Asthma is one of the world’s most common lung diseases and affects about one 1 in every 13 people in our country. It is estimated that more than 25 million people are affected by this disease. It can affect anyone without any discrimination of age or gender. In asthma, airways to the lungs get inflamed and thickened. These airways are consequently obstructed by mucous and fluid, resulting in spasms in the bronchial tubes. Breathing becomes difficult. People who are extremely sensitive and have allergies invariably have asthma. The severity of asthma varies from one person to another. Treatment depends on the type of asthma they are affected by.  

Eosinophils are white blood cells in the blood that fight diseases.

They are part of the immune system that helps fight infections However, if there is an increased presence of eosinophils in the blood, it results in inflammation of the airways. This will affect the sinus passages, nasal passages, and the lower airways. Patients are likely to have frequent attacks of sinus-related diseases. Higher the number of eosinophils in the blood, the person is likely to have frequent and severe asthma attacks. Eosinophilic asthma is one type of asthma that affects people when they are adults but it can also occur in children. In adults, this can result in a severe attack. 

What causes severe eosinophilic asthma?

No specific cause has been established yet for severe eosinophilic asthma. Doctors are yet to establish if it can be triggered by food or exercise. This is more common in adults between the ages of 35 and 50 and men and women are at equal risk. When the body is fighting a parasitic infection, the immune system produces more eosinophil cells. Research is being conducted to see if this can result in severe eosinophilic asthma. Asthma sometimes runs in the family, although no scientific proof has been established yet, to see if severe eosinophilic asthma is a hereditary condition. 

Asthma vs. severe eosinophilic asthma
Regular asthma invariably affects a person during childhood. It could be triggered by many allergens – pollen, pets, dust, chemicals or strong fragrances. Asthma causes the airways to swell, resulting in wheezing or difficulty in breathing. It responds well to corticosteroids in the form of inhalers. 

Eosinophilic asthma affects a person during adulthood. A person who is affected need not be allergic or sensitive. Inflammation occurs throughout the respiratory tract. A person experiences shortness of breath when they are having an asthma attack. Corticosteroids are not as effective as a medication for this type of asthma. This is a rare subtype of asthma and affects adults more than children.

Symptoms of severe eosinophilic asthma
A person affected by severe eosinophilic asthma experiences:

• Shortness of breath
• Bouts of coughing
• Wheezing
• Difficulty in breathing
• Chronic rhinosinusitis 
• Inflammation in the nasal and mucous membrane
• Nasal congestion
• Loss of smell
• Tightness in the chest
• Runny nose
• Watery eyes
• Airflow obstruction because of inflamed lungs

The patient could feel one or more of the symptoms simultaneously. The symptoms are usually persistent and severe and require medical intervention.

Diagnosis of severe eosinophilic asthma
There is more than one way to diagnose severe eosinophilic asthma:

Blood test
After a basic physical examination, evaluation of the symptoms and current medication, doctors will recommend a simple blood test to diagnose severe eosinophilic asthma.  A normal reading should show less than 500 eosinophils per microliter of blood. If the tests show higher levels, it indicates elevated levels. However, a blood test is not conclusive proof that eosinophils are present in the lungs.

Sputum test
Since a blood test cannot be conclusive proof, a sputum test is considered a more reliable test. The patient has to cough up sputum which is tested under a microscope. If the tests show an eosinophils count of more than 3%, the doctor will diagnose that the person has severe eosinophilic asthma. If the patient is not able to cough up sputum, the doctors will nebulize them with water and salt to produce some sputum samples for the test.

Bronchial biopsy
This test is used only for someone who has severe symptoms and is already being treated for asthma.  Doctors choose this invasive procedure only when they want to make sure that the person is not suffering from any other airway disease. This test is done under mild sedation, where a scope is inserted through the nose or the mouth. The tissues from the airway are collected and tested for eosinophils. If the biopsy confirms their presence despite treatment using steroids, then the patient is diagnosed with severe eosinophilic asthma.

Along with these tests, a doctor would recommend imaging tests like CT scan and additional tests to check the functioning of the lungs. There are other diseases of the lungs and respiratory tract which show similar symptoms. The doctors will plan further treatment based on the above tests and how patients respond to the treatment.