Why is the ditch test positive? How long does it take for RW to test positive for syphilis after treatment? False-positive treponemal tests

False-positive serological reactions for syphilis (FPR)- these are positive reactions in people who have never been sick and do not have syphilis at the time of examination. That is, there is no specific infection in the body and there never was, and serological reactions give a positive result.

False positive or non-specific results are called positive results serological reactions for syphilis in persons who do not suffer from a syphilitic infection and have not had syphilis in the past.

Erroneous test for syphilis due to technical reasons

Decisional errors may be due to technical errors and errors during research, as well as the quality of reagents. Despite the numerous advantages of diagnostic tools for RPGA, ELISA and RIF and their modifications used for the diagnosis of syphilis, in some cases unreliable results analyses. This may be due to both an insufficient level of qualifications and professional responsibility of personnel (the so-called non-biological or technical errors), and to the characteristics of the tested samples (biological errors).

Non-biological errors can occur at any stage of research: pre-analytical, analytical, and post-analytical, i.e. when collecting, transporting, storing biomaterial, using chylous, sprouted serum, during repeated freezing and thawing of test samples, as well as when using expired diagnostics, etc. In particular, non-compliance with the storage conditions and periods of diagnostic kits causes a decrease in the sensitivity of the reaction and the receipt of false negative results.

False-positive results can be caused by contamination of the sera of patients seronegative for Treponema pallidum with traces of sera from seropositive individuals, which may occur during the preparation of the sera.

There are many other technical errors that lead to unreliable (false negative and false positive) and questionable research results. Some laboratories do not carry out internal and external quality control of syphilis tests, which leads to diagnostic errors and uncertainty among laboratory doctors in the results of the analysis.

The source of errors when performing nonspecific tests may be the failure to use control sera, uneven concentration of the antigen in the experiment due to insufficient mixing before use, contamination of samples and glassware with microorganisms, violation of the terms and conditions of storage of reaction components, and violation of blood collection techniques.

In modern test systems, recombinant or synthetic peptides have been used as antigens. The former became more widespread. But with poor purification, Escherichia coli proteins get into the mixture of T. pallidum antigens, which leads to false serodiagnosis of syphilis in patients with escherichiosis or in healthy people whose serum contains antibodies to E. coli.

To a certain extent diagnostic errors Incorrect interpretation of the research results should also be included.

Acute and chronic DM

In addition to technical errors when performing tests, decision-makers can also be caused by the characteristics of the body. Conventionally, decision makers are divided into spicy (<6 месяцев) и chronic(stored for more than 6 months).

Acute DM can be observed during pregnancy and during menstruation, after vaccination, after a recent myocardial infarction, and in many infectious diseases. Infections in which PPR may occur are pneumococcal pneumonia, scarlet fever, infective endocarditis, tuberculosis, leprosy, lymphogranuloma venereum, chancroid (chancroid), leptospirosis and other spirochetoses, HIV infection, infectious mononucleosis, malaria, chicken pox, viral hepatitis, mumps , measles, respiratory diseases, influenza and dermatoses.

Acute PDs are unstable, their spontaneous negativity occurs within 4-6 months.

Chronic DM possible with autoimmune diseases, systemic connective tissue diseases, cancer, chronic pathology of the liver and biliary tract, cardiovascular and endocrine pathologies, blood diseases, chronic lung diseases, injection drug use, etc. In most of these conditions, anticardiolipin antibodies of the IgG and IgM classes ("reagins").

Chronic false-positive reactions can remain positive throughout life.

Chronic false-positive reactions may be preclinical manifestations of serious diseases. In malignant neoplasms and diffuse connective tissue diseases, the LPR titer can be very high.

Among the causes of chronic positive reactions are physiological conditions (old age). With age, the number of PD increases; in women they are observed 4.5 times more often than in men. In the age group of 80-year-olds, the prevalence of PD is 10%.

The cause of DPR may be the frequent use of intravenously administered drugs, frequent transfusions and infusions.

Chronic infections (tuberculosis, leprosy, infective endocarditis, malaria), myeloma can also cause PD.

Infection with other spirochete species

False-positive reactions of treponemal and non-treponemal tests can be observed in infectious diseases whose pathogens are antigenically similar to Treponema pallidum. These are relapsing fever, leptospirosis, tick-borne borreliosis, tropical treponematoses (yaws, bejel, pinta), as well as inflammatory processes caused by saprophytic treponemas of the oral cavity and genitals.

The causative agents of endemic treponematoses (yaws, pinta, bejel) are treponemas that have genus-specific antigens similar to those of T. pallidum. In this regard, antibodies formed to them are capable of cross-interacting with the antigen of the causative agent of syphilis.

Russia is not a territory endemic for this group of diseases. These infections occur mainly in Africa, Latin America and South Asia, and cases of the disease are rare in the practice of medical institutions.

A patient with positive serological reactions for syphilis who arrived from a country with endemic treponematoses should be examined for syphilis and prescribed anti-syphilitic treatment if it has not previously been administered.

Biological false-positive Wasserman reaction

Beginning in 1938, and especially during World War II, serological screening tests for syphilis became widespread in the United States. The researchers compared the data obtained and found that a positive or questionable reaction was found in people who did not have clinical and epidemiological signs of syphilitic infection or contacts with syphilis. Moreover, such results occurred much more often than previously thought. Positive results of nontreponemal tests with lipid or cardiolipin antigens (VDRL, in Kolmer tests, Kahn reactions) have been found in patients with various diseases, but without signs of syphilitic infection. Biological false-positive results have been identified in patients with autoimmune, inflammatory and hematological diseases.

