Is asthma prevalence increasing or decreasing?

There are large variations globally in the prevalence of asthma in children.

Time trends have shown a mixed picture:

- increases in low prevalence centres
- plateau or even a decrease in high prevalence centres

Atopy has less influence on asthma in low and middle income countries. Breast feeding exerts a protective effect only on non-atopic asthma in non-affluent countries.

References:
Recent perspectives on global epidemiology of asthma in childhood. Asher MI. Allergol Immunopathol (Madr). 2010 Jan 25. [Epub ahead of print]
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