![]() ![]() The specificity of the western blot is 97.8%, which means that more than 2% of the tests are false positive. If only some antibodies are present that do not meet the criteria of the positive test, the test result is marked as indeterminate.Ī positive Western blot in combination with a positive ELISA test already means the almost certain presence of HIV, the patient is HIV positive and treatment can start. The presence of certain groups of antibodies is always evaluated. Western blot detects the presence of antibodies against virus proteins: core-proteins (p17, p24, p55), polymerases (p31, p51, p66) a envelope-proteins (gp41, gp120, gp160). It is advantageous to perform tests with samples taken by the same method and evaluated in the same laboratory. If the results of both tests are different (positive and negative), it is tested again. If the second ELISA test is positive again, further testing (western blot) is performed for a high probability of infection. The causes are the same as for a false-negative test, and false-positive results can also be obtained with intravenous drug use, vaccination ( hepatitis, rabies,…) or HIV vaccination as part of the research. If the test is positive, the ELISA is repeated because, of course, the test may be false-positive. The ELISA may also be false negative in cases of autoimmune disease, renal failure, hemodialysis, cystic fibrosis, multiple pregnancies or transfusions, and liver disease. The diagnostic window can last up to 12 weeks (depending on the ELISA type). Although the infection is present in the body, detectable amounts of antibodies have not yet begun to form. However, there may be situations where the patient has recently become infected, resulting in a window period. If the test is negative, there is no reason to suspect HIV infection and the patient is considered healthy. Therefore, the ELISA is used in most cases as the first test in case of suspected HIV infection. The specificity and sensitivity of this test is more than 99%. ELISA is one of the methods for detecting the patient's production of antibodies to the virus. The basis of testing for the presence of HIV in the body is the detection of antibodies in serum or other body fluids. In case of problems with the diagnosis or with the patient, a whole range of other tests is prepared to help confirm or refute the HIV infection. The basis is an ELISA (Enzyme-linked Immunosorbent Assay) test supplemented by western blot. Standard aids diagnosis Ī single multi-test algorithm is used to diagnose human immunodeficiency virus (HIV) infection causing acquired immune deficiency syndrome (AIDS). ![]()
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