In Russian-language medical literature, this phenomenon is called “ biological false-positive Wasserman reaction"(B-LPRV), because These results were observed during the most common test of those times - the Wasserman reaction.

It turned out that B-LPRV can occur in two main forms - acute and chronic. In the first case, in patients who have had an infection other than a syphilitic infection, B-LPRV disappears during the recovery process, and the duration of its detection does not exceed six months. In the second case, B-LPRV may persist persistently for many years in the absence of an obvious causative factor. In the early 50s, it was found that chronic B-LPRV is most often detected in autoimmune diseases, especially SLE, in which the frequency of its detection reaches 30-44%

False-positive nontreponemal (cardiolipin) tests

Lipid antigens of T. pallidum make up a significant part of the cell, but the body may also contain lipids with the same structure - autoantigens formed as a result of the destruction of organs and tissues (mainly lipids of mitochondrial membranes).

Syphilitic infection is accompanied by the formation of immune complexes and an autoimmune response to cardiolipin, fibronectin, collagen and muscle creatine kinase. In non-treponemal tests, a solution of three highly purified lipids (cardiolipin stabilized with lecithin and cholesterol) in ethyl alcohol is used as an antigen. Cardiolipin is not a specific component for T. pallidum and is also described as one of the phospholipids of human biomembranes. Therefore, antibodies to this antigen are recorded in serum during almost any alteration of human cells as a result of infections and under some physiological and pathological conditions.

Because the antigen used in non-treponemal reactions is found in other tissues, tests may give positive results in individuals without treponemal infection (1-2% in the general population).

The most common cause of biological false-positive non-treponemal tests is antiphospholipid syndrome, an autoimmune process that occurs in connective tissue diseases (systemic lupus erythematosus, dermatomyositis, scleroderma).

When using non-treponemal tests (RMT and its modifications), false-positive results may be due to the presence in the blood of antibodies to rheumatoid factor, cross-reacting antibodies in autoimmune pathology (“cress reactors”).

Other factors for the occurrence of false-positive results are considered to be some chronic bacterial infections (leprosy, etc.), diseases of viral etiology (infectious mononucleosis), and systemic connective tissue diseases.

Reasons may also include old age (over 70 years), pregnancy, extensive somatic pathology, lipid metabolism disorders, immunodeficiency states of various etiologies, systemic chronic diseases of the heart and lungs.

Other causes include cancer, tuberculosis, enteroviral infections, viral hepatitis, Lyme disease, pneumonia, alcoholism, drug addiction, diabetes, vaccination, other infections (malaria, chicken pox, measles, endo- and myocarditis), gout.

In these conditions, the development of immunological disorders is observed, leading to abnormal production of antibodies that can cross-react with treponemal antigens.

Table. Biological causes of false-positive reactions in nontreponemal serological tests.

Spicy (<6 месяцев)	Chronic (>6 months)
Physiological conditions: Pregnancy Vaccination with some types of vaccines	Physiological conditions: Elderly age
Bacterial infections: Pneumococcal pneumonia Scarlet fever Infective endocarditis	Bacterial and other infections: Infective endocarditis Malaria
Mycobacterial infections: Tuberculosis Leprosy	Mycobacterial infections: Tuberculosis Leprosy
Other STIs: Chancroid (soft chancroid) Lymphogranuloma venereum	Connective tissue diseases: Systemic lupus erythematosus
Infections caused by other spirochetes: Relapsing fever Leptospirosis Lyme borelliosis	Oncological diseases: Myeloma Lymphoma
Viral infections: HIV Infectious mononucleosis Measles Chicken pox Mumps (mumps) Viral hepatitis	Other reasons: Injection drug addiction Multiple blood transfusions Diabetes

False-positive treponemal tests

Compounding the problem, treponemal tests can also be false positive. The causes may be autoimmune diseases, collagenosis, Lyme disease, pregnancy, leprosy, herpes, malaria, infectious mononucleosis, tumors, drug addiction. In recent years, immunoblotting, one of the most modern methods for diagnosing syphilis, has begun to be actively used abroad to differentiate DM.

Antibody persistence after successful treatment

Specific diagnostic reactions remain positive for a long time even after full therapy. After effective treatment of a syphilitic infection, in most patients, titers in non-treponemal tests decrease by 4 times 6–12 months after treatment. However, with late initiation of therapy, titers even in non-treponemal tests may remain at the same level, but never increase.

False negative test results

Different diagnostic methods demonstrate different sensitivity and specificity depending on the form and stage of syphilis. The likelihood of an erroneous diagnosis increases, especially in cases of latent, hidden, combined course of the disease.

False-negative serological reactions for syphilis can be observed in secondary syphilis due to the prozone phenomenon when testing undiluted serum, as well as when examining immunocompromised individuals, such as HIV-infected patients.

False-negative results of serological specific tests (SSR) caused by biological factors may be due to competition between specific IgM and IgG for binding to the antigen on the surface of erythrocytes, as well as the “prozone phenomenon”. In the latter case, agglutination does not occur due to overproduction of antibodies to Treponema pallidum, since each antigen receptor on erythrocytes, due to excess antibodies, is associated with one agglutinin molecule, which prevents the formation of a “lattice.” Replacing RPGA with TPPA, i.e. erythrocytes on synthetic particles, apparently, will eliminate or minimize the receipt of false negative results.

