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Allergy overview

Allergy overview. Allergy and atopy. Response to foreign substances need immune system Immune response is normal in healthy people Immune system response is exaggerated in allergic patients which lead to damage body tissues. Allergy overview. Allergy and atopy

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Allergy overview

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  1. Allergy overview Allergy and atopy • Response to foreign substances need immune system • Immune response is normal in healthy people • Immune system response is exaggerated in allergic patients which lead to damage body tissues

  2. Allergy overview Allergy and atopy Exaggerated immune response in allergic patients produce ↑ IgEs (type 1 hypersensitivity)

  3. Allergy overview • Allergy and atopy • Atopy is the tendency to develop an exaggerated IgE response, as reflected by +ve SPT to one or more common allergens (i.e. a predisposition to develop allergic disease) • Allergy is the clinical expressionof atopy (i.e. the symptoms). Symptoms depend on the target organ. For example, allergy affecting the lungs causes allergic asthma, allergy affecting the nose causes AR

  4. Allergy overview Allergy and atopy • Many people are atopics but don’t have allergic symptoms • Atopics may or may not develop allergic symptoms later

  5. Allergy overview Allergy and atopy • We don’t know how atopics become allergics • If we know it will be easy to interrupt this process to avoid atopics to develop allergy – but we don’t

  6. Allergy overview Types of allergy Allergic manifestations are several according to the system involved like: • asthma • rhinitis • atopic dermatitis (eczema) • acute Urticaria – Angioedema • food allergy • anaphylaxis

  7. Allergy overview Types of allergy – asthma - 4 cardinal symptoms • Cough • chest tightness • wheeze • breathlessness

  8. Allergy overview Types of allergy – rhinitis • sneezing, runny and itchy nose • seasonal (hay fever) • perennial (all the year) • often together with allergic conjunctivitis (red itchy watery eyes)

  9. Allergy overview Types of allergy – AD (eczema) • allergy in skin • itching + redness + scaling, weeping and thickening of the skin • anywhere but more in face, scalp, flexures of (elbows, knees and wrists)

  10. Allergy overview Types of allergy – Acute urticaria • allergy in skin • skin redness and itch followed by hives (red swollen area) • hives initially red then pale

  11. Allergy overview Types of allergy – Acute urticaria • this reaction is called "nettle rash" as it resemble a nettle sting • Angioedema is form of urticaria that manifests as swelling • of face and mouth

  12. Allergy overview Types of allergy – food allergy • GIT → diarrhea, nausea, vomiting • out side GIT → Urticaria, eczema, asthma and anaphylaxis

  13. Allergy overview Types of allergy – anaphylaxis • Sudden, sever, generalized allergic reaction • Itching, angioedema, bronchospasm, sever drop in BP with vascular collapse and shock

  14. Allergy overview Allergens Wide spectrum of allergens

  15. Allergy overview Allergens • airborne (aeroallergens) • contact allergens • ingested allergens

  16. Allergy overview Allergens – HDM • tiny, spider-like (its not insect) • live on flakes of: • human skin • house dust • fungal spores • pollen grains • plant fibers and insect scales

  17. Allergy overview Allergens – HDM • invisible to naked eye • People become allergic to its protein in their droppings

  18. Allergy overview Allergens – HDM • All houses are infested • Highest concentration in: • mattress • pillows

  19. Allergy overview Allergens - HDM People are exposed to high levels because: • most of them spend most of their time indoor (poor ventilation) • many hours in bed

  20. Allergy overview Allergens – pollen • small size pollens distributed by wind to great distances • So…….symptoms can be caused by local exposure or even great distance away

  21. Allergy overview Allergens – pollen • grass (timothy grass, ryegrass) • tree (birch, hazel, London plan) • weed pollen (mugwort)

  22. Allergy overview Allergens – pets Allergen exposure either • airborne allergy • contact allergy

  23. Allergy overview Allergens – cats • commonest cause of pet allergy • allergens mostly found in saliva → so allergen reach fur during grooming and licking → when dry can shed to air for hours or days

  24. Allergy overview Allergens – dogs • cause allergy in similar way • dog allergy less common than cats

  25. Allergy overview Allergens – moulds • aspergillus fumigatus, cladosporium and alternaria alternata • less common cause of allergy • types: - indoor moulds in damp house - outdoor moulds

