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Asthma and Allergy

This comprehensive overview explores asthma and allergies, focusing on atopy and the mechanisms of IgE-mediated allergic responses. It examines indoor and outdoor allergens, their impact on respiratory health, and the increasing prevalence of asthma and atopy over the last 30 years. The text highlights the importance of allergen identification and avoidance, including practical measures for reducing exposure to common indoor allergens such as dust mites and pet dander. Additionally, it discusses occupational asthma, its diagnostic challenges, and the relevance of inhalation challenges in management.

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Asthma and Allergy

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Presentation Transcript

  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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