In ELISA, such reactions can be explained by the presence of a seronegative phase in primary syphilis, and in secondary syphilis - by immune deficiency and the presence of HIV infection. When receiving a negative result from serological tests for syphilis, one should take into account the ability of Treponema pallidum to penetrate and multiply in various organs and tissues - searching for the pathogen in the lymph (lymph nodes) in some cases leads to a reliable result. It is also advisable to repeat the analysis of samples that gave a positive result. Repeated examination of sera after 5–7 or more days, as a rule, allows one to obtain reliable results.

Most screening methods involve various blood tests. They are intended for mass examination of people in order to identify dangerous diseases. The technique for performing them (analysis from a vein or finger) and the price of the reagents are so simple and affordable that every state medical institution examines its patients for free. But recently, conflicting data have emerged regarding the blood test for RW. According to them, this research is not always as informative as previously thought.

What kind of analysis is this

The essence of a blood test for RW is to determine specific markers of syphilis. This sexually transmitted disease, like any infectious process, causes the appearance of antibodies, which provide an immune response and protect the body from the progression of the disease. The test that detects these specific antibodies is called the Wassermann reaction, or blood to RW.

How is it done and what kind of blood is needed for analysis?

The material for analysis can be any blood, either from a vein or from a finger. The specificity and reliability of the analysis depends on many factors. It is important to consider that this is a nonspecific test that has a large number of false positive and false negative results. Therefore, it cannot be relied upon with complete confidence in any case. This is due to the fact that blood from a finger can only be examined using the microprecipitation reaction

It allows you to quickly determine the presence of antibodies in the body. But their specificity cannot be determined. Such antibodies can be any proteins formed in large quantities during any infectious processes, immediate or delayed allergic reactions. This means that the true disease can masquerade as a false positive RW and be mistaken for syphilis. On the other hand, venous blood from a finger is not able to detect small concentrations of specific antibodies to the causative agent of syphilis in the initial stages of the disease or during its sluggish course. This causes a false negative result.

Important to remember! The diagnostic value of a finger prick blood test for RW is so low that it makes this method of conducting it impractical in medical practice. More reliable results can only be obtained by examining venous blood. Unlike finger prick analysis, which makes it possible to examine only a small amount of whole capillary blood, plasma can be obtained from venous blood, which contains all the antibodies circulating in the body!

Do not forget about the correctness of the research. It is best to donate blood in the morning or at least on an empty stomach. The day before, strong physical and psycho-emotional stress is excluded. It is advisable to minimize the administration of drugs that affect the activity of the immune response and cause an allergic reaction.

In what cases is it prescribed

The advisability of conducting a blood test for RW has two purposes.

Diagnostic

It involves examining people at risk for developing syphilis or those in whom this disease must be excluded:

• If there are complaints characteristic of sexually transmitted diseases, or unprotected casual sex;
• If there are any manifestations of syphilis;
• During pregnancy. All pregnant women are examined for RV upon registration at the antenatal clinic and again during pregnancy;
• All patients who are hospitalized in medical institutions, especially surgical hospitals;
• All persons undergoing routine medical examinations;
• Medical workers;
• Those in contact with patients with syphilis;
• Drug addicts and HIV patients;
• Persons with prolonged fever and doubts about the reliability of the diagnosis.

A blood test for RW can detect antibodies to Treponema pallidum, the causative agent of syphilis.

Therapeutic purpose

It involves carrying out RW over time for all patients with syphilis. This makes it possible to identify secondary and tertiary forms of syphilis, which are masked under the guise of any diseases of the internal organs. In patients undergoing treatment with an established diagnosis of syphilis, thanks to RW, the dynamics of the process, its activity and the effectiveness of the medications used are determined.

How to properly evaluate the results

Deciphering the results of a blood test for RW can be presented in several ways.

RW negative (normal)

It says that no antibodies to the causative agents of syphilis were found in the blood of the subject. This means that he has nothing to do with this disease.

RW positive

There are 4 degrees of positive reaction, which are indicated by the corresponding number of + signs. The more there are, the greater the likelihood of contracting syphilis. All individuals who are RW positive are subject to re-testing. In patients cured of syphilis, a positive RV in the form of 4 pluses can remain for life.

RW false positive

May be when:

• Active inflammatory process in the lung tissue, including tuberculosis origin;
• Systemic connective tissue diseases;
• Arthritis of various origins;
• After vaccination or infectious diseases;
• In pregnant women;
• Malignant tumors;
• Diabetes mellitus;
• Viral hepatitis and HIV infection.

If there are doubts about the reliability of the results of a blood test for RW, it can be carried out using more modern serological diagnostic methods (blood is taken from a vein for RIF, ELISA), which have higher specificity and reliability.

Important to remember! A negative RW does not provide a 100% guarantee of the absence of syphilis. This is due to the presence of a so-called seronegative window during this disease. This means that from the moment of infection with syphilis, some time must pass for the formation of appropriate antibodies. If blood from a vein, and especially from a finger, is taken during this time period, a false negative result will be obtained!

Blood test RW- This is a serological test for the detection of antibodies to Treponema pallidum. The methodology for conducting this research was proposed by August von Wasserman at the beginning of the 20th century, since then the analysis has been named after him - Wasserman reaction(RW).

Treponema pallidum is the causative agent of syphilis.

Syphilis is a classic disease. Transmitted primarily through sexual contact. You can also become infected through blood. There is a possibility of infection through household means, since Treponema pallidum can be contained in undried saliva and other body secretions.

