Recommendations: Examination for the presence human immunodeficiency virus (HIV) should be carried out periodically in persons receiving treatment for sexually transmitted diseases, drug addicts, homosexuals, bisexuals and other persons belonging to risk groups. HIV testing should also be offered to pregnant women and women who are at risk of pregnancy and who are at risk for HIV.

HIV testing should not be carried out without consent and without appropriate consultation before and after the test, physicians should be careful in the use of appropriate tests and laboratories. Individuals with a positive serological result require appropriate post-test counselling. Immediate establishment of sexual partners is required. Individuals who test negative also require post-test counseling and retesting as directed.

It is estimated that 1-1.5 million people in the US infected with HIV. Over 10 years of HIV development, approximately 50% of those infected developed acquired immunodeficiency syndrome (AIDS), the rest - other clinical diseases associated with HIV infection. There is currently no treatment that can prevent death in AIDS patients. In a pre-licensed study of AZT (azidothymidine, zidovudine), only half of the patients survived more than a year after diagnosis; only 15% lived more than 5 years. Of the 82,764 cases reported by the CDC at the end of 1988, 56% (over 46,000 patients) died, of which more than 80% were diagnosed before 1985.

AIDS- the only thing serious disease in the United States, the death rate from which is increasing. The incidence is highest among young people (25-44 years old), and AIDS is one of the main reasons for the reduction in potential life expectancy. Between 1984 and 1987, AIDS went from being the 130th to the 7th leading cause of life expectancy being shortened to 65 years. AIDS is the leading cause of death among drug addicts (IV) and hemophiliacs. Between the discovery of AIDS in 1981 and the end of 1988, 82,764 cases of AIDS were reported. It is predicted that by the end of 1992 more than 365,000 cases will be reported and 260,000 people will die of AIDS. The United States currently spends $2.2 billion on the fight against AIDS. These expenditures are to rise to 12 billion in 1992.

HIV infection mainly observed in homosexuals and bisexuals, drug addicts and people with heterosexual contacts with infected people. Other risk groups include blood transfusion recipients with hemophilia and children born to infected mothers. Seropositive results range from 20% to 50% among homosexuals and bisexuals, depending on the place of residence, and from 5% to 50-65% among drug addicts living in metropolitan areas such as New York. Blacks make up 36% of all reported AIDS cases and 16% are Hispanics.

Depending on the geographical area, the number of women giving birth, infected with HIV, ranges from 0.02 to 3%. There is information to suggest that HIV-infected pregnant women have higher mortality from viral diseases and a higher risk of developing AIDS. About 30-35% pass the virus on to their children. Three quarters of AIDS cases in children under 13 years of age are associated with perinatal infection.

Effectiveness of screening tests for HIV infection.

The main screening test for the detection of antibodies to HIV is enzyme binding immunoassay (ELISA or EIA). ELISA has an efficiency and sensitivity of about 99% when the supplied set of components is used under optimal laboratory conditions. In common practice, false-positive and false-negative reactions appear more often. False-negative reactions usually occur due to biological causes in the first 6-12 weeks after infection, when the body of HIV-infected people has not yet had time to develop a detectable number of antibodies. False-positive reactions may be due to specific serological reactions in individuals with immunological diseases or multiple diseases. To reduce the likelihood of false positive reactions, an ELISA assay in a series of consecutive tests can have a specificity of up to 99.8%. However, even this excellent sensitivity leads to low HIV-positive early detection rates when testing is performed in a low-risk group.

It is shown that three out of four individuals who have a positive reaction with repeated ELISA test for HIV infection, have a false-positive reaction when the prevalence of the disease is 30 per 100,000 (the ELISA test is assumed to have a sensitivity of 98% and a specificity of 99.8%).

It is also necessary to confirm the ELISA results by independent tests of high specificity for HIV infection(eg, "Western spot", radioimmunoassay methods, and indirect immunofluorescent methods). "Western spot" is the most common of these tests in the US.

