The eosinophil is a type of white blood cell. Eosinophils are produced in the bone marrow and are normally found in the bloodstream and the gut lining. They contain proteins that help the body to fight infection from parasitic organisms such as worms. But in certain diseases these proteins can damage the body. The term eosinophilia refers to conditions in which abnormally high amounts of eosinophils are found in either the blood or in body tissues.
Eosinophilia occurs in a wide range of conditions.
Its commonest causes in the UK are allergic diseases such as asthma and hay fever , while worldwide the main cause is parasitic infection. It can also occur in relation to common skin diseases, drug reactions, and parasitic infections. Some tumours, e.g. lymphoma. Other rarer skin diseases, e.g. dermatitis herpetiformis. Unknown causes, labelled hypereosinophilic syndrome.