During the course of the disease, primary, secondary and tertiary syphilis are distinguished.

Primary syphilis is characterized by the appearance of a specific ulcer (chancre) at the site of infection (this can be the genitals, oral or rectal mucosa). A little later, the nearest lymph nodes enlarge - inguinal when the genital organs are affected or submandibular when the oral mucosa is affected. The ulcer heals on its own 3-6 weeks after it appears.

Symptoms of secondary syphilis are observed 4-10 weeks after the onset of the ulcer. This is a pale rash all over the body (including palms and soles), general malaise and (flu-like). Lymph nodes throughout the body enlarge. Then the symptoms disappear, returning from time to time.

Tertiary syphilis is characterized by damage to the nervous system, bones and internal organs. It occurs many years after infection in the absence of proper treatment for the disease.

Thus, a person with syphilis may have long periods during which there are no symptoms. Much depends on the state of the body's immune system. Sometimes, upon contact with an infection, the disease does not develop, but the person becomes a carrier of the infection (the so-called asymptomatic carrier).

In these situations, an RW blood test is the only way to detect the presence of the syphilis pathogen in the body. The analysis also makes it possible to determine how long the carriage of syphilis lasts.

When is an RW blood test necessary?

The RW blood test is a standard procedure to confirm the absence of the syphilis pathogen in the body. It is necessary for everyone whose profession involves contact with people or food - doctors, cosmetologists, hairdressers, cooks, etc. An RW blood test is also one of the mandatory procedures for. It is carried out upon registration and in the third trimester (at the 30th week).

An RW test can also be prescribed when symptoms appear that make one suspect the possibility of syphilis infection:

• rashes on the skin and mucous membranes of unknown origin;
• enlarged lymph nodes (primarily inguinal);
• ulcers on the mucous membrane and discharge from the genitals.

It is recommended to take an RW test if you have casual sexual contact. However, it must be borne in mind that the analysis will be indicative only 5-6 weeks after sexual intercourse. Before that, the analysis may be negative even if infection occurs.

How to donate blood for RW?

The RW blood test should be taken on an empty stomach. For 12 hours before the test, you should not smoke, drink alcohol, take medications, drink juices, tea or coffee. You can only drink water.

Interpretation of RW blood test results

The result of the RW blood test may be:

• negative. This means that antibodies to the causative agent of syphilis have not been detected. In most cases, such a result indicates that there is no Treponema pallidum in the body. However, with primary and tertiary syphilis, there may be cases of negative test results. Therefore, to be sure that you are not a carrier of the disease, the test must be taken several times.
• doubtful (marked with a “+” sign);
• weakly positive (“++”);
• strongly positive (“+++”).

A questionable and weakly positive reaction is also possible in the absence of syphilis infection. Thus, in 1.5% of pregnant women an erroneous weakly positive reaction is detected. A false positive RW result can be observed after passing, as well as in tuberculosis, cancer, and viral hepatitis.

If there is a possibility of a false positive result, the test should be repeated.

What to do if the RW result is positive?

If a positive RW result is obtained upon repeated analysis, the presence of the syphilis pathogen in the body is considered confirmed. In this case, it is necessary to urgently begin treatment.

Syphilis is highly treatable, especially in the early stages. The persistence of the pathogen in the body threatens the transition of the disease to the active stage and the development of manifestations of secondary and tertiary syphilis. The presence of Treponema pallidum in the body of a pregnant woman threatens not only her health, but also the health of the child: infection of the fetus, as a rule, leads to serious developmental disorders. Death is also possible.

Timely detection of syphilis (using special tests) allows doctors to begin treatment on time and prevent the development of dangerous complications of this disease.

Testing for syphilis during pregnancy helps prevent the birth of children with congenital syphilis. Testing for syphilis during pregnancy is described in detail in the article.

Why was I prescribed a test for syphilis?

In the vast majority of cases, doctors do not have the opportunity to obtain accurate data about the sex life of patients (some people hide details of their sex life or underestimate the risk of contracting sexually transmitted diseases). Therefore, in order to protect people from the possible consequences of their own carelessness or lack of medical knowledge, in some cases doctors prescribe so-called syphilis screening tests (that is, tests that are taken by large numbers of people).

Your doctor may order tests for syphilis even if you have no symptoms of the disease and are confident that you could not have contracted it.

The need for these tests is due to the fact that syphilis is sometimes transmitted through everyday contact (not through sexual contact) and occurs in a latent form (that is, without symptoms).

As a rule, a screening examination is prescribed in the following situations:

1. When applying for a job (health care workers, catering workers, military personnel, etc.)
2. When registering for pregnancy.
3. During admission to the hospital, in preparation for operations.
4. Blood donors.
5. Persons imprisoned in places of deprivation of liberty.

Your doctor may also order tests for syphilis:

1. When symptoms of the disease are detected (usually a rash in the genital area).
2. Upon receiving positive results of screening tests for syphilis.
3. If you have had sexual contact with a person who has been diagnosed with syphilis.
4. Newborn children whose mothers have syphilis.

In addition, tests for syphilis are carried out periodically during treatment (to ensure that the treatment is effective) and even after the end of the course of treatment, to monitor cure.

What tests are used to diagnose syphilis?

A dermatovenerologist is involved in the diagnosis and treatment of syphilis. The following tests can be used to diagnose the disease:

Inspection skin, external and internal genital organs is carried out in order to identify the main symptoms of syphilis: chancre, swollen lymph nodes, skin rashes, etc. (see)

In order to detect Treponema pallidum, doctors examine smears (or scrapings) obtained from ulcers, lymph nodes, amniotic fluid in pregnant women, etc. under a microscope. Blood is not examined under a microscope.

