Nature of allergens
Allergens are substances that evoke allergy symptoms. Allergen usually consists of proteins often with enzyme properties. The allergens cause the production of a type of antibody, called IgE (refers to Immunoglobulin E), that is specifically associated with the development of allergy. Almost any protein substance may act as an allergen but in the tropics the following are highly allergenic: house dust mites and their fecal pellets, pet dander (usually cats and dogs) and common foods (egg, milk, peanuts or other nuts, wheat, soy bean, fish, prawns, crabs, garlic, bird nest soup and bananas). In some cases of rhinoconjunctivitis in Malaysia, in addition to dust mite allergens, other allergens such as, pet dander, oil palm pollens, Acacia tree pollens, grass pollens or pigeon droppings may be partly responsible for the clinical symptoms. A detailed clinical history will often reveal the suspected causal allergens responsible for the allergy. However, appropriate tests need to be performed to definitely identify the causal allergens before avoidance measures are taken.