Blocking Antibodies References 4. Identification of the Causative Allergen by measurement of Allergen Specific IgE S pecific allergy testing should be guided by the history, clinical examination, environmental assessment of the patient and an assessment of atopy. Specific allergy tests are classified into in vivo and in vitro tests. In Vivo Tests Index Skin Prick Tests S kin tests are reliable, easy to perform, give rapid results and are cost effective. They can be performed by any practitioner trained in the technique and in the interpretation of results.
Skin tests are generally reliable for the identification of aero-allergens.
For the diagnosis of food allergy they are more useful for their negative predictive value with currently available stored food extracts. Their sensitivity increases for food allergy if fresh extracts are used. They may result in severe local and rarely even anaphylactic reactions and should therefore always be conducted in a facility where emergency and resuscitation facilities are available. S kin tests are commercially available in South Africa only from Bayer. The standard skin test kit has 8 aero-allergens plus a positive and negative control.