Asthma is a chronic disease in which the airways in the lungs become inflamed. The inflammation causes swelling and increases the tendency of the airways to tighten in response to irritants or other triggers. The airways become narrower, causing difficulty breathing and symptoms such as wheezing, coughing and chest tightness. Airway inflammation can be caused by allergens, such as those from dust mites, mold and cockroaches; viral infections; and air pollution, such as diesel exhaust and environmental tobacco smoke.
NIAID-supported research has enhanced understanding of the factors that contribute to asthma severity. Studies have shown that reducing allergens in the home can lessen asthma symptoms (for more information, see Managing Asthma Symptoms). Results from the Asthma Phenotypes in the Inner City (APIC) study, reported in 2016, pinpointed sensitivity to multiple allergens, poor lung function, allergic rhinitis and exposure to second-hand smoke as major factors associated with asthma severity in children.
Other NIAID-supported research has shown that bacterial and viral infections are linked to asthma symptoms. In 2014, researchers at the University of Wisconsin–Madison reported that combined viral and bacterial infections are associated with the increase in asthma symptoms that many children experience during the fall. The same researchers in 2015 identified a cellular receptor for rhinovirus C—a cold-causing virus that is strongly associated with severe asthma attacks—pointing to a novel target for the development of prevention and treatment strategies against rhinovirus C-induced colds and asthma attacks.