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Chronic Asthma
In chronic asthma, inflammation can be accompanied by irreparable airflow
limitation. In pre-school children underlying pathology may not exhibit considerable
bronchial hyper reactivity, and there is also no evidence chronic inflammation
is a basis for the episodic wheezing which is associated with viral infections.
Characteristic Features of Chronic Asthma
Theseinclude an alteration of the construction
and functions of elements of the airways. Together, these structural changes
interact with the inflammatory cells and mediators to cause the characteristic
features of the disease.
Asthma occurs in both males and females of all ages, racial groups, and socio-economic levels. It is also found Asthma is usually more common in poor built-up neighbourhoods, and in cold climates, and developed countries, but this is probably due to the poor living conditions of the asthmatic sufferers.
Research suggests genetic factors can also increase the risk of developing
asthma, and children with a family history of asthma are more likely to
develop the disease than other children. However many people with no family
history of asthma can also develop the disorder.
In many countries the frequency of asthma is increasing, particularly in the second decade of life where it affects 10-15% of the population. There is also a noted geographical variation, with asthma being common in more urbanized countries.
Some of the highest rates of Asthma are countries such as New Zealand and Australia, but it is much rarer in Far Eastern countries such as China, Malaysia, Africa and Central and Eastern Europe.
Having said that however long-term follow-up in these developing countries suggests asthma problems may become more frequent as the population becomes more 'westernized'.
Studies of occupational asthma suggest a high proportion of the workforce, perhaps up to 20%, may become asthmatic if exposed to potent sensitizers.
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