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Also called “e-asthma,” eosinophilic asthma is a subtype of asthma. It is associated with very high levels of a type of white blood cell called eosinophils. These white blood cells release pro-inflammatory substances in the body and are a normal part of the immune response to infections and other harmful invaders. Eosinophils are higher in people who have asthma, but occur in much higher levels in people who have e-asthma.
Like other forms of asthma, e-asthma causes persistent inflammation in the airways that can make it difficult—sometimes very difficult—for a person to breathe. Coughing, wheezing and tightness in the chest are all common asthma symptoms. However, eosinophilic asthma has a few characteristics that set it apart from non-eosinophilic asthma.
Age of onset
Though e-asthma can affect people of all ages, it is more common for people who develop asthma as adults to have e-asthma.
Severity
Symptoms of e-asthma are often severe and poorly controlled. Asthma is classified as intermittent, mild, moderate or severe based on the type of treatment needed to get symptoms under control. With severe asthma, a patient will require treatment, such as multiple control medications (typically high-dose corticosteroids, either inhaled or taken as an oral medication) and a rescue inhaler—though symptoms can persist even with these treatments. Studies have found that asthma patients with high levels of eosinophils are also at greater risk for fatal and near-fatal asthma attacks.
Allergies
The most common form of asthma is allergic asthma, where inflammation is triggered by exposure to certain allergens, such as dust mites, pet dander or pollen. Most people with e-asthma do not have a history of allergies.
AERD
Though most people with e-asthma do not have a history of allergies, there is believed to be an association between aspirin-exacerbated respiratory disease (AERD) and e-asthma. AERD is an intolerance to aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs). When a person with AERD ingests aspirin or another NSAID, it can trigger respiratory symptoms including congestion, sinus pain, coughing, wheezing and chest tightness. Some people with AERD also experience skin symptoms and gastrointestinal symptoms, and also experience symptoms after consuming alcohol.
Asthma and severe asthma are more prevalent in people with AERD, and people with AERD often have elevated levels of eosinophils in their blood—though not all people with e-asthma have AERD, and AERD is also associated with other respiratory conditions as well, including chronic sinusitis and nasal polyps.
Treatment
As mentioned above, some patients with severe asthma (whether it is e-asthma or another form of severe asthma) are unable to get symptoms under control, despite treatment with high-dose corticosteroids. Biologic therapies (also called immunomodulators) are another treatment option for severe asthma. These treatments work by targeting the immune processes in the body that contribute to airway inflammation. There are types of biologic therapies that treat eosinophilic asthma and types that treat non-eosinophilic asthma.
