Download 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
Exaggerated immune response in allergic patients
produce ↑ IgEs (type 1 hypersensitivity)
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 expression of 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
Allergy overview
Allergy and atopy
• Many people are atopics but don’t have allergic
symptoms
• Atopics may or may not develop allergic symptoms later
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
Allergy overview
Types of allergy
Allergic manifestations are several according to the system
involved like:
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asthma
rhinitis
atopic dermatitis (eczema)
acute Urticaria – Angioedema
food allergy
anaphylaxis
Allergy overview
Types of allergy – asthma - 4 cardinal symptoms
• Cough
• chest tightness
• wheeze
• breathlessness
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)
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)
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
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
Allergy overview
Types of allergy – food allergy
• GIT → diarrhea, nausea, vomiting
• out side GIT → Urticaria, eczema, asthma and
anaphylaxis
Allergy overview
Types of allergy – anaphylaxis
• Sudden, sever, generalized allergic reaction
• Itching, angioedema, bronchospasm, sever drop in BP
with vascular collapse and shock
Allergy overview
Allergens
Wide spectrum of allergens
Allergy overview
Allergens
1. airborne (aeroallergens)
2. contact allergens
3. ingested allergens
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
Allergy overview
Allergens – HDM
• invisible to naked eye
• People become allergic to its protein in their droppings
Allergy overview
Allergens – HDM
• All houses are infested
• Highest concentration in:
1. mattress
2. pillows
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
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
Allergy overview
Allergens – pollen
• grass (timothy grass, ryegrass)
• tree (birch, hazel, London plan)
• weed pollen (mugwort)
Allergy overview
Allergens – pets
Allergen exposure either
• airborne allergy
• contact allergy
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
Allergy overview
Allergens – dogs
• cause allergy in similar way
• dog allergy less common than cats
Allergy overview
Allergens – moulds
• aspergillus fumigatus, cladosporium and alternaria
alternata
• less common cause of allergy
• types:
- indoor moulds in damp house
- outdoor moulds
Allergy overview
Allergens – true food allergy
• Rare
• milk, wheat, egg, peanut and shellfish
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
Allergy overview
Epidemiology – prevalence
• 15 – 20 % in UK
• More in younger people
• >50 y the prevalence is lower
Allergy overview
Epidemiology – prevalence
Hayfever prevalence is
- 16% in 15 – 24 years
- then decline after this age (Wuthrich 1998, LAIA
1998)
Allergy overview
Epidemiology – prevalence
Prevalence of allergic diseases is increasing (asthma,
eczema, hayfever)
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)
Allergy overview
Epidemiology – prevalence of hayfever
Four-fold increase number of summer consultations
(seasonal) between 1950 - 1980
Allergy overview
Epidemiology – prevalence of asthma
Prevalence is increasing about 70% from 1974 to 1986
(Lewis et al 1996)
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)
Allergy overview
Epidemiology – prevalence of allergic contact dermatitis
Prevalence constantly changes as the allergen come and go
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
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%
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)
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
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)
Allergy overview
Risk factors
• age and environmental factors
- <3years → childhood asthma
-later in childhood → other atopic disorders
Allergy overview
Risk factors – factors which decrease risk
• Being breastfed for at least 16 weeks
• Some infections
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
Allergy overview
Mortality
Improvement in population awareness of anaphylaxis and its
management is necessary
Allergy overview
Morbidity
Allergies cause
• considerable suffering
• and medical treatment costs
Allergy overview
Morbidity – rhinitis
We think its trivial problem but it causes considerable
morbidity
Allergy overview
Morbidity – rhinitis
1. widespread morbidity
2. reduced work productivity
3. lost school days
Allergy overview
Morbidity – rhinitis
4. significant effect on life quality
- Fatigue
- headache
- impaired thought process
- discomfort from itchy, watery eyes and nose
