Eosinophils are white blood cells known as phagocytes. Their presence is not normal because they do not develop unless the body is fighting an infection or an allergic reaction of some kind. Complete blood count tests do, however, offer a numerical range for a healthy level of eosinophils. Numbers outside of the healthy range represent elevated levels that are indicative of dangerous disease.
"Singular" eosinophils refers to a blood content percentage of eosinophils ranging from 0 to 8 per cent. According to Lymphomation.org, levels from 1 to 8 per cent represent a healthy response to allergic inflammatories in the form of histamines in the bloodstream. Mayo Clinic (mayoclinic.com) staff explain, however, that an allergic reaction in a localised tissue area does not necessarily prompt the release of histamines in the bloodstream. Favourable eosinophil blood test results do not mean that high levels of the phagocytes are not at a site of infection or inflammation.
Eosinophil percentages in the bloodstream over 8 per cent are considered high. High levels are referred to clinically as eosinophilia. Eosinophilia indicates a body's persistent fight against the presence of a destructive foreign body like a parasite, toxin or fungus. High levels also generally mean that the white blood cells are fighting inflammation. According to the Mayo Clinic's Dr. Joseph Butterfield, each eosinophil detected on a blood test represents at least 200 eosinophils in body tissue. Due to the potential for severe organ and tissue damage, elevated eosinophils that persist for longer than six months warrant treatment.
Doctors examine patients with eosinophilia for a number of underlying causes. Once a cause is found, it is treated with the hopes of possibly preventing further damage. Some conditions and diseases attributable to eosinophila include eosinophilic leukaemia, chronic myelogenous leukaemia, various parasitic infections, atopic dermatitis, hay fever, scarlet fever, helicobactor pylori stomach ulcers, ovarian cancer, trichinosis, Hodgkins lymphoma, Crohn's disease, ulcerative colitis, idiopathic hypereosinophilic syndrome, drug allergies, asthma, ascariasis, lupus and other disorders of the immune system.
Cincinnati's Children's Hospital Medical Center identifies seven primary organs where increased eosinophils are likely to be found. Muscular, rheumatic-related disease such as Churg-Strauss syndrome is sometimes an attribute. Skin disorders that cause eosinophilia include urticaria, Well's syndrome, Shulman's syndrome and Kimura's disease. Conditions of the heart such as aortic stenosis and septal defects are often secondary to hypereosinophilic syndrome. Sometimes eosinophils are trying to fight toxins in the lungs that cause pleurisy or bronchopulmonary aspergillosis. Central nervous system dysfunctions, various gastrointestinal diseases and kidney infections may also be culprits.