HIV infection changes in blood tests. Diagnostic methods for HIV infection - general, confirmatory and special blood tests. Leukocytes and viral load

It is best to find out about the presence of the immunodeficiency virus at the first stage. The sooner the presence of a problem becomes known, the greater the likelihood that the patient will live long life. Despite the fact that today specialists have a huge amount of information about the virus, they can successfully cope with it only during the first period of its occurrence.

A routine blood test is a fairly effective way to detect the disease. On early stages the occurrence of pathology, he is able to recognize the presence of a problem in the patient’s body. Traditionally, the material is taken from a millimeter cut on the fingertip; this method is well known to every person since childhood. The procedure must be carried out on an empty stomach in the morning. Even such a tiny amount of biological fluid can tell medical professionals about all the processes occurring in the patient’s body. The result will be known very soon.

Blood test for HIV (AIDS): explanation

In case of immunodeficiency, a general analysis recognizes:

• lymphopenia - a deficiency of lymphocytes, leading to a serious deterioration of immunity;
• lymphocytosis - a change in the composition of the blood during HIV infection, in which there is an excess of lymphocytes, meaning the body’s independent fight against the newly emerging immunodeficiency virus;
• neutropenia - a lack of neutrophils in the bone marrow. This blood indicator is not always present in HIV infection or may indicate other diseases not related to immunodeficiency;
• thrombocytopenia - a lack of platelet count that can lead to serious problems with coagulability. This, in turn, makes it difficult to stop internal and external bleeding.

Any, even minor changes in the general analysis will arouse suspicion from the doctor. With HIV infection, changes in the blood are always present and this is the only thing that immediately indicates this disease. Further examinations will be scheduled.

It is necessary to recognize the presence of antibodies to the retrovirus using ELISA. In the enzyme immunoassay of blood for HIV, the decoding hbs and hcv is also indicated. The presence of antibodies manifests itself in 90% of all infected people in the first 3 months after the onset of the disease.

A doctor can tell you what a blood test shows for HIV. The study is often done as a precaution. It shows the number or relationship of certain types of leukocytes that take part in the formation of antibodies that support immunity. The method determines the number of natural killer -NK cells, B cells and the number of healthy cells.

How to interpret a blood test for HIV?

What kind of blood is there for HIV - you need to check it again after 4 weeks. If a virus is present, the attending physician will immediately help in deciphering the blood for HIV and inform the patient about the necessary actions. A repeated test will show what changes have occurred in the blood due to HIV and, if its composition does not change after a certain period of time, the result is accurate. Initially, the result may be positive due to a list of other diseases not related to AIDS. Blood counts in HIV infection change 14 days after infection, p24 Ag appears, which is detected by ELISA ( linked immunosorbent assay) in the very near future.

What blood indicators indicate HIV is something everyone needs to know. In AIDS, antibodies to Ag p24 of the IgM and IgG classes appear in the early stages and can persist for years. The norm is the complete absence of antibodies to HIV in human blood and the p24 antigen. ELISA is considered the most accurate way to detect the virus. According to its transcript, if there are no antibodies, then the result is negative.

The transcript of the analysis always shows a positive or negative result. It should be remembered that false negative result, which means the study should be repeated in a few months. Positive result may also be false. This is due to the fact that the patient may have other pathologies. To exclude this possibility, you need to take an additional special IB test (immunoblot), which will reveal the cause and characteristics of existing antibodies. At the earliest stage, a blood test for HIV shows the norm, so the pathology often goes unnoticed.

There is another test for identifying the immunodeficiency virus - PCR. This method is very common in early diagnosis in children in the first year of life. It determines the hereditary material (DNA and RNA), which shows the ability to reproduce itself. This method is distinguished by its accuracy and ability to “see” the virus after two weeks after infection.

Do not forget that normal blood levels in HIV are also often observed if the pathology develops at an early stage.

White blood cells in HIV significantly change their level - this is due to the fact that the cells and proteins responsible for fighting diseases are the first to be affected. It is thanks to these changes that it becomes possible to calculate the immunodeficiency virus at the very beginning of its development, without waiting for characteristic signs to appear.