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
Allergy overview
Morbidity – asthma in children
• many hospital admissions
• absence from school (NAC 2000)
Allergy overview
Morbidity – asthma
• in elderly more likely to report poor general health,
depression, limitation of daily activities (Enright et al
1999)
• physical and emotional distress
• occupational asthma → change job
• affect career, sport enjoyment, sexual relations
Allergy overview
Morbidity – eczema
• particular problem in children
• 90% before 5years
• Considerable distress due to (itching, soreness)
• Constant scratching leave skin open to infection
Allergy overview
Morbidity – acute urticaria
• Nettle rash cover large areas
• In sever reactions → dramatic drop in BP, loos
consciousness
Allergy overview
Morbidity – acute urticaria
Physical urticaria lead to sever limitation in lifestyle like:
• Prevent them leaving house on hot or cold days
• swimming in cold water
• bathing in hot water
• wearing tight cloth
Allergy overview
Morbidity – chronic Urticaria
Cause mostly unknown
Allergy overview
Morbidity – food allergy
• serious life restriction because its difficult to identify
which food contain the trigger
• full food components (list) usually not clear in many
places (ex: restaurants, take away shops)
Allergy overview
Morbidity – food allergy
Peanut allergy
• small amount can cause anaphylaxis
• this cause life distress
Allergy overview
Gap in provision of allergy care in UK
• inspite large numbers of cases the service is very little
• allergy isn’t part of any undergraduate curriculum in
medical schools
• limited postgraduate opportunity
Allergy overview
Gap in provision of allergy care in UK
• few specialist allergy clinics
• mostly in south east (Respiratory alliance 2003)
• referrals and waiting lists to these centers vary
(3month – 2 years)
• one allergist/2.1 million while one chest physician/100,000
Allergy overview
Gap in provision of allergy care in UK
• allergy treated according to organ most affected inspite
allergics suffer from more than one system
- children with sever rhinitis usually associated with
wheezing
- children with eczema may suffer asthma or anaphylaxis to
peanut
Allergy overview
Gap in provision of allergy care in UK
charities must fill the gap:
• British allergy foundation
• NAC
• Anaphylaxis campaign
• National eczema society
Allergy overview
Gap in provision of allergy care in UK
• These charities provide helplines and information for
allergy sufferers
• Unfortunately there is "alternative practice" with no
evidence tests (ex: analysis from hair sample) by
unqualified people with high prices
Allergy overview
Gap in provision of allergy care in UK
• NHS developed guidelines, setting out the standards of
allergy care (RCP et al 1995)
Allergy overview
Gap in provision of allergy care in UK
Contents of this guideline:
- It shows which conditions need allergy care
- allergic child should be under pediatrician care because
progression in this age is different from adults
- the pre-requisites of allergy clinics in hospitals
Allergy overview
Improving standards of patient care in UK
• BSACI distribute one specialist allergy clinic for
each region
• Each clinic have:
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2 full time allergists
full time specialist nurse
half-time dietician with interest in allergy
one full time specialist registrar in allergy
Allergy overview
Improving standards of patient care in UK
• improving the allergy practice in primary care
• using modern management approaches which can
control most types
• giving more time for (patients assessment, full history,
education, FU)
• training health professionals
Allergy overview
Improving standards of patient care in UK
• SPT is under-used because of:
- many health professionals think its time consuming
-historical reasons of decline of immunotherapy
-perceived lack of need for accurate allergy diagnosis
Allergy overview
Improving standards of patient care in UK
• Medications care:
- how to use (inhalers, nasal spray)
- written notes
• setting up allergy clinics
- by expanding existing asthma clinic
- or open new allergy clinic
Allergy overview
Improving standards of patient care in UK
• appreciate regional considerations like increase of occupational
allergy in certain region because of the presence of factory in
that area
Allergy overview
Gap in provision of allergy care in Saudi
?
• Allergists have to do something to cover this gap!!!
• Tell now there is no Saudi allergy society??!
• One of the most important missions of AAG is to try to
cover this gap
Allergy overview
Saudi allergy and clinical immunology society (SACIS)
Is it
Possible
??