For a comprehensive assessment of the state of the body, an ELISA diagnostic method is used. ELISA blood test is designed to diagnose infectious, hematological, primary and secondary immunodeficiencies.
What is ELISA analysis
Many patients are interested in the ELISA method: what is it, what is the study for. Enzyme immunoassay has been used relatively recently. Initially, it was used to study antigenic structures, and it was carried out only for scientific purposes. Then the scientists came to the conclusion that with the help of enzymes it is possible to identify specific antibodies that arise in response to an ongoing disease.
Initially, this technique was used only by narrow-profile medical institutions, mainly at blood transfusion stations. Of particular importance is the ELISA method for detecting HIV infection.
Today, this method has a wide scope. Modern laboratories use it for diagnosis:
- tumors;
- hormonal disorders;
- infections;
- chronic or past infectious processes;
- helminths.
If in the bodyan infectious process occurs, then this type of diagnosis is considered the most optimal for determining the type of disease.
The essence of the method and its types
ELISA method - what is it, what is the essence of this type of research? This and many other questions are of interest to patients. The basis of this diagnostic method is the binding of the body's immune cells to the antigens of infectious agents. The resulting complex is determined using a special enzyme.
To understand the principle of the ELISA method, you need to know how the antigen-antibody reaction works. An antigen is a protein molecule foreign to the body that enters along with the infection. Particles of foreign blood that do not match in group are also considered antigens. In the body, they provoke an immune response aimed at protecting against foreign substances. Therefore, the human body produces antibodies - immunoglobulins that can attach to antigens, forming an immune complex. Such compounds are much easier to recognize and destroy by immune cells.
The reaction for the presence of such immune complexes is carried out in the laboratory, using ready-made compounds to determine whether there are similar ones in the blood.
The essence of the ELISA method is quite simple, however, due to the fact that a blood test is performed to detect many infections and diseases, there are several of its varieties. Each differs in the scheme of conduct and scope. May be direct or indirect ELISA. The direct method implies that immobilized antibodies are used,reacting with antigens. The main advantage of this method is that all processes can be automated, which means that diagnostics takes a little time.
Indirect method implies that secondary antibodies are used. And on the solid phase, the antigen is immobilized. The analysis allows you to determine antibodies to various antigens. This helps to achieve a more accurate result, but the method is complicated.
Research Benefits
Laboratory studies by ELISA have many advantages over other diagnostic methods. The main ones include:
- high sensitivity;
- storage stability of ingredients;
- speed of diagnostics;
- may apply a small amount of test material;
- it is possible to automate all processes;
- it is possible to detect the infection at the earliest stages.
This diagnostic method is universal, therefore suitable for mass examination. With the help of analysis, it is possible to trace the dynamics of the infectious process.
Indications for analysis and material sampling
A study using the ELISA method can be prescribed for suspected many diseases:
- acute and chronic infections, venereal diseases;
- presence of parasites;
- autoimmune pathologies;
- oncological diseases;
- to determine the level of hormones.
For the presence of antibodiesvenous blood is examined. Before analysis, elements that can complicate the study are isolated from it. Other biological fluids may also be sampled.
To get the most accurate information, blood is taken on an empty stomach. If the procedure was prescribed to determine a latent infection, then a few weeks before the analysis, you should stop taking antibacterial and antiviral drugs. Depending on the equipment of the laboratory where the material was taken, the result can be obtained within a day. In emergency cases, this time is reduced to a few hours.
Syphilis test
Using the ELISA method helps to determine the presence of many infections in the body, in particular syphilis. For the study, blood is taken from a vein on an empty stomach. Then a study is carried out that helps to determine not only the presence of the disease in the body, but also the exact timing of its onset, since during the course of the disease some antibodies are replaced by others in a strictly defined order.
In the acute phase, indicating a prolonged course of the disease, or during an exacerbation of a chronic infection, type M immunoglobulins will be detected in the blood. The presence of type A immunoglobulins indicates that the infection lives in the body for more than 4 weeks. Group G immunoglobulins indicate the height of the disease or previous therapy.
According to the degree of color of the wells, the intensity of the course of the infectious process is estimated, sohow its saturation depends on the amount of immune complexes formed.
HIV test
ELISA method is also used to test for HIV infection. Diagnosis in this case has certain features that are associated with the course and progression of the disease. This research method is considered the most acceptable for determination, however, it should be carried out no earlier than a month after exposure to risk factors. This is due to the presence of an incubation period that runs from 45 days to 6 months. That is why the analysis needs to be repeated in six months.
A positive result is considered if antibodies were detected during the initial examination. In this case, the analysis is repeated after six months, if again the result is positive, then the study is carried out using highly specific test systems.
Analysis for parasites
Quite often, doctors prescribe an enzyme immunoassay to determine the presence of parasites in the body. Using this research method, you can determine:
- ascariasis;
- giardiasis;
- toxoplasmosis and others
ELISA blood diagnostics is used to detect parasites and their waste products, as well as immunoglobulins. The effectiveness of this method is 90% and helps to track the dynamics of the development of processes.
Disadvantages of the method
Despite all the advantages, there are also disadvantages of the ELISA method. The main disadvantage is that whenresearch doctor must have an assumption about the disease in advance.
When diagnosing infectious diseases, there is no way to accidentally find the pathogen and determine its enzyme immunoassay properties. The test only indicates the presence of antibodies in the patient's blood. In addition, this is a rather expensive analysis.
Transcription of analysis
The result of a qualitative ELISA will be either the presence of antibodies or their absence in the blood. If a quantitative analysis is carried out, then the concentration of antibodies can be expressed either in a numerical value, or in a certain number of characters +.
In addition, indicators such as:
- IgM;
- IgA;
- IgG.
The IgM indicator indicates the course of an acute infectious process in the body. Its complete absence may indicate the absence of the causative agent of the disease or its transition to the chronic stage.
An IgA reading with a negative IgM test indicates a chronic or latent infection. The simultaneous presence of IgM and IgA indicates that the disease is in an acute stage. The presence of IgG indicates the transition of the disease to the chronic stage or full recovery and the development of immunity.
Now there are special ELISA tests that you can do yourself.