This is extremely important: only if the disease has been identified at an early stage is it possible to fight it and make the patient’s future life longer and more comfortable. A general blood test can help with this.

General blood test parameters

A general blood test is a routine test that is taken from a finger prick and examines the following parameters:

1. Leukocyte level.
2. Red blood cell level and ESR.
3. Hemoglobin level.

Leukocytes are white blood cells that provide protection to the body from diseases, tumor development and other similar problems. They are responsible for the level of immunity.

As a rule, people suffering from HIV infection have the following characteristics:

HIV carriers should have a general blood test every 3 months - this allows you to monitor the progress of the disease and take therapeutic action in time if it begins to develop faster than usual.

Changes in white blood cell levels are an ambiguous sign of HIV infection

Fluctuations in leukocyte levels may occur due to various reasons. The reasons causing such changes are divided into pathological and physiological.

Pathological processes causing an increase in leukocytes:

1. Inflammatory diseases, during which purulent processes occur.
2. Diseases that cause tissue necrosis: heart attacks, strokes, burns.
3. Intoxication.
4. Hypoxemic diseases.
5. Development of malignant tumors.
6. Development of leukemia.
7. Diseases that cause immune reactions.

Physiological processes that cause an increase in leukocytes:

1. Taking protein foods in large quantities.
2. Severe physical stress.
3. Severe emotional stress.
4. Overheating or hypothermia of the body.

Pathological processes causing a decrease in leukocytes:

1. Viral infections.
2. Bacterial and protozoal infections.
3. Generalized infections.
4. Autoimmune diseases.
5. Aleukemic leukemias.
6. Diseases of the endocrine system.
7. Hypersplenism syndrome.

Changes in leukocyte levels in themselves do not indicate any specific disease. This is why, as a rule, additional tests are required.

CD4 level test. Viral load test

In HIV, leukocytes are the first to suffer, since the immunodeficiency virus attacks cells containing the protein receptor type CD4 - and the majority of such cells are lymphocytes.

CD4 test

CD4 is a rather difficult indicator to analyze. Nevertheless, determining its level is considered an integral part of HIV diagnosis.

When analyzing CD4, it is important to consider the following features:

• availability of physical and emotional stress in the patient;
• his nutrition;
• time of blood sampling.

Normal CD4 levels look like this:

It is the indicator, ranging from 0 to 3.5, in combination with a decrease in the level of leukocytes that becomes a clear indicator of the need for antiretroviral therapy.

During diagnosis, in order to eliminate the possibility of distortion of the analysis of the CD4 level by certain factors, another parameter is used. This is the ratio of the number of CD4 cells to the number of CD8 cells. CD8 is a different type of receptor that is not affected by the HIV virus, and their ratio in healthy body must be greater than 1.

Viral load test

A viral load test usually makes it possible to definitively diagnose the presence of HIV in the body.

This analysis examines the amount of HIV RNA fragments in the blood. U healthy person such a result will be undetectable.

This analysis is also needed to monitor the progression of the disease by monitoring the increase in the number of RNA fragments.

HIV testing is often done purely as a precaution. They are important for pregnant women, as well as those people who suspect the possibility of infection after sexual contact or contact with unsterile surgical instruments and needles.

HIV is not transmitted through household objects, and it is quite difficult to become infected with it at home.

HIV infection is a disease caused by the human immunodeficiency virus (HIV), long time persisting in lymphocytes, macrophages, cells of nervous tissue, resulting in the development of slowly progressive damage to the immune and nervous systems body, manifested by secondary infections, tumors, subacute encephalitis and others pathological changes. The causative agents are human immunodeficiency viruses types 1 and 2 - HIV-1, HIV-2, (HIV-I, HIV-2, Human Immunodeficiency Virus, types I, II) - belong to the family of retroviruses, a subfamily of slow viruses. The viral particle has a spherical shape with a diameter of 100−140 nm with an outer phospholipid shell, which includes glycoproteins (structural proteins) with a certain molecular weight, measured in kilodaltons. For HIV-1, these are gp 160, gp 120, gp 41. Inner shell The virus covering the core is also represented by proteins with a known molecular weight - p17, p24, p55 (HIV-2 contains gp 140, gp 105, gp 36, p16, p25, p55). Detection of antibodies (AT) to the human immunodeficiency virus is the main method laboratory diagnostics HIV infections. The method is based on ELISA (sensitivity - more than 99.5%, specificity - more than 99.8%). Also, to diagnose HIV infection, determination of the p24 antigen (Ag) by ELISA is used.