  26. Allergy overview Allergens – true food allergy • Rare • milk, wheat, egg, peanut and shellfish

  27. Allergy overview • Epidemiology of allergic diseases • Epidemiology: the study of the occurrence, distribution and causes of diseases • Prevalence: number of cases present at a given time per 1000 or 100000 of population • Incidence: number of new cases occurring within a defined time period (eg. A year) per 1000 or 100000 of the population

  28. Allergy overview Epidemiology – prevalence • 15 – 20 % in UK • More in younger people • >50 y the prevalence is lower

  29. Allergy overview Epidemiology – prevalence Hayfever prevalence is - 16% in 15 – 24 years - then decline after this age (Wuthrich 1998, LAIA 1998)

  30. Allergy overview Epidemiology – prevalence Prevalence of allergic diseases is increasing (asthma, eczema, hayfever)

  31. Allergy overview Epidemiology – prevalence of atopy • Prevalence of atopy is increasing • there is increasing prevalence of sIgE to common aeroallergens in children (in 2 studies in Switzerland and Japan) • Increase +ve SPT in adults living in London in 1974 compared with those in 1988 (sibbald et al 1990)

  32. Allergy overview Epidemiology – prevalence of hayfever Four-fold increase number of summer consultations (seasonal) between 1950 - 1980

  33. Allergy overview Epidemiology – prevalence of asthma Prevalence is increasing about 70% from 1974 to 1986 (Lewis et al 1996)

  34. Allergy overview Epidemiology – prevalence of eczema Substantial increase in reporting mothers that their child (5 -7 years) had eczema since 1964 (Taylor et al 1984)

  35. Allergy overview Epidemiology – prevalence of allergic contact dermatitis Prevalence constantly changes as the allergen come and go

  36. Allergy overview Epidemiology – prevalence of food allergy • Prevalence difficult to determine because of population misbelieve • 20 % of population think they have food allergy BUT <2% of adults have it

  37. Allergy overview Epidemiology – prevalence of food allergy Increased prevalence of peanut prevalence in UK • 1,2 % had +ve SPT to food at 4 years (Tariq et al 1996) • Sampson 1997 • 44% of children with moderate to sever atopic dermatitis have +ve SPT to peanut between 1981 to 1985 • but in 1994 increases to 68%

  38. Allergy overview Epidemiology – prevalence of anaphylaxis • At 1940s it was mainly to penicillin • Recently its mainly to latex (gloves) in medical procedures (Dillard and McCollum 1992)

  39. Allergy overview Risk factors • FH of allergy or atopy - if one parent has allergy there is 25 – 30% chance the child will have - if both parents have allergies chance increase to 50 – 80% • smoking - maternal smoking during pregnancy - paternal smoking during childhood

  40. Allergy overview Risk factors • lifestyle (diet, socioeconomic status and housing environment) - lower prevalence in eastern than western countries in adults (Jogi et al 1998) - lower prevalence of asthma and atopy in children in east Germany compared to west Germany (Braback et al 1994, Nowak et al 1996)

  41. Allergy overview Risk factors • age and environmental factors - <3years → childhood asthma -later in childhood → other atopic disorders

  42. Allergy overview Risk factors – factors which decrease risk • Being breastfed for at least 16 weeks • Some infections

  43. Allergy overview Mortality Inspite allergy isn’t fatal disease but mortality still present: • 1600 die from asthma each year in UK • anaphylaxis, urticaria, angioedema can be fatal (very rare) - death due to penicillin anaphylaxis only 1/7.5 million injections (Idose et al 1968) - venom anaphylaxis 1/6.5 million stings (Parrish 1965) - 4 death's/year due to peanut

  44. Allergy overview Mortality Improvement in population awareness of anaphylaxis and its management is necessary

  45. Allergy overview • Morbidity • Allergies cause • considerable suffering • and medical treatment costs

  46. Allergy overview Morbidity – rhinitis We think its trivial problem but it causes considerable morbidity

  47. Allergy overview Morbidity – rhinitis • widespread morbidity • reduced work productivity • lost school days

  48. Allergy overview Morbidity – rhinitis • significant effect on life quality • Fatigue • - headache • - impaired thought process • - discomfort from itchy, watery eyes and nose

  49. Allergy overview Morbidity – rhinitis 5. sedating antihistamines (Vuuman et al 1993, O'Hanlon and Ramaekers 1995) - affect mental performance - car accidents - accidents at work - ↓ work productivity - impaired school performance

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