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Asthma and Allergy

Asthma and Allergy. Atopy v Allergy Asthma Aeroallergens – indoor & outdoor Occupational allergens. Atopy. The propensity to produce IgE to allergens Demonstrated using Skin prick tests to common inhalant allergens. Allergen-Antibody interaction. Prick Test Reagents. Skin Prick Tests.

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Asthma and Allergy

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  1. Asthma and Allergy • Atopy v Allergy • Asthma • Aeroallergens – indoor & outdoor • Occupational allergens

  2. Atopy • The propensity to produce IgE to allergens • Demonstrated using Skin prick tests to common inhalant allergens

  3. Allergen-Antibody interaction

  4. Prick Test Reagents

  5. Skin Prick Tests

  6. Allergy • IgE mediated inflammatory tissue damage in response to an allergen causing clinical disease

  7. Asthma - epidemiology • X 2- 3 increase last 30 years • Concomitant similar increase in atopy, hayfever and eczema • ? Environmental Change • ? Less infections ( hygiene hypothesis )

  8. Allergens • Outdoor • Pollens- • Tree • Grass • Moulds- • Alternaria • Aspergillus • Cladosporium • Penicillium

  9. Allergens • Indoor • Cat • Dog • Cockroach • Birds

  10. Inhalation of allergen • Immediate response ( IgE mediated ) • Max: 20 min. • Ends : 60 min. • Late response in 50% (Eosinophil ) • Onset 3h • Max 12 h • End 24 h • Responsible for airways hyperreactivity • Allergen ID and avoidance therefore very important

  11. Pollenosis and BHR

  12. Allergic history and negative skin tests • Remember grass pollen allergy

  13. Pollenosis • Prof. Paul Potter, Cape Town • Big role for grass pollens in respiratory allergy • Kikuyu grass • Bermuda grass • Buffalo grass ( l’herbe bourrique ) • SPT regents to detect allergy to these being developed • Mauritus has all of these grasses in abundance

  14. Why study pollens • Potential for immunotherapy

  15. Indoor allergens-avoidance • House dust mite allergen • Large • Not easily air-borne • Needs close proximity to bedding to be inhaled

  16. House dust mite avoidance • Mite impermeable mattress covers • Hot wash bedding linen ( 55 C ) • Remove moquettes • Light curtains • Vacuum clean with high filtration cleaner

  17. Mattress Covers

  18. Vacuum cleaners

  19. Pet allergens • Remove the pet • Clean it • Remove carpets ( x 100 fold antigen)

  20. Cat Eviction

  21. Asthma- none of usual aeroallergens Think of occupational asthma

  22. Occupational Asthma • Asthma initiatedby an agent inhaled at work • Cf. Work-related asthma • Pre-existing asthma provoked by an irritant in the workplace

  23. Occupational asthma • Only a % of workers affected • Latent period before onset ( 2 Yr.) • Improvement during periods away from work • Once established can be triggered by really small doses of antigen

  24. HMW ( Biologic ) Latex Flour ( 334 ) Laboratory mammals(188) Bacillus subtilis LMW ( haptens ) Colophony ( 175 ) Wood dust Diisocyanates ( 658 ) Platinum salts Acid anhydrides ( 364 ) Glutaraldehyde Plastics workers Bone cement Usual suspects

  25. Occupational Asthma

  26. Serial Peak Flow- latex

  27. Bronchial Provocation Testing

  28. Inhalation Challenge

  29. Inhalation Challenge

  30. Occupational Asthma

  31. Occupational asthma • Diagnosis will have major impact on patient’s life • False + ve : needless loss of job • False – ve : Needless continuing exposure • Be careful

  32. Thank You • Discussion

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