Delivered in accordance with the standards of sequential ELISA tests for HIV infection with the final West Spot test having a false positive rate of less than 0.001%. An important problem is that many laboratories do not use standardized methods for working with the West Spot test, since the accuracy of the test is highly dependent on the choice of chemicals, the qualifications of technical personnel and methods for analyzing results, laboratories that lack proper quality control give more false-positive and false-negative results than observed in the case of optimal conditions.

In addition, some implicit combinations of virus-specific protein groups can cause positive for HIV infection when using the Western Spot test. It may also be necessary to correct false-positive ELISA results in cases where the "Western Spot" is inconclusive. This happens in 15-20% of tests performed in low-risk groups. If the face is not infected, then "Western spot" may not produce results for several months. The future use of viral cultures may create a third round of diagnostic tests to reduce the risk of diagnostic error.

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Timely diagnosis of HIV infection becomes an extremely important measure, since earlier treatment can largely determine the further development of the disease and prolong the life of the patient. In recent years, significant progress has been made in identifying this terrible disease: the old test systems are being replaced by more advanced ones, examination methods are becoming more accessible, and their accuracy is significantly increased.

In this article, we will talk about modern methods diagnosis of HIV infection, which is useful to know for the timely treatment of this problem and maintaining the normal quality of life of the patient.

Methods for diagnosing HIV

In Russia, for the diagnosis of HIV infection, a standard procedure is carried out, which includes two levels:

• ELISA test system (screening analysis);
• immune blotting (IB).

Other diagnostic methods can also be used:

• express tests.

ELISA test systems

At the first stage of diagnosis, a screening test (ELISA) is used to detect HIV infection, which is based on HIV proteins created in laboratories that capture specific antibodies produced in the body in response to infection. After their interaction with the reagents (enzymes) of the test system, the color of the indicator changes. Further, these color changes are processed on special equipment, which determines the result of the analysis performed.

Such ELISA tests are able to show results within a few weeks after the introduction of HIV infection. This analysis does not determine the presence of the virus, but detects the production of antibodies to it. Sometimes, in the human body, the production of antibodies to HIV begins after 2 weeks after infection, but in most people they are produced at a later date, after 3-6 weeks.

There are four generations of ELISA tests with different sensitivities. In recent years, III and IV generation test systems have been more frequently used, which are based on synthetic peptides or recombinant proteins and have greater specificity and accuracy. They can be used to diagnose HIV infection, monitor HIV prevalence, and ensure safety when testing donated blood. The accuracy of III and IV generation ELISA test systems is 93-99% (more sensitive are the tests that are produced in Western Europe - 99%).

To perform an ELISA test, 5 ml of blood is taken from the patient's vein. Between the last meal and the analysis should be at least 8 hours (as a rule, it is performed in the morning on an empty stomach). Such a test is recommended to be taken no earlier than 3 weeks after the alleged infection (for example, after unprotected intercourse with a new sexual partner).

The results of the ELISA test are obtained after 2-10 days:

• negative result: indicates the absence of HIV infection and does not require a referral to a specialist;
• false-negative result: can be observed in the early stages of infection (up to 3 weeks), in the later stages of AIDS with severe immune suppression and with improper blood preparation;
• false positive result: it can be observed in some diseases and in case of improper blood preparation;
• positive result: indicates infection with HIV infection, requires an IB and the patient's referral to a specialist in an AIDS center.

Why can an ELISA test give false positive results?

False-positive results of an ELISA test for HIV can be observed with improper processing of blood or in patients with such conditions and diseases:

• multiple myeloma;
• infectious diseases provoked by the Epstein-Barr virus;
• state after ;
• autoimmune diseases;
• against the background of pregnancy;
• condition after vaccination.

For the reasons described above, non-specific cross-reacting antibodies may be present in the blood, the production of which was not provoked by HIV infection.

In recent years, the frequency of false positive results has significantly decreased due to the use of III and IV generation test systems, which contain more sensitive peptide and recombinant proteins (they are synthesized using in vitro genetic engineering). After the use of such ELISA tests, the frequency of false positive results has significantly decreased and is about 0.02-0.5%.

A false positive result does not mean that a person is infected with HIV. In such cases, WHO recommends another ELISA test (mandatory IV generation).

