Asthma and AllergyAsthma and Allergy
Atopy v AllergyAtopy v Allergy
AsthmaAsthma
• Aeroallergens – indoor & outdoorAeroallergens – indoor & outdoor
Occupational allergensOccupational allergens
AtopyAtopy
The propensity to produce IgE to The propensity to produce IgE to allergensallergens
Demonstrated using Skin prick tests Demonstrated using Skin prick tests to common inhalant allergensto common inhalant allergens
AllergyAllergy
IgE mediated inflammatory tissue IgE mediated inflammatory tissue damage in response to an allergen damage in response to an allergen causing clinical diseasecausing clinical disease
Asthma - epidemiologyAsthma - epidemiology
X 2- 3 increase last 30 yearsX 2- 3 increase last 30 years
Concomitant similar increase in Concomitant similar increase in atopy, hayfever and eczemaatopy, hayfever and eczema
? Environmental Change? Environmental Change
? Less infections ( hygiene ? Less infections ( hygiene hypothesis )hypothesis )
AllergensAllergens
OutdoorOutdoor
Pollens-Pollens-– TreeTree– Grass Grass
Moulds- Moulds- – AlternariaAlternaria– AspergillusAspergillus– CladosporiumCladosporium– PenicilliumPenicillium
Inhalation of allergenInhalation of allergen Immediate response ( IgE mediated )Immediate response ( IgE mediated )
– Max: 20 min.Max: 20 min.– Ends : 60 min.Ends : 60 min.
Late response in 50% (Eosinophil )Late response in 50% (Eosinophil )– Onset 3hOnset 3h– Max 12 hMax 12 h– End 24 hEnd 24 h
Responsible for airways hyperreactivityResponsible for airways hyperreactivity
Allergen ID and avoidance therefore very importantAllergen ID and avoidance therefore very important
Allergic history and negative skin Allergic history and negative skin teststests
Remember grass pollen allergyRemember grass pollen allergy
PollenosisPollenosis Prof. Paul Potter, Cape TownProf. Paul Potter, Cape Town
Big role for grass pollens in respiratory allergyBig role for grass pollens in respiratory allergy
Kikuyu grassKikuyu grass
Bermuda grassBermuda grass
Buffalo grass ( l’herbe bourrique )Buffalo grass ( l’herbe bourrique )
SPT regents to detect allergy to these being developedSPT regents to detect allergy to these being developed
Mauritus has all of these grasses in abundanceMauritus has all of these grasses in abundance
Indoor allergens-avoidanceIndoor allergens-avoidance
House dust mite allergenHouse dust mite allergen– LargeLarge
– Not easily air-borneNot easily air-borne
– Needs close proximity to bedding to be Needs close proximity to bedding to be inhaledinhaled
House dust mite avoidanceHouse dust mite avoidance
Mite impermeable mattress coversMite impermeable mattress covers
Hot wash bedding linen ( 55 C )Hot wash bedding linen ( 55 C )
Remove moquettesRemove moquettes
Light curtainsLight curtains
Vacuum clean with high filtration cleanerVacuum clean with high filtration cleaner
Pet allergensPet allergens
Remove the petRemove the pet
Clean itClean it
Remove carpets ( x 100 fold antigen)Remove carpets ( x 100 fold antigen)
Asthma- none of usual Asthma- none of usual aeroallergensaeroallergens
Think of occupational asthmaThink of occupational asthma
Occupational AsthmaOccupational Asthma
Asthma Asthma initiatedinitiated by an agent inhaled by an agent inhaled at workat work
Cf. Work-related asthmaCf. Work-related asthma– Pre-existingPre-existing asthma provoked by an asthma provoked by an
irritant in the workplaceirritant in the workplace
Occupational asthmaOccupational asthma
– Only a % of workers affectedOnly a % of workers affected
– Latent period before onset ( 2 Yr.)Latent period before onset ( 2 Yr.)
– Improvement during periods away from Improvement during periods away from workwork
– Once established can be triggered by Once established can be triggered by really small doses of antigenreally small doses of antigen
Usual suspectsUsual suspects HMWHMW ( Biologic ) ( Biologic )
– LatexLatex
– Flour ( 334 )Flour ( 334 )
– Laboratory mammals(188) Laboratory mammals(188)
– Bacillus subtilisBacillus subtilis
LMW LMW ( haptens )( haptens )– Colophony ( 175 )Colophony ( 175 )
– Wood dustWood dust
– Diisocyanates ( 658 )Diisocyanates ( 658 )
– Platinum saltsPlatinum salts
– Acid anhydrides ( 364 )Acid anhydrides ( 364 )
– GlutaraldehydeGlutaraldehyde
– Plastics workersPlastics workers
– Bone cementBone cement
Occupational asthmaOccupational asthma
Diagnosis will have major impact on Diagnosis will have major impact on patient’s lifepatient’s life
False + ve : needless loss of jobFalse + ve : needless loss of job
False – ve : Needless continuing False – ve : Needless continuing exposureexposure
Be carefulBe careful