To reliably assess the result of an HIV test, it should be remembered that it depends on the time elapsed from the moment of potential infection:

1. a test for HIV infection performed immediately after potential infection is not informative, since antibodies to HIV have not yet formed. For this reason, it is advisable to perform the test no earlier than the 3rd week after potential exposure to the virus. The exception is for legal reasons (for example, for medical workers in case of injury from a needle containing biological material), when it is necessary to make sure that at the time of contact with a potential carrier of HIV infection, the patient did not have it;
2. HIV infection can be excluded with sufficient accuracy only 3 months after potential infection. Therefore, after contact with a carrier of the infection, it is necessary to perform a follow-up examination. However, repeating the test after 3 months (i.e. 6 months after potential infection) makes sense only in exceptional cases, for example, if there is a clinical suspicion of acute retroviral syndrome;
3. a negative test result is only reliable if there has been no re-exposure to the virus within the past three months.

If there is a clinical suspicion of acute HIV infection (acute retroviral syndrome, contact of a risk group with an HIV-infected person), it is advisable to perform HIV-PCR. Taking into account the possible false-negative result, in general cases, HIV-PCR can be used to exclude the fact of transmission of HIV infection, but only conditionally - it cannot replace a serological test for HIV. Therefore, the HIV-PCR method should only be used in addition to serological analysis, but not instead of it. HIV PCR method used routinely clinical practice, allows the detection of HIV-1 exclusively.

In some cases, rapid tests for HIV infection are performed. These tests provide quick results and are easy to use; they do not require the use of special equipment to perform or evaluate the results, so rapid tests can be used directly at the point of care. As a material for research, along with plasma and blood serum, whole or capillary blood (from a finger or earlobe), which does not require centrifugation, can also be used. Some test systems allow the use of urine or mucosal transudate oral cavity. The test shows the result within 15-30 minutes. Rapid tests are especially suitable for situations where the test result has immediate consequences. For example, this applies to situations such as emergency surgery or injury from a needle containing biological material. There are limitations to the use of this test regarding the diagnosis of HIV infection before seroconversion, since almost all available rapid tests only detect HIV antibodies, but not p24 antigen. Rapid tests should be used for an initial rough assessment only. They are not suitable for confirmation or exclusion acute infection. The result of the rapid test should be confirmed as soon as possible during routine laboratory research using a standard HIV test.

Indications for prescribing a blood test for HIV

Preparing for the test

The main condition for taking the test is refusing to eat at least 8 hours before the procedure, as well as a ban on alcohol.

How is the procedure performed?

Blood is drawn on an outpatient basis using standard technology - from a vein with a sterile syringe. 5 ml is enough for research.

Antibodies to human immunodeficiency virus in the blood

In case of HIV infection, antibody production begins no earlier than two weeks later.

Antigen p24 in blood serum

The p24 antigen can be detected approximately 5 days before the initial appearance of specific antibodies. Ag p24 is the HIV nucleotide wall protein. The stage of primary manifestations after HIV infection is a consequence of the onset of the replicative process.

Decoding the analysis result

4 weeks after infection, HIV-specific antibodies are detected in 60-65% of cases, after 6 weeks - in 80% of cases, after 8 weeks - in 90% of cases, after 12 weeks - in 95% of cases. During the AIDS stage, the amount of AT may decrease until it disappears completely. If a positive response is received (anti-HIV antibodies are detected), in order to avoid false-positive results, the test must be repeated one or two more times, preferably using a diagnostic kit from a different series. The result is considered positive if out of two - in both analyzes or out of three - AT is clearly identified in two analyses.

