Immunological Diseases / immunological diseases
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Immunological
diseases occur when the immune system, which normally protects against
infections, malfunctions. The most common types of immunological
diseases are allergies, autoimmune diseases, and immune deficiencies.
An allergy is an abnormal reaction of the immune system to foreign
substances, such as plant pollen, fungal spores, animal danders,
medications, and foods. Rhus dermatitis is an allergy caused by
contact with urushiol, an oil resin produced by poison ivy, poison
oak, and poison sumac.
Autoimmune diseases develop when the immune system goes awry and
attacks the body's own tissues. Autoimmune disorders includes lupus
erythematosus, rheumatoid arthritis, juvenile-onset diabetes, and
myasthenia gravis. The causes are unknown, although some scientists
suspect the diseases may be triggered in some cases by a pathogen,
such as a virus, or other environmental factor.
Immune deficiency diseases develop when the immune system becomes
impaired, resulting in more common, frequent, or severe infections.
The immune system may be damaged by a genetic abnormality or by
illness, injury, the use of a strong drug such as those used in
chemotherapy, or malnutrition.
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