Important: If Treponema pallidum was detected in your tests under a microscope, this means that you definitely have syphilis. But if tests show that the causative agent of syphilis has not been detected, you cannot be completely sure that there is no syphilis. To make sure that you are not sick, you need to take additional tests, described below.

PCR (polymerase chain reaction) is a complex and expensive method for diagnosing syphilis, which makes it possible to detect Treponema pallidum DNA in the blood or other test materials (amniotic fluid, cerebrospinal fluid). If the PCR test gives a negative result, then most likely you do not have syphilis. However, if you receive a positive result (that is, if the PCR detected Treponema pallidum DNA in the blood), there is no 100% guarantee that you are sick. This is due to the fact that PCR sometimes gives false positive results (gives a positive result in the absence of the disease). Therefore, if PCR gives a positive result, it is recommended to additionally undergo other methods of examination for syphilis (for example, the immunofluorescence reaction (RIF) and the passive hemagglutination test (RPHA)).

What is a serological test for syphilis?

Serological analysis is the detection in the blood of special proteins (antibodies) that are produced in the human body in response to infection. Unlike previous diagnostic methods, serological tests do not detect Treponema pallidum itself, but only its “traces” in the body.

If antibodies to Treponema pallidum are detected in your blood, this indicates that you are either currently infected with syphilis or have had it previously.

What tests indicate that a person has syphilis?

Serological tests for syphilis are divided into 2 large groups: nonspecific and specific tests. The main difference between these tests is that nonspecific tests show a positive result only if a person currently has syphilis and become negative after treatment, while specific tests remain positive even after the disease is cured.

In other words, a negative nonspecific test result is some guarantee that you are healthy.

What tests for syphilis are nonspecific (non-treponemal)?

Nonspecific tests include the microprecipitation reaction (MR) and the Wasserman reaction (RW). These tests are used to screen for syphilis. After syphilis is cured, these tests become negative in 90% of people.

How these tests work: As a result of the vital activity of Treponema pallidum (with syphilis), cells in the body die. In response to cell destruction, the immune system produces special proteins (antibodies, or immunoglobulins). Nonspecific tests are aimed at identifying these antibodies, as well as calculating their concentration (determining antibody titer).

Precipitation microreaction (MR) and its analogues in some countries: rapid reagin test (RPR, Rapid Plasma Reagins) And VDRL test (Venereal Diseases Research Laboratory) are non-treponemal tests that are prescribed to screen for syphilis.

What will be examined:

usually 4-5 weeks after infection.

if the test shows a positive result, then there is a possibility that you have syphilis. Because this test may falsely give positive results, it is recommended that you undergo additional testing using the specific tests described below. A negative result indicates the absence of syphilis, or an early stage of the disease (before the appearance of antibodies in the blood).

if antibodies are found in the blood in a titer of 1:2 to 1:320 or higher, this means that you are infected with syphilis. With late syphilis, the antibody titer may be low (which is assessed as a questionable result).

False-positive MR results occur in approximately 2-5% of cases, here are their possible causes:

1. Systemic connective tissue diseases (systemic lupus erythematosus, scleroderma, rheumatoid arthritis, dermatomyositis, vasculitis, etc.)
2. Infectious diseases: viral hepatitis, infectious mononucleosis, tuberculosis, some intestinal infections, etc.
3. Inflammatory heart diseases (endocarditis, myocarditis).
4. Diabetes .
5. Pregnancy.
6. Recent vaccination (vaccination).
7. Use of alcohol, drugs, etc.
8. Previously suffered and cured syphilis (in about 10% of people who have undergone treatment, the MR test may remain positive for life).

What could be the reasons for false negative results: the test may erroneously show a negative result if the blood contains a lot of antibodies, if the test is taken at an early stage of the disease before antibodies appear, or with late syphilis, when there are few antibodies left in the blood.

Wasserman reaction (RW, RW) is a non-treponemal test that is used to screen for syphilis in the CIS countries.

What will be examined: blood (from a finger or from a vein), cerebrospinal fluid.

How long after infection does the test become positive? usually 6-8 weeks after infection.

How to evaluate the analysis results:“-” is a negative reaction, “+” or “++” is a weakly positive reaction, “+++” is a positive reaction, “++++” is a strongly positive reaction. If the Wasserman reaction showed at least one plus, then you need to take additional tests for syphilis. A negative reaction is not a guarantee that you are healthy.

How to evaluate the resulting antibody titer: An antibody titer from 1:2 to 1:800 indicates the presence of syphilis.

What could be the reasons for false positive results: The Wasserman reaction can erroneously give a positive result for the same reasons as the microprecipitation reaction (MR), and also if, shortly before donating blood for analysis, you drank alcohol or ate fatty foods.

Due to the large number of erroneous results, the Wasserman reaction (RW, RW) is used less and less and is being replaced by other, more reliable diagnostic methods.

Nonspecific tests (precipitation microreaction (MR) and Wasserman reaction (RW, RW)) are good methods for diagnosing syphilis. A negative test result most likely indicates that you are healthy. But if positive results of these tests are obtained, additional examination is necessary using specific (treponemal) tests.

What tests for syphilis are specific (treponemal)?

