Asthma (bronchial asthma) is a condition in which you get recurrent episodes of breathlessness. Most often it starts in children under age 10 years, when it affects many more boys than girls, and many of them will grow out of it. It also often starts between ages 10 years and 30 years, but then equally in both sexes.
The breathlessness is due to difficulty in getting air into the lungs due to 3 factors; constriction of the muscles around the airways (bronchospasm), swelling of the lining of the airways (mucosal oedema) and secretions inside the airways (increased mucus production). Episodes of breathlessness can come on suddenly and are occassionally life threatening. In-between these attacks, at least in the early stages, breathing is completely normal.
Attacks can be set off by allergens (pollen, dust etc), exertion, infection (mainly Upper respiratory infections, Map 405) and emotion (eg having a fright).
There can be family history (genetic factor) and often the person also has eczema, hay fever or an allergy to something else.
Global Burden of Disease estimated in 2002 Asthma caused 2.3% of all male years spent living with a disability worldwide.
Asthma caused 0.42% of all deaths worldwide in 2002, an average of 39 deaths per million people per year.