Serial Histoplasma Complement Fixation
Definition Serial histoplasma complement fixation is a test for antibodies to the fungus Histoplasma by a serologic technique called complement fixation. This test is usually repeated about 4 weeks later. If a patient has an active infection, the antibodies should increase over that time period. This is called a "rise in the titer of paired serologies".
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Why is the Test Performed?
The test is performed to detect fungal infection caused by Histoplasma. A repeated test may show an increase in the titer, which would suggest an active rather than a prior infection.
Serology refers to the study of serum for its antibody content. An antibody defends the body against bacteria, viruses, fungus, or other foreign bodies (antigens). Certain microbial cells stimulate the body to produce these antibodies during active infection. Antibody production increases during the course of infection. In the initial stage of an illness, little antibody may be detected. For this reason, serology tests are often repeated 2 to 4 weeks after the initial sample.
In the laboratory, the antibodies react with antigens in specific ways that can be used to confirm the identity of a specific microorganism. There are several serology techniques that can be used depending on the suspected antibodies. Serology techniques include agglutination, precipitation, complement-fixation, fluorescent antibodies, and others.
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