Treponemal tests include the following tests: immunofluorescence reaction (RIF), immunoblotting, passive agglutination reaction (RPGA), pallidum pallidum immobilization reaction (TPI), enzyme-linked immunosorbent assay (ELISA).

Specific tests are prescribed for people who have positive microprecipitation reaction (MR) or Wasserman reaction (WR) results. Specific tests remain positive long after syphilis has been cured.

How these tests work: When syphilis pathogens enter the body, the immune system produces antibodies aimed at combating treponema pallidum. These antibodies do not appear in the blood immediately after infection, but only several weeks later. Around the end of the second week after infection, IgM antibodies appear in the blood. Antibodies of this class indicate recent infection with syphilis, but without treatment they remain in the blood for several months and even years (while their number gradually decreases). 4-5 weeks after infection with syphilis, antibodies of another class, IgG, begin to be detected in the blood. Antibodies of this type remain in the blood for many years (sometimes throughout life). Treponema tests can detect the presence of antibodies (IgM and IgG) in the blood aimed at combating Treponema pallidum.

Immunofluorescence reaction (RIF) or Fluorescent Treponemal Antibody (FTA, and its variant FTA-ABS) is a treponemal test that is used to confirm the diagnosis of syphilis in the earliest stages (even before the first symptoms appear).

What will be examined: blood from a vein or finger.

How long after infection does the test become positive?: usually after 6-9 weeks.

How to evaluate the analysis results: The analysis results are presented in the form of minus or pluses (from one to four). If the test shows a minus sign, it means no antibodies were detected and you are healthy. The presence of one plus or more indicates the presence of syphilis.

What could be the reasons for false positive results: False-positive results are rare, but errors are possible in people with connective tissue diseases (systemic lupus erythematosus, dermatomyositis, etc.), in pregnant women, etc.

Passive agglutination reaction (RPGA), or Treponema pallidum hemagglution assay (TPHA) is a specific test that is used to confirm the diagnosis of syphilis at almost any stage.

What is being examined?: blood from a vein or finger.

How long after infection does the test become positive? usually within 4 weeks.

How to evaluate the analysis results: a positive RPGA result indicates that you have syphilis, or are healthy, but have had this disease in the past.

How to evaluate the resulting antibody titer: Depending on the antibody titer, one can roughly assume the duration of infection with syphilis. Soon after the first entry of treponema into the body, the antibody titer is usually less than 1:320. The higher the antibody titer, the more time has passed since infection.

Enzyme-linked immunosorbent assay (ELISA), or Enzyme ImmunoAssay (EIA), or ELISA (Enzyme Linked ImmunoSorbent Assay) is a treponemal test that is used to confirm the diagnosis and determine the stage of syphilis.

What will be examined: blood from a vein or finger.

How long after infection does the test become positive? already 3 weeks after infection.

How to evaluate the analysis results: a positive ELISA result indicates that you have syphilis or have previously had this disease. This test may remain positive even after treatment.

Determining the duration of syphilis infection using ELISA: Depending on what classes of antibodies (IgA, IgM, IgG) are found in the blood, we can assume how long ago the infection was.

			What does this mean
			Recent infection. Less than 2 weeks have passed since infection with syphilis.
			Recent infection. Less than 4 weeks have passed since infection with syphilis.
			More than 4 weeks have passed since the moment of infection with syphilis.
			The infection was a long time ago, or syphilis was successfully treated.

Treponema pallidum immobilization reaction (TPI) is a highly sensitive treponemal test that is used only in cases of questionable results of other serological tests, if false positive results are suspected (in pregnant women, people with connective tissue diseases, etc.) RIBT becomes positive only 12 weeks after infection.

Immunoblotting (Western Blot)– a highly sensitive treponemal test that is used in the diagnosis of congenital syphilis in newborns. This test is used when other tests give questionable results.

What do the results of serological tests for syphilis mean?

The diagnosis of syphilis is never made based on the results of one test, since there is always the possibility that the result was erroneous. In order to get an accurate diagnosis, doctors evaluate the results of several tests at once. Typically, this is one nonspecific test and two specific ones.

Most often, 3 serological tests are used in the diagnosis of syphilis: microprecipitation reaction (MR), immunofluorescence reaction (RIF) and passive hemagglutination reaction (RPHA). The above tests often give opposite results, so we will look at what different combinations of results mean:

		RPGA	What does this mean
			False-positive result of microprecipitation reaction (MR). Syphilis has not been confirmed.
			Syphilis at an early stage (primary syphilis). It is also possible that MR and RIF gave false positive results.
			Syphilis at any stage, or recently treated syphilis.
			Syphilis at an early stage, or a false positive RIF result.
			Long-term and cured syphilis, or a false positive result of RPGA.
			Long-term and cured syphilis, or late syphilis.
			The diagnosis of syphilis has not been confirmed, or the early stage of development of syphilis before antibodies appear in the blood.

Diagnosis of syphilis: answers to frequently asked questions

1. I have never had symptoms of syphilis, but tests showed positive results. What to do?

First of all, you need to find out from your doctor exactly which tests showed a positive result for syphilis. If this is one of the screening tests (microprecipitation reaction (MR) or Wasserman reaction (RW, RW)), then it is possible that the results are false positive. In this case, it is recommended to undergo treponemal tests for syphilis (RIF, ELISA, RPGA). If they give a positive result, then you probably have latent syphilis, which is asymptomatic. You will be asked to undergo standard treatment for latent syphilis. (see Treatment of Syphilis)

If the treponemal tests give a negative result, then the screening tests were incorrect. In this case, it is recommended to consult a doctor who can help determine the cause of false positive results.

