It happens very often that a child who is allergic to dust or dander, starts sneezing or wheezing and then progresses to get a full-fledged upper or lower Respiratory tract infection, complete with fever and other associated morbidity.
Allergies and infections go together, the former often being responsible for setting the stage for the latter.
Asthma can either be allergic or non-allergic. In allergic asthma, an allergic reaction to inhaled irritant pollen, pet dander and dust mites triggers an attack. The immune system coils into action, but instead of helping, it causes inflammation.
Respiratory allergies can be diagnosed by X-Ray chest, observation and auscultation through stethoscope in the chest. There will be congestion with wheezing sound heard in the chest while examining through stethoscope. In children, six years and older, pulmonary function tests can be useful.