PATHCHAT Edition No. 31
Please contact your local Ampath pathologist for more information.
Author: Dr. Cathy van Rooyen, MBChB, MMed Path, FRC (Pathology)
Allergy, Immunology, and Virology Pathologist
Introduction
🔹 Allergic rhinitis and inhalant allergies are common conditions seen in primary care.
- Misdiagnosis and suboptimal management can lead to:
- Poor quality of life.
- Uncontrolled asthma and frequent exacerbations.
- Increased healthcare costs.
- A rational and cost-effective approach to inhalant allergy screening is essential.
✅ A structured diagnostic approach improves patient outcomes by:
- Identifying sensitizing allergens.
- Guiding allergen avoidance strategies.
- Selecting patients for allergen immunotherapy.
Recognizing a History Suggestive of Inhalant Allergy
🔹 Key Symptoms Indicating Inhalant Allergy:
- Frequent sneezing, nasal congestion, and postnasal drip.
- Seasonal or perennial symptoms (e.g., worse in spring or with dust exposure).
- Asthma exacerbations linked to specific triggers.
- Eye irritation (itching, watering, redness).
- Recurrent sinus infections due to chronic allergic inflammation.
✅ Screening for inhalant allergy is recommended for symptomatic patients using:
- Phadiatop® inhalant screen (detects atopy but not specific allergens).
- Panel of inhalant skin prick tests or specific IgE blood tests.
📌 Phadiatop® is an atopy screening test, not an allergen mix. It detects broad allergenic responses and cross-reactivity but does not specify individual allergens.
Stepwise Approach to Inhalant Allergy Diagnosis
🔹 Step 1: Perform a Phadiatop® Inhalant Screen
✅ A positive Phadiatop® test confirms atopy but does not identify specific allergens.
✅ If positive, further testing is required to determine the offending allergen.
🔹 Step 2: Follow-Up Testing for Specific Inhalant Allergens
✅ According to South African guidelines, the following inhalant allergens should be tested:
- Bermuda grass pollen.
- Rye grass pollen.
- House dust mites (Dermatophygoides pteronyssinus and Blomia tropicalis).
- Moulds (Alternaria alternata, Cladosporium herbarum, Aspergillus fumigatus).
- Pet allergens (cat and dog dander).
🔹 Step 3: Consider Seasonal and Regional Factors
✅ For patients with seasonal exacerbations (e.g., springtime allergies), additional testing for tree pollen IgE should be done:
- Use a tree mix screen or test for specific tree pollen allergens in the patient’s environment.
✅ Adjust testing based on the patient’s geographic location:
- Western Cape & Eastern Cape: Add Epicoccum mould spores and German cockroach IgE.
- KwaZulu-Natal: Add Oriental cockroach IgE.
- Central & Northern South Africa: Add maize pollen, weed pollen mix (cosmos and khakibush), and Eucalyptus tree pollen IgE.
📌 Testing should be tailored to the patient's history and environmental exposure.
South African Inhalant Allergy Panel (SAARWG Panel)
🔹 The SAARWG (South African Rhinitis Working Group) recommends testing the following nine allergens:
✅ Grass Pollens:
- Bermuda grass.
- Rye grass.
✅ Moulds:
- Alternaria alternata.
- Cladosporium herbarum.
- Aspergillus fumigatus.
✅ House Dust Mites:
- Blomia tropicalis.
- Dermatophygoides pteronyssinus.
✅ Pet Allergens:
- Cat dander.
- Dog dander.
Ampath’s Role in Inhalant Allergy Testing
✅ Ampath supports the South African inhalant allergy testing guidelines.
✅ Offers comprehensive testing, including Phadiatop® and specific IgE panels.
✅ Consulting pathologists are available to assist with result interpretation and patient management.
Key Takeaways for Clinicians
✅ A positive Phadiatop® test confirms atopy but does not specify the allergen—follow-up testing is necessary.
✅ Testing should be guided by symptom history, seasonal triggers, and regional allergen exposure.
✅ The SAARWG panel recommends testing for grass pollens, moulds, house dust mites, and pet allergens.
✅ Ampath provides expert consulting services for interpreting inhalant allergy test results.