It is important to understand that the diagnosis of syphilis is not made by a positive result of one test. To clarify the diagnosis, a complete examination is necessary, the plan of which will be communicated by your attending physician.

2. Can I infect my partner if I test positive for syphilis?

If tests show that you have syphilis, you can infect your sexual partner. It is believed that with one single unprotected sexual contact with a person with syphilis, the risk of infection is about 30%. However, with regular sexual activity this risk is slightly higher.

Therefore, you need to inform your sexual partner that he may be infected with syphilis and that he needs to get tested.

It is important to understand that syphilis can occur in a latent form for a long time, and if you do not inform your partner about the risk of infection, he may find out about the presence of this disease when complications develop, when it is too late.

3. Why are my test results for syphilis positive, but my partner’s test results are negative?

There are several possible reasons:

1. Your partner has not contracted syphilis. The risk of transmitting syphilis during a single unprotected sexual encounter is about 30%. With regular unprotected sex life, this risk is 75-80%. Thus, some people may be immune to this infection and remain healthy even with regular contact with someone with syphilis.
2. Your partner contracted syphilis, but this happened less than 3 months ago, and his body has not yet had time to produce antibodies indicating the presence of the disease.

Thus, if you have a confirmed diagnosis of syphilis, but your partner tests negative, it is recommended that he be tested again in a few months, or take a course of preventive treatment.

4. How long after a course of treatment can I be tested for syphilis again?

5. What test results for syphilis confirm complete cure and are grounds for deregistration?

To monitor the cure of syphilis, non-treponemal tests are used (which allow you to determine the titer of antibodies in the blood): microprecipitation reaction (MR) or Wasserman reaction (RW, RW).

Deregistration is subject to receipt of 3 negative test results carried out at an interval of 3 months (that is, this is possible no earlier than 9 months after the end of the course of treatment).

6. Why do test results remain positive after a full course of treatment for syphilis?

All treponemal tests, as a rule, remain positive after completing the full course of treatment for syphilis and recovery. Therefore, these tests are not used to monitor the cure of syphilis.

If, at the end of the course of treatment, non-treponemal tests (Wassermann reaction (RW) and/or microprecipitation reaction (MR)) remain positive, then it is necessary to determine the amount (titer) of antibodies in the blood for 12 months (donate blood for analysis every 3 months) . Based on changes in antibody titer, further tactics are determined:

If the antibody titer has decreased by 4 or more times during the year, then observation is continued for another 6 months. If the titer continues to decrease, then observation is again extended for 6 months. If, 2 years after the end of the course of treatment, test results continue to give questionable or weakly positive results, then they speak of seroresistant syphilis.

If the antibody titer does not decrease or decreases by less than 4 times during the year, then they also speak of seroresistant syphilis.

7. What is sulfur-resistant syphilis and how is it treated?

Seroresistant syphilis is a condition in which, after completing a full course of antibiotic treatment, tests for syphilis (mainly microprecipitation reaction (MP)) remain positive. There are 2 possible causes of syphilis seroresistance:

1. The treatment did not help, and the causative agent of syphilis is still in the body, stimulating the production of antibodies. Treatment of syphilis may be ineffective in the following cases: late detection and initiation of treatment of syphilis, improper treatment, interruptions in the course of treatment, resistance of Treponema pallidum to antibiotics.
2. The treatment helped, but due to disturbances in the immune system, antibodies against Treponema pallidum continue to be produced. The reasons for such violations are not yet known.

If seroresistance is detected, the doctor will first try to find out if Treponema pallidum is still in the body. To do this, the doctor may prescribe additional tests (for example, PCR, enzyme-linked immunosorbent assay (ELISA)). If it turns out that the first course of treatment did not help, and there are still syphilis pathogens in the body, then you will be prescribed a second course of treatment (usually with antibiotics from the penicillin group). If seroresistance is caused by disturbances in the functioning of the immune system, then additional treatment with antibiotics is pointless (since, in fact, syphilis has already been cured).

The purpose of a blood test for syphilis is to identify antibodies that the body could produce to fight its causative agent, Treponema pallidum.

A false positive test for syphilis can occur in cases where the production of antigens occurred for other reasons.

Why does a false positive reaction to syphilis occur?

False-positive syphilis is diagnosed in 10% of cases.

Since a test for syphilis is prescribed not only when a patient has complaints, but during a medical examination, before employment, during pregnancy, before hospitalization, there is a high percentage of infection in people who did not even suspect the presence of such a disease.

To eliminate errors, it is necessary to ensure the reliability of the results obtained.

Positive results for syphilis are divided into two groups: acute and chronic. An acute false-positive result occurs within 6 months of regular testing.

• acute infectious disorders;
• injuries;
• any vaccination 1-7 days before taking the sample;
• acute poisoning.

In the presence of any of the factors in the body, the process of antibody production is activated, which is reflected in the test results.

If there are chronic problems, the test may show erroneous results for 6 months or more.

• connective tissue disorders;
• any form of tuberculosis;
• chronic liver disorders;
• HIV, hepatitis B, C, D, and other viral diseases;
• autoimmune processes in the body.

The result becomes erroneous due to the systematic production of nonspecific antibodies in response to one of the listed disorders.

What to do if false syphilis is detected

To determine whether a test for syphilis may be erroneous, you need to evaluate the presence of other factors in the manifestation of the disease and the likelihood of infection.