Ag p24 appears in the blood 2 weeks after infection and can be detected by ELISA in a period of 2 to 8 weeks. After 2 months from the onset of infection, Ag p24 disappears from the blood. In the future in clinical course HIV infections mark a second increase in the level of p24 protein in the blood. It falls during the formation of AIDS. Existing ELISA test systems for detecting Ag p24 are used for early detection of HIV in blood donors and children, determining the prognosis of the course of the disease and monitoring therapy. The ELISA method has high analytical sensitivity, which makes it possible to detect HIV-1 p24 Ag in blood serum at concentrations of 5−10 pkg/ml and less than 0.5 ng/ml HIV-2, and specificity. However, it should be noted that the content of Ag p24 in the blood is subject to individual variations, which makes it possible to identify only 20−30% of patients using this study in early period after infection.

Antibodies to Ag p24 of the IgM and IgG classes appear in the blood starting from the 2nd week, reach a peak within 2-4 weeks and remain at this level different times— IgM class antibodies last for several months, disappearing within a year after infection, and IgG antibodies can persist for years.

Norms

Anti-HIV 1/2 antibodies are normally absent in the blood serum.
The p24 antigen is normally absent in serum.

Diseases for which a doctor may prescribe a blood test for HIV

1. AIDS

   During the AIDS stage, the amount of AT may decrease until it disappears completely. During the period of AIDS formation, there is an increase in the level of p24 protein in the blood.

A complete blood test is not able to diagnose HIV infection in the body. But the presence of changes in the biomaterial gives grounds to prescribe additional examination person.

A general or clinical blood test (abbreviated as UAC) is a mandatory procedure during a clinical examination, and the process of collecting biomaterial from a finger is familiar to everyone since childhood. In fact, it is impossible to determine and unambiguously diagnose the HIV virus in human blood using the CBC. In this case, the primary stage of infection development will indicate to the fullest for some changes in biological material, on the basis of which additional examination techniques are carried out.

A CBC (complete blood count) is a simple process of drawing blood from a small cut on the finger. Based on the results of this analysis, the state of the entire body system as a whole can be assessed. In this case, the specialist is able to determine only some changes in common system, which provide grounds for carrying out additional research measures in laboratory conditions. But CBC does not give a chance to unambiguously diagnose HIV (human viral immunodeficiency).

A general blood test shows changes in the quantitative and qualitative composition of the body’s cells, which can indicate the presence of infectious or viral diseases .

Early detection and diagnosis of HIV infection is the most rewarding event for timely measures taken curing a person from the immunodeficiency virus. After all, the virus affects the immune system at the cellular level, which destroys the body’s ability to resist even simple infections and viruses. What makes immunodeficiency so dangerous is that if you do not take timely measures to stop or slow down the spread of HIV throughout the body, the process will soon consume the entire system, leaving a person without protection against simple diseases.

A blood test, or rather, its result, will only show changes that are endowed with the ability to prompt a specialist to take additional examination measures. What can a general analysis of blood sampling show:

• Lymphopenia. A general decrease in lymphocytes in the blood in quantitative terms.

Reduced content of T-lymphocytes – main feature deteriorated activity of the immune system and active development of the retro virus in the body. This indicator can determine the early stage of infection.

• Lymphocytosis. An increased quantitative indicator of lymphocytes in the blood will indicate a change in the leukocyte formula.

An increase in lymphocytes indicates that the body has responded to the infection entering the body, trying to independently contain the spread.

• Increased ESR(erythrocyte sedimentation rate).
• Neutropenia(blood cells produced in the bone marrow).

A decrease in the concentration of neutrophils (granular leukocytes) according to the analysis will show the decline of protective cells that are involved in the fight against pathogenic viral agents.

