Asthma follows no set course. It can appear, disappear and reappear with no discernible pattern, and it is not specific to any age or gender.
Asthma is prevalent throughout the world, although in some people or countries it is virtually nonexistent (asthmatics are rare among Alaskan Eskimos and North American Indians, for instance). The potential role of genetic and environmental factors in activating asthma cannot be ignored.
Asthma seems to run in families. Hereditary factors predispose some people to asthma. It is quite common to find a close relative of an asthmatic also suffering from an allergic condition such as asthma, hayfever or eczema. What baffles doctors is that some asthmatics have no history of asthma in their families, while other people with a number of asthma sufferers in their families develop no symptoms.
Asthma attacks can occur when a susceptible person is exposed to certain environmental triggers. Environmental irritants are many, but not all irritants affect all asthmatics in the same way.
Doctors are often asked by patients if moving from their present environment will help their asthma. Generally this is not advised. A move may well result in a merely temporary respite from asthma symptoms. It has also been found that symptoms commonly recur after a time. In Australia asthma appears to be evenly spread occurring at about the same frequency in both urban and rural areas. A move to another environment may be well justified in an extreme case of asthma, but generally very few asthma sufferers experience a complete remission after a change of environment.