The patient's blood is sent to a reference or arbitration laboratory marked "repeat" and tested on a IV generation ELISA test system. If the result of the new analysis is negative, then the first result is recognized as erroneous (false positive) and IB is not carried out. If the result is positive or doubtful during the second test, the patient is required to undergo IB in 4-6 weeks to confirm or refute HIV infection.

immune blotting

A definitive diagnosis of HIV infection can only be made after a positive immune blotting (IB) result is obtained. For its implementation, a nitrocellulose strip is used, on which viral proteins are applied.

Blood sampling for IB is performed from a vein. Then it is subjected to special treatment and the proteins contained in its serum are separated in a special gel according to their charge and molecular weight (the manipulation is carried out on special equipment under the influence of an electric field). A nitrocellulose strip is applied to the blood serum gel and blotting (“blotting”) is carried out in a special chamber. The strip is processed and if the materials used contain antibodies to HIV, they bind to the antigenic bands on IB and appear as lines.

IB is considered positive if:

• according to American CDC criteria - there are two or three lines gp41, p24, gp120 / gp160 on the strip;
• according to American FDA criteria - there are two lines p24, p31 and a line gp41 or gp120 / gp160 on the strip.

In 99.9% of cases, a positive IB result indicates HIV infection.

In the absence of lines - IB is negative.

When identifying lines with gp160, gp120 and gp41, IB is doubtful. Such a result can be detected when:

• oncological diseases;
• pregnancy;
• frequent blood transfusions.

In such cases, it is recommended to perform a second study using a kit from another company. If, after additional IB, the result remains doubtful, then follow-up is necessary for six months (IB is performed every 3 months).

polymerase chain reaction

The PCR test can detect the RNA of the virus. Its sensitivity is quite high and it allows detecting HIV infection as early as 10 days after infection. In some cases, PCR can give false positive results, because its high sensitivity can also react to antibodies to other infections.

This diagnostic technique is expensive, requires special equipment and highly qualified specialists. These reasons do not allow it to be carried out during mass testing of the population.

PCR is used in such cases:

• to detect HIV in newborns who were born to HIV-infected mothers;
• to detect HIV in the "window period" or in case of doubtful IB;
• to control the concentration of HIV in the blood;
• for the study of donor blood.

Only by the PCR test, the diagnosis of HIV is not made, but is carried out as additional method diagnostics to resolve disputes.

Express Methods

One of the innovations in HIV diagnostics has become rapid tests, the results of which can be assessed in 10-15 minutes. The most efficient and accurate results are obtained with immunochromatographic tests based on the principle of capillary flow. They are special strips on which blood or other test fluids (saliva, urine) are applied. In the presence of antibodies to HIV, after 10-15 minutes, a colored and control strip appears on the test - a positive result. If the result is negative, only the control line appears.

As with ELISA tests, rapid test results should be confirmed by IB analysis. Only then can a diagnosis of HIV infection be made.

There are express kits for home testing. The OraSure Technologies1 (USA) test is FDA approved, available without a prescription, and can be used to detect HIV. After the test, in case of a positive result, the patient is recommended to be examined in specialized center to confirm the diagnosis.

The remaining tests for home use have not yet been approved by the FDA and their results can be very questionable.

Despite the fact that rapid tests are inferior in accuracy to IV-generation ELISA tests, they are widely used for additional testing of the population.

You can get tested for HIV infection at any polyclinic, the Central Regional Hospital or at specialized AIDS centers. On the territory of Russia, they are held absolutely confidentially, or anonymously. Each patient can expect to receive medical or psychological advice before or after the analysis. You will have to pay for HIV tests only in commercial medical institutions, and in public clinics and hospitals they are performed free of charge.

For information on how you can get HIV infection and what myths exist about the possibilities of getting infected, read

The diagnosis of HIV infection can be established in the laboratory by detecting specific antibodies to the virus. In many other viral diseases, the presence of antibodies indicates a past infection. However, since HIV infection develops into a chronic infection, seropositive individuals are not only actively infected, but also contagious.

A serological test for detecting the presence of antibodies to HIV became widely available in 1985. The most commonly used method is enzyme-linked immunosorbent assay (ELISA), but other types of antibody tests are being developed, such as particle agglutination and "dot" ELISA. Tests can be performed quickly and easily and do not require complex equipment.

