Immunodeficiency or immune deficiency is a state in which the immune system is devoid of the ability to fight infectious diseases. Defects in the immune system that one is born with are referred to as primary immunodeficiencies; whereas cases of immunodeficiency that are acquired are called secondary.
Acquired immunodeficiency is more common than primary immunodeficiency. A person who has an immunodeficiency of any kind is said to be immunocompromised. An immunocompromised person may be particularly vulnerable to infections.
Primary immunodeficiencies involve a number of hereditary, autosomal recessive or X linked disorders. There are over 80 recognised primary immunodeficiency syndromes. The treatment of primary immunodeficiencies depends on the nature of the defect and may involve antibody infusions, long-term antibiotics and even stem cell transplantation. On the other hand, acquired immunodeficiency is a consequence of specific external processes or diseases. Common causes for secondary immunodeficiency are malnutrition, aging and particular medications. Many specific diseases such as cancer directly or indirectly impair the immune system. Immunodeficiency is also the hallmark of acquired immunodeficiency syndrome or AIDS caused by human immunodeficiency virus or HIV, which indirectly attacks the immune system.
The lack of one or more components of the immune system results in immunodeficiency disorders. These can be inherited, acquired through infection or other illness, or produced as an inadvertent side effect of certain drug treatments. Advanced cancer patients may experience immune deficiencies as a result of the disease process or from extensive anticancer therapy. Common viral infections such as influenza, infectious mononucleosis and measles can lead to transient immune deficiencies. Immune responsiveness can also be depressed by blood transfusions, surgery malnutrition and stress. Sometimes, newborns are seen to have defects in their immune systems. Defects in the B cell components lead to the lack of production of antibodies arousing a condition known as agammaglobulinemias or hypogammaglobulinemias, which renders children vulnerable to infectious organisms. Injections of immunoglobulins are the only cure for such disorders. On the other hand, there are children with missing, small or abnormal thymus that lack T cells. The resultant disorders are treated with thymic transplants. There is also a unique medical condition wherein infants are born lacking all the major immune defenses. This is known as severe combined immunodeficiency disease (SCID). Some children with SCID live for years in germ-free rooms and ‘bubbles’. A few SCID patients have also been successfully treated with bone marrow transplants.
The immunodeficiency disorder that tops the list in its severity of damage to the body is AIDS. This syndrome was first recognized in 1981. Its causal virus, HIV destroys T4 cells. AIDS is characterized by a variety of unusual infections and otherwise rare cancers. The AIDS virus also damages tissue of the brain and spinal cord, producing progressive dementia. AIDS is a contagious disease, spread by intimate sexual contact, by direct inoculation of the virus into the bloodstream or from mother to child during pregnancy. Most of the AIDS cases in the United States have been found among homosexual and bisexual men with multiple sex partners, and among intravenous drug abusers. There is presently no cure for AIDS, although the antiviral agent zidovuzine (AZT) appears to hold the virus in check, but only for some time.
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