Definition
Eosinophilia (e-o-sin-o-FILL-e-uh) is the presence of too many eosinophils in the body. An eosinophil is part of a group of cells called white blood cells. They are measured as part of a blood test called a complete blood count. This is also called a CBC. This condition often signals the presence of parasites, allergies or cancer.
If eosinophil levels are high in the blood, it is called blood eosinophilia. If the levels are high in inflamed tissues, it is called tissue eosinophilia.
Sometimes, tissue eosinophilia may be found using a biopsy. If you have tissue eosinophilia, the level of eosinophils in your blood is not always high.
Blood eosinophilia can be found with a blood test such as a complete blood count. Over 500 eosinophils per microliter of blood is thought to be eosinophilia in adults. Over 1,500 is thought to be hypereosinophilia if the count remains high for many months.
Causes
Eosinophils play two roles in your immune system:
Destroy foreign substances. Eosinophils consume matter flagged by your immune system as harmful. For example, they fight matter from parasites.
Control infection. Eosinophils swarm an inflamed site when needed. This is important to fight disease. But too much can cause more discomfort or even tissue damage. For example, these cells play a key role in the symptoms of asthma and allergies, such as hay fever. Other immune system issues can lead to chronic inflammation as well.
Eosinophilia happens when eosinophils swarm a site in the body. Or when the bone marrow makes too many. This can happen due to many reasons including:
Parasitic and fungal diseases
Allergic reactions
Adrenal conditions
Skin disorders
Toxins
Autoimmune disorders
Endocrine conditions.
Tumors
Certain diseases and conditions that can cause blood or tissue eosinophilia include:
Acute myelogenous leukemia (AML)
Allergies
Ascariasis (a roundworm infection)
Asthma — a long-term condition that affects airways in the lungs.
Atopic dermatitis (eczema)
Cancer
Churg-Strauss syndrome
Crohn’s disease
Drug allergy
Eosinophilic esophagitis
Eosinophilic leukemia
Hay fever (allergic rhinitis)
Hodgkin lymphoma (Hodgkin disease)
Hypereosinophilic syndrome
Idiopathic hypereosinophilic syndrome (HES), an extremely high eosinophil count of unknown origin
Lymphatic filariasis (a parasitic infection)
Ovarian cancer
Parasitic infection
Primary immunodeficiency
Trichinosis (a roundworm infection)
Ulcerative colitis (a type of inflammatory bowel disease)
Parasites and allergies to medicines are common causes of eosinophilia. Hypereosinophilia can cause organ damage. This is called hypereosinophilic syndrome. The cause for this syndrome is often unknown. But it can result from some types of cancer such as bone marrow or lymph node cancer.