Although the above tests are highly sensitive, they can also give false results, and a positive result needs to be further confirmed by an additional test such as Western blot or indirect immunofluorescence.

It is also possible to directly determine HIV antigens (virus or viral protein) in semen; industry produces the necessary sets of reagents. These assays were originally designed as an attempt to provide a laboratory indication of the presence of infection during the window between infection and antibody production, which typically lasts 4 to 16 weeks. Antigen assays are now being used more widely to monitor the outcome of antiviral treatment in AIDS patients.

Screening programs for HIV infection (i.e. screening the entire population, or individual groups population to determine infection or disease) can help:

• prevent transmission of the virus through blood and blood products, semen, tissues or organs for transplantation;
• obtain epidemiological information on the prevalence and incidence of HIV.

Whenever a screening program is discussed, all questions noted in the WHO statement (Annex 4) should be clearly stated and addressed. Poorly designed and poorly implemented programs can harm public health and waste resources. Public health needs and human rights are best served by careful consideration of a range of technology, logistics, and social, legal and ethical issues before a decision is made to proceed with a screening program.

Mandatory HIV screening has a very limited role in AIDS prevention and control programmes.

Routine screening of donors helps prevent the transmission of HIV through blood, semen, or other cells, tissues, and organs. Part of such screening is informed consent by the individual and consultations, which must be kept confidential.

The identification of seropositive individuals through a survey allows determining the epidemiological type of HIV, which is necessary to assess areas and populations in need of special educational programs or other preventive services. These surveys should be conducted using methods that do not threaten respect for human rights. They should be carried out during the consultation, either with the consent of an informed individual, while respecting confidentiality, or in an anonymous, free manner (without recording other personally identifiable data).

Voluntary AIDS testing can be part of health care for suspected HIV-related illnesses, and can be integrated with information, education, counseling and other support services to promote sustainable behavior change. In voluntary HIV testing, obtaining consent from an informed individual and being able to receive counseling while maintaining confidentiality are very important. Voluntary HIV testing services should be widely available as part of AIDS prevention and control programs and access to such services should be facilitated.

The primary stage (screening) of HIV testing.

Attention! When passing the study of AT and AG to HIV 1/2 for the primary screening study in accordance with the legislation of the Russian Federation It is mandatory to provide the following data and documents:

1) For residents of Moscow and the Moscow region

• Full Name
• Day, month and year of birth
• Registration Information
• The passport
• Insurance policy (series and number insurance policy, name of the insurance company).

2) For residents of other regions of the Russian Federation and foreign citizens, additionally - a photocopy (scan) of the passport.

• Full Name
• Day, month and year of birth
• Registration Information
• Insurance policy (series and number of the insurance policy, name of the insurance company)
• The passport

In case of not providing the above information, for patients with preliminary positive and doubtful results of the screening of the study of AT and AG to HIV ½ (screening) (qual), the result of the study cannot be issued.

The analysis can be submitted anonymously: in this case, the patient is registered as anonymous with an individual order number (clause 2, article 8 of the Federal Law of the Russian Federation No. 38-FZ), with the obligatory indication of the year of birth and place of residence (subject of the Russian Federation).

Draw your attention to! That the results of the primary (screening) study are only the results of a laboratory study and are not the result of an examination or a conclusion about the presence or absence of HIV infection. Based on the results of the screening study, you should contact the municipal AIDS center for a voluntary examination for the presence of HIV.

The results of an HIV test, regardless of their result, are issued only when the patient personally contacts the laboratory department. When examining minors (under 14 years old) children - the legal representative specified in the order.

The results are issued upon presentation of an agreement, an estimate and an identity document of the patient himself or the patient's representative specified in the order.

Research results are not communicated by phone or email.

With this test, test serum/plasma samples can be simultaneously tested for the presence of HIV type 1 and type 2 antigen and HIV type 1 and type 2 antibodies.