Treponema pallidum is a pathogen that is sexually transmitted through the mucous membranes of the genitals, mouth and rectum upon contact with an infected person. Transmission from an infected mother to her child is also possible.

The incubation period during which the disease does not make itself felt is 2-6 weeks. After this, syphilitic ulcers with a dense base are formed at the sites of possible infection.

After 1-2 weeks, the lymph nodes closest to the site of the lesion enlarge and become painful.

When diagnosing false-positive syphilis, you must return to a medical facility. At the same time, inform about all the medications that you took on the eve of the test, chronic and acute diseases.

If you had unprotected sex with an untested partner or you discovered the first signs of the disease, you should tell your doctor about it.

After collecting an anamnesis and conducting an examination, the doctor will prescribe you a series of tests that will allow you to determine the exact result with an error of less than 1%.

Types of tests for syphilis

There are two types of tests: non-treponemal and treponemal. The first option involves the use of artificial analogues of Treponema pallidum; in the second case, real treponemes are used.

Non-treponemal methods

Such techniques are widespread and are most often used in routine medical examinations.

The advantage is low cost, quick results, and the ability to conduct research using standard laboratory equipment.

To carry it out, blood is taken from the patient, and less often, cerebrospinal fluid. Blood can be taken from a finger or a vein. The error in conducting such a study can be up to 7%.

Precipitation microreaction (MR or RMP)

May include two types of syphilis tests RPR and VDRL. As a result of cell breakdown under the influence of treponema, antilipid antibodies are formed.

Lipids can be destroyed under the influence of other disorders, so the degree of error when performing VDRL and RPR is 1-3%.

Treponemal tests

Such studies are not carried out in all clinics and require expensive equipment.

Therefore, they are used when the presence of the disease is suspected based on the results of non-treponemal tests. The error of such studies is less than 1%.

REEF

Allows you to determine antigens and antibodies. To determine the result, the patient donates blood from a finger or vein. As a result, testing also helps determine the stage of the disease.

RPGA

The RPGA test for syphilis allows you to determine the percentage of red blood cell adhesion. The exact result of the passive hemagglutination reaction can be obtained on the 28th day after infection.

ELISA

Enzyme immunoassay determines the presence and stage of the disease based on the level of immunoglobulins of various types.

A positive syphilis ELISA allows you to determine the types of immunoglobulins that are formed after infection for 14 days, 14-28 days, more than 28 days.

PCR

The most accurate test to detect pathogenic DNA. It is used in rare cases, as it requires complex reagents.

The probability of error of the RIF, RPGA, ELISA tests is less than 1%. With PCR, the error can be 0-1%.

Positive result for syphilis in pregnant women

In pregnant women, an erroneous result can be observed in 1.5% of cases when performing non-treponemal tests. Analysis for this type of disease is mandatory throughout pregnancy.

The first test for syphilis is carried out at 12 weeks, then at 30 weeks and before birth. The result may be false due to natural changes in the body, and in particular, immunity to protect the growing fetus.

Therefore, during pregnancy, a repeat test may be prescribed; it is often prescribed even if the first results are negative, if there was a risk factor.

Treponemal tests may also be prescribed, since the effect of the disease on the child’s body is more destructive than antibiotic treatment if the diagnosis is confirmed.

Weak positive test

If the result form you receive contains 1-2 pluses, this may indicate the presence of a small amount of antibodies. These results can occur in several cases:

• unfinished incubation period;
• late form, after 2-4 years;
• residual antibodies after treatment of the disease.

In this case, a repeat check is required after 2 weeks.

How to properly prepare for tests

If an erroneous test for syphilis was performed, you will be given a repeat test. In order for its results to be as accurate as possible, it is necessary to prepare properly.

• Before the analysis, you are allowed to drink only water, eating is prohibited;
• give up alcohol and smoking 1 hour before 24 hours;
• if you are donating blood from a vein, spend 10 minutes at rest before doing so;
• If infectious diseases have worsened, menstruation is occurring, or the patient was exposed to x-rays the day before, a blood test for syphilis is not performed.

There are also a number of drugs on the list of contraindications, so if you are undergoing treatment, tell your doctor about the medications you are taking.

If the disease is confirmed

If, after carrying out several checks, including treponemal tests, the result is positive, it is worth taking a number of measures:

• inform your sexual partner about this, it is necessary that he also undergo examination;
• close relatives must undergo examination;
• it is necessary to carry out preventive treatment of loved ones;
• During the entire course of treatment, it is necessary to issue a sick leave certificate and avoid close contact with other people to avoid transmission of infection;
• At the end of treatment, a certificate is issued, which must be attached to the medical record and provided when conducting tests for antibodies, so that diagnosticians do not have questions about the appearance of antigens in the results.

When making a diagnosis, information is confidential. It is not disclosed when taking sick leave; in all documents issued by the hospital, the name of the disease is encrypted; people who do not have close contact with the patient are not informed about this diagnosis.

After treatment, the patient is completely safe; having syphilis in the past cannot be a reason for denial of employment or the exercise of other human rights.

If the diagnosis is confirmed in the early stages, then the probability of a complete cure is 100%. Treponema pallidum is one of the few, over many years of treating patients with penicillin, that has not developed protection against it.

Therefore, patients are treated with drugs based on penicillin derivatives. If the primary form of the disease occurs, it is necessary to diagnose and treat all sexual partners that the infected person had within 3 months.

Syphilis after treatment of the initial stage does not leave complications. The disease can lead to disability if it is chronic or if there is infection in the womb.