A complete blood test for HIV (human immunodeficiency virus) helps confirm or refute the presence of the disease. Definition of immunodeficiency early stages allows you to slow down the development of infection and prolong the life of the patient. A general blood test can detect the virus soon after it enters the body. Therefore, this study is prescribed if the disease is suspected. If the procedure shows changes, the patient is referred for additional examination to confirm the diagnosis.

In what cases is an HIV test prescribed?

HIV testing is usually considered a precautionary measure. This virus can live in the body for many years and not manifest itself in any way. This diagnosis is most often made by chance.

A person can be sent for a blood test for HIV in the following cases:

1. Before surgical interventions, in order to prevent the development of complications due to changes in blood parameters.
2. During the period of bearing a child. Pregnant women are prescribed this test several times. It is very important to identify the virus at the beginning of pregnancy, since if the mother is sick, the child will be born with the same problem, and gradually secondary pathologies will develop.
3. After unprotected sexual intercourse.
4. If a person got a tattoo or piercing in an unverified place.

Medical workers and donors need to be tested periodically: they are at risk because they may come into contact with contaminated blood.

You can become infected with the immunodeficiency virus only through bodily fluids or blood. With kisses, by airborne droplets, due to the use of common objects, this disease cannot spread from one person to another. IN living conditions very low risk of infection. This can only happen after sexual contact with a patient or if the needle used to take blood from the patient is used on another person.

What does a general blood test show?

Many people are interested in whether the general clinical trial show HIV. This procedure is prescribed for the diagnosis of any pathology. For the study, capillary blood is used, which is taken from a finger on the hand. Based on the results of the analysis, a specialist can detect any processes occurring in the body.

If the composition of blood cells changes, it means that an infectious or other kind of disease is developing. HIV is called the immunodeficiency virus because it immediately attacks the immune cells that are responsible for the body's resistance to infections. This feature is what makes the disease so dangerous.

If the virus is not detected in time and with the help medicines If its spread is not stopped, soon the immune system will be destroyed and a person may die from even the mildest infection.

A general analysis may show:

• increase in the content of lymphocytes in the blood. This process is called lymphocytosis. He can detect a problem in the early stages of development - the body begins to fight the virus that has penetrated it, which is manifested by an increase in lymphocytes;
• decrease in the content of lymphocytes in the blood. This process is called lymphopenia. It develops when the disease attacks immune system person;
• decreased platelet levels. This is thrombocytopenia. These cells are responsible for the ability of blood to clot. If their number decreases, then the risk of developing external or internal bleeding increases;
• decrease in neutrophil concentration. These blood cells are produced in the red bone marrow. A decrease in their number (or neutropenia) occurs when an infectious process begins to develop in the body. This indicator suggests the presence of immunodeficiency;
• decrease in hemoglobin level. This is due to the fact that with HIV, the functioning of red blood cells is disrupted. These cells carry oxygen throughout the body, so if hemoglobin falls, the person’s condition worsens;
• presence in the blood atypical mononuclear cells. These cells appear when a virus enters the body.

These indicators will indicate that an infection is developing and the doctor will refer you for additional tests.

Possible signs of illness

The human immunodeficiency virus does not always appear immediately. In some cases, for a long time a person may not even suspect the fate that has befallen him. But sometimes the body reacts very sharply to the penetration of a virus, so much so that it is, as they say, “unable to endure.”

This may present with symptoms of a common cold:

• headache;
• lymph nodes enlarge;
• severe weakness occurs;
• a sharp increase in temperature is possible.

After some time, the person’s well-being improves, he thinks that he just has a cold.

If the cause is HIV, then it is necessary to detect the disease, since the body cannot cope with it on its own and it needs to be influenced with medications. The virus is most often detected when it has already attacked the immune system.

This is accompanied by the following symptoms:

1. At the same time, several infectious diseases arise that are not affected by the prescribed therapy.
2. A person loses weight sharply and gets tired quickly. This happens because metabolic processes are disrupted.
3. There is a persistent increase in temperature to subfebrile levels.
4. The patient sweats a lot at night. This is also possible with other infectious pathologies.

It is very important to get tested for HIV even if you have no symptoms. This will help protect yourself and others.