for allergic diseases include:
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Strong family history of allergic disease (allergy in both parents or one parent plus one sibling is high risk for the newborn baby)
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Elevated levels of cord blood or neonate IgE levels (Elevated IgE levels is a high risk factor for the newborn baby)
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Maternal allergy (it carries four times higher risk for the newborn compared to paternal allergy)
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Breast-milk is best. Introduction of cow's milk or soy milk formula feeds before six months of age should be avoided. However, partially-hydrolyzed hypoallergenic milk formula (e.g. NAN HA 1 for infants less than 6 months and NAN HA 2 for infants older than 6 months) which can also be used as supplement to breast milk is the preferred option for mothers who cannot breast feed
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Introduction of solid foods before 4 to 6 months of age increases the risk for allergy
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Exposure as a child or infant to high levels of house dust mite allergens increases risk for eczema and respiratory allergy
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Early-in-life exposure to furry indoor pets (e.g. cat or dog) increases risk for respiratory allergy
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Passive exposure to cigarette smoke prenatally, neonatally and during childhood increases the risk for respiratory allergy and asthma
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Exposure to environmental pollution as a child or infant (e.g. high levels of car exhaust fumes or fumes from gas heaters) increases the risk for allergy
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Neonatal exposure to oral antibiotics increases the risk of allergy in infancy