discussion will concentrate mostly on the allergic, early-onset type.
Early-onset asthma has the following characteristics:
- it starts during early childhood
- it appears to run in families
- it is often associated with eczema from birth
- individuals who suffer from this type of asthma have whealing skin reactions to
common allergens - they also have antibodies in their serum which could be transferred to the skin of
nonsensitized people to cause the same whealing skin reactions.
Individuals who suffer from allergic asthma with the above characteristics are called "atopic"
and they have levels of IgE immunoglobulins up to six times higher than those found in patients
suffering from non-atopic asthma. Atopic individuals have a hereditary predisposition to
anaphylactic (or Type-I) reactions.
Many different allergens are implicated but the main ones are faecal particles of house-dust
mites, pollen, fungal spores, feathers, animal dander and cats' saliva. Once the mast cells have
been primed by exposure to these allergens and high levels of IgE immunoglobulins adhere to
them, they also become hypersensitive to other non-specific allergens such as smoke, tobacco
smoke, petrol fumes, dust, atmospheric pollutants, perfumes, etc. Occasionally an allergic
reaction in the bronchi can be elicited by ingested allergens from food such as shellfish, fish,
eggs, milk, yeast or wheat which reach the bronchi via the bloodstream.
It should be noted here that asthma that starts during early childhood is not necessarily atopic
asthma. In other words, an early onset is not the only criterion for defining asthma as "allergic"
or "atopic". The familial incidence, its connection with eczema and the typical whealing skin
reactions on inhalation of allergens are other important features necessary to diagnose atopic
asthma.
There are cases of asthma starting in early childhood without an allergic basis. This happens
especially when a small child suffers from an upper respiratory infection (invasion of Wind-Cold
or Wind-Heat) which is either not treated properly or treated with antibiotics. If Wind is not
expelled properly, it lodges itself in the Lungs and impairs the dispersing and descending of
Lung-Qi resulting in breathlessness and Phlegm. On the other hand, the presence of Wind and
Phlegm in the Lungs predisposes the child to further invasions of external Wind which make the
situation worse. Thus, a vicious cycle sets in when the child is progressively weakened and
prone to invasions of external Wind and the breathlessness gets gradually worse. This chapter,
however, will concentrate primarily on discussing the typical allergic asthma, as non-allergic
asthma can be diagnosed and treated mostly according to the guidelines given for "Wheezing"