The human immunodeficiency virus belongs to the family of RNA-containing retroviruses and the subfamily of lentiviruses, i.e. slow infection viruses. HIV is genetically and antigenically heterogeneous, in its structure it is divided into types 1 and 2. When introduced into human cells, the virus forms a segment of DNA in their genome, which later forms new HIV in unlimited quantities. Virus antigens appear on the surface of damaged cells. The answer to their appearance from the outside immune system is the formation of specific antibodies to the virus of the first or second type. Over the past three years, the number of officially registered HIV-infected persons in Russia has been growing exponentially. The rapid spread of HIV infection in the country may become uncontrollable. Therefore, one of the main tasks at present is the use of more advanced methods for its diagnosis, which ensure the identification of infected individuals at the earliest stages of infection. These methods include laboratory serological tests that determine both the protein structures of the virus and specific antibodies to the virus.

Indications for the appointment of the study

1. Increase lymph nodes more than two areas;
2. Leukopenia with lymphopenia;
3. night sweats;
4. Sharp weight loss unclear reason;
5. Diarrhea for more than three weeks of unknown cause;
6. Fever of unknown cause;
7. Planning for pregnancy;
8. Preoperative preparation, hospitalization;
9. Identification of the following infections or their combinations: tuberculosis, manifest toxoplasmosis, often recurrent herpesvirus infection, candidiasis of internal organs, repeated herpes-zoster neuralgia, pneumonia caused by mycoplasmas, pneumocysts or legionella;
10. Kaposi's sarcoma at a young age;
11. Casual sex.

Study preparation

It is recommended to donate blood in the morning, between 8 a.m. and 11 a.m., on an empty stomach (at least 8 hours should elapse between the last meal and blood sampling, you can drink water as usual), on the eve of the study - a light dinner with restriction of fatty foods.
1-2 hours before donating blood, refrain from smoking, do not drink juice, tea, coffee, you can drink non-carbonated water. Eliminate physical stress (running, fast climbing stairs), emotional arousal. It is recommended to rest and calm down 15 minutes before donating blood.

and

Antibodies to HIV 1/2- components of blood plasma, of a protein nature, which prevent the reproduction of HIV infection and completely neutralize their negative impact.

What is an HIV antibody test 1/2 (screening)

Screening analysis for antibodies to HIV 1,2 - a system of tests that allow you to identify people infected with the immunodeficiency virus. In addition to these, there are so-called confirmatory (auxiliary) tests, the task of which is to identify individuals not infected with the virus, but with a positive reaction to the virus during screening.

The essence of the screening study of HIV infection is to determine antibodies to the immunodeficiency virus. His distinguishing feature in hypersensitivity - more than 99.5%. The specificity of testing is that screening can give a false positive result if the patient's body contains autoantibodies.

An identical result can be detected in the case of liver disease in a patient, influenza vaccination or the presence of any acute viral disease. Based on this, in order to obtain accurate results, along with screening, it is usually customary to do the above-mentioned confirmatory test.

Indications for analysis

In medical practice, there is a fairly wide range of indications for screening. The patient may apply for:

• suspicion of infection (if there was close contact with a carrier of HIV infection);
• with weight loss, fever;
• pneumonia, which is not amenable to conventional therapy;
• diseases of a chronic nature that arose for unknown reasons;
• in preparation for surgery;
• blood transfusions;
• pregnancy and family planning;
• With inflamed lymph nodes;
• Casual sex.

Persons falling into a special risk group: drug addicts and people leading a promiscuous sex life.

How is HIV antibody screening done 1/2

The procedure involves compliance with a number of necessary rules:

• the patient must donate blood exclusively on an empty stomach (it is allowed to drink water);
• at least eight hours must have passed since the last meal;
• the doctor should be informed about what medications the patient is taking and know the dosage (if there is no possibility of even short-term cancellation);
• if the patient is able to delay the use medicines, he is recommended to do this 10-15 days before the day of manipulation;
• the day before the start of testing, it is advisable for the patient to refuse to take fried or fatty foods, he is also forbidden to drink alcoholic beverages, smoke, and limit heavy physical exertion.

It should be noted that laboratory research for the presence of infection in children who were born to mothers who are carriers of the immunodeficiency virus, have their own specifics.