The ELISA medical test, also known as an enzyme-linked immunosorbent assay, measures antibodies in the blood. These proteins are a sign that the immune system is battling against various diseases and infections. While most ELISAs give positive or negative results, some tests also measure a hormone's level. This article outlines the process and the benefits of ELISA testing. You can also use this test to rule out certain medical conditions and diagnose yourself.
The ELISA medical test is a highly accurate and sensitive way to determine the presence of a specific antigen. It is often used for disease diagnosis and quality control testing and is also useful for rapid presumptive screening. The ELISA test can also be used to determine the presence of a potential food allergen or coeliac disease. In many cases, a positive result can be used to determine a person's risk for developing that disease.
Today, ELISA has become a standard in clinical medical testing. The ELISA uses antibodies to detect proteins, and the vast majority of clinical laboratories use it. ELISA is used to detect a large variety of diseases and allergies. For example, it can identify a number of viruses and allergies including HIV, West Nile, and SARS-CoV-2 coronavirus. Moreover, ELISA has also been used to detect COVID-19 coronavirus.
An ELISA medical test may produce false positives or false negatives. False positives are when the test results are falsely positive or negative for a specific disease. For example, an ELISA for HIV can indicate a patient has the disease when the actual infection is HIV. A positive result may require a follow-up test such as a Western blot. The ELISA test may also detect a condition that is not HIV-related.
In some settings, a quantitative ELISA medical test may be desired. However, a full standard curve occupies valuable wells on a plate, which reduces the overall test's sensitivity. While this trade-off may seem unavoidable, the results of ELISA tests are rarely 100 percent accurate. False positive results can also occur, which is why sensitivity and specificity are important in the development of ELISA tests.
The ELISA medical test is usually performed by a laboratory. A blood sample will be collected. A healthcare provider will clean the arm with antiseptic solution. Then, the arm will be wrapped in a tourniquet that will create pressure on the veins. A needle will then be inserted into a vein to draw blood. Once enough blood is collected, the needle will be removed and a small bandage will be placed on the arm where the needle was inserted. After detection, they will also clean the ELISA plate by using a plate washer to clean the residues on the plate, which is helpful to avoid mistakes.
Most ELISAs are based on experimental antibodies. Monoclonal antibodies are the cornerstone of most ELISA tests. They offer high specificity but are more expensive than polyclonal antibodies. Polyclonal antibodies bind to multiple binding sites, increasing sensitivity and improving specificity. Although polyclonal antibodies increase sensitivity, they increase the assay time and add more steps. However, if you can tolerate the procedure, it may be worth your while.
A recent study showed that ELISA is a highly sensitive and specific assay for malaria. Its sensitivity ranged from 76 to 100% for P. vivax samples. However, because the test used anti-human IgM conjugates and parasitic crude antigens, it was associated with a high rate of false-positive results. However, it was still useful for detecting malaria in blood samples from people who had not been exposed to the disease.
The ELISA method involves the binding of anti-Plasmodium antibodies to a panel of recombinant parasite antigens. The antigens in the ELISA test are made from cultured Plasmodium falciparum, recombinant P. vivax antigens, and merozoite surface proteins. The cutoff value is determined by multiplying the optical density of the negative control wells by four.
Until recently, the IFAT was considered the gold standard of malarial serology and was the only validated assay used in blood banks. However, IFAT is not automated, and the readings may be affected by technicians. It also requires the use of a fluorescent microscope. Moreover, there is no standardization of the IFAT reagents, which makes it difficult to use the test routinely in blood transfusion centers.
DiaMed ELISA malaria antibody test was more sensitive than IFAT for P. vivax infection and showed a better efficiency index than the IFAT. This method, however, has several limitations, such as poor sensitivity and limited sensitivity for malaria. Besides, it missed some cases of acute infection. The high variability of Plasmodium blood-stage antigens in human blood could explain this phenomenon.
The sensitivity of the assay was also evaluated. The sensitivity was evaluated by comparing serum samples from known malaria and Toxoplasma-infected individuals. In the absence of positive results, the test is considered negative, but the result is not conclusive enough to prove that the donor is free of malaria. In some cases, antibodies against the parasite may not be detectable during the first few days of malaria transmission, making it an important tool for rapid diagnosis of infection.
The commercial ELISA incorporates recombinant antigens of Plasmodium spp. while in-house ELISAs incorporate the crude extract of P. falciparum. The serum samples of individuals with and without clinical history of malaria were used as negative controls. In this study, it was possible to test the antigens of P. spp. in humans and mice.
The new ELISA test has a higher sensitivity than the previous ELISA tests for malaria. Furthermore, the test's specificity is similar to the existing ones, allowing it to distinguish between past and ongoing infections. These tests are highly sensitive and specific, which is vital for malaria diagnosis. There are no other tests that compare these two tests. If they were to work in the same way, they would provide reliable results and increase patient safety.