Food and Respiratory Allergy in Zimbabwe
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Food and Respiratory Allergy in Zimbabwe Professor Elopy Sibanda Asthma Allergy and Immune Dysfunction Clinic Zimbabwe [email protected] Introduction • There is a world wide increase in allergic diseases. • First wave was that of inhaled allergies and these were documented by the series of ISAAC studies. Small studies in Zimbabwe were concurrent. – Kambarami et al. 1999; Sibanda, 1999; Westritschnig et al., 2003 • Second wave is emerging and being recognized in Europe, North America and Asia Boyce et al, 2010; Wandg and Simpson • Evidence from Africa is limited. • This presentation will draw from the experiences of the Asthma Allergy and Immune Dysfunction Clinic, a private sector clinic in Harare Zimbabwe. Background • Few studies of food and respiratory allergy in Africa • Limitations are a result of limited numbers of specialists and interested physicians – No academic departments of allergy in many countries. • The absence of allergy reports does not reflect the absence of disease. This report • Report focuses on patients whose symptoms were severe enough to warrant referral to a specialist. • Data do not represent a population survey. Patients • 981 patients • Born between 1920 and 2013 • Presented for diagnosis and management of suspected allergic diseases • Report audits the allergic diagnoses entertained Clinical Conditions at Presentation • Allergic rhinitis • Asthma • Allergic conjunctivitis • Atopic dermatitis • Urticaria/angioedema • Suspected food allergies (gluten, etc.) Immunological basis of allergy • Diseases of the immune system respect the immunological sequence of events. • Allergic symptoms are preceded by the elaboration of immune responses to an allergen source. No allergen, no allergic disease! • The key intervention in allergology is: 1. to identify and 2. to avoid the triggering allergen source. That ameliorates the symptoms. • This presentation reports on the allergen sources associated with food and respiratory allergy. Diagnostic methods • Clinical history • Careful physical examination • Skin prick testing • Serological assays of serum samples – Results presented exclusively from immunoblot analyses of test sera. There was broad concordance with SPT. General Findings • Multiple sensitization is common • Food and inhalant allergen source co- sensitization frequent • Sensitization patterns are not diagnostic of clinical entity • Careful anamnesis and examination crucial Respiratory Allergens 45 40 35 30 25 20 15 10 5 0 cat dog horse D. pter. mugwort Alternaria D. farinae tree pollen aspergillus grass pollen cladosporium 45 40 35 30 25 20 15 Asthmatics 10 All allergy 5 0 80 70 60 50 40 Pollen D. pter. 30 D. farinae Expon. (D. pter.) 20 Expon. (D. farinae) 10 Expon. (D. farinae) 0 MW Austria Zimbabwe rDer p1 26 96% 80% rDer p2 10.7 15% 45% rDer p7 23.7 0% 35% rDer p10 36 10% 55% Sensitization to house dust mite molecules. There are significant differences in allergenic molecules. Some of the differences in molecular sensitization explain pathological changes Srinita Banerjee, Yvonne Resch, Kuan-Wei Chen, Ines Swoboda, Margit Focke-Tejkl, Katharina Blatt, Natalija Novak, Marianne van Hage, Magnus Wickman, Adriano Mari, Ashok Purohit, Gabrielle Pauli, Elopy N Sibanda, Portia Ndlovu, Wayne Thomas, Vladislav Krzyzanek, Ursula Malkus, Peter Valent, Rudolf Valenta, Susanne Vrtala Der p 11 is a major allergen for house dust mite allergic patients suffering from atopic dermatitis Manuscript Accepted, July 2014: Journal of Investigative Dermatology Respiratory Allergy HDM MOST FREQUENT ALL MORE COMMON IN YOUNGER AGE GROUPS ASSOCIATED WITH RHINITIS, ASTHMA, CONJUNCTIVITIS 60 D. pter 50 40 30 20 10 40 grass pollen 35 0 30 tree pollen 0-9 20-29 40-49 60-69 25 years years yars years 20 15 10 5 0 Alternaria -5 aspergillus 40-49 yars cladosporium 30-39 years 0-9 years 40-49 yars 20-29 years 10-19 years 20-29 years 30-39 years 50-59 years 60-69 years 10-19 years 0-9 years 0 10 20 40 35 30 y = -2.97x + 36.29 25 R² = 0.3032 grass pollen 20 tree pollen 15 mugwort Linear (grass pollen) 10 5 0 40-49 30-39 20-29 10-19 0-9 years yars years years years (n=116) (n=35) (n=45) (n=48) (n=98) Correlations ECZEMA Food Allergy Bilateral impact! • Flexural Dermatitis Dermatitis % of all food allergen sensitised (N=981) kiwi shrimp celery apple potato carrot almond hazelnut peanut soya rice rye flour wheat flour milk codfish egg yolk egg white 0 5 10 15 20 Food Allergen sensitization Most Common: • Potato (16%) • Peanut (15%) • Food grains • Soya 9%, rice 9%, wheat 7%) • Egg • (egg white more than yolk) • Fruits and vegetable • Milk 45 40 35 30 25 20 15 Peanut (%) 10 Potato (%) 5 Log. (Peanut (%)) 0 Log. (Potato (%)) 1920-1939 (n=5) 1960-1969 (N=73) 1960-1969 1940-1949 (N=14) 1950-1959 (N=26) 1970-1979 (N=82) 1980-1989 (N=91) 1990-1999 (N=143) 2000-2009 (N=162) Peanut Sensitization • Demonstrated by SPT, RAST • Associated with anaphylaxis in Europe – confirmed sensitization to components rAra h 2, rAra h 1, rAra h 3, nAra h 6 and rAra h 9. – Levels of IgE antibodies to Ara h 1, Ara h 2. – Peanut sensitisation is often associated with severe reactions and anaphylaxis in Europe • No severe reactions, no known case of anaphylaxis in association with peanut sensitization within Zimbabwe – unexplained peanut tolerance in this population Potato • Most common food allergen source tested. • No identifiable adverse events associated • Tested as part of panel • Clinical significance to be ascertained. Cross-reactivity Pollen-Food • Well recognized for birch and ragweed • Bermuda grass is the major allergen source in Zimbabwe. Cross-reactivity with food items has not been studied in Zimbabwe Summary Respiratory Allergy • Respiratory disease due to allergy (asthma, rhinitis, AC) are increasing • House dust mites (D.pter., D. farinae), grass pollen are the most common triggers The allergenic molecules recognized by patients are different from those seen in Europe. Research needed Environment and allergy Locally relevant allergen extracts Summary Food Allergies Food allergies are common • Severity ranges from mild to life threatening • There is evidence of increase • In contrast to Europe, some of the most frequent (peanut/potato) are not associated with severe symptoms Research needed • to understand the environmental factors responsible • To learn protective vis-à-vis aggravating factors • Characterise regionally relevant dietary components. Thank you.