False-positive Wasserman reaction. False-positive HIV test - what are the reasons for obtaining an inaccurate result?

Syphilis is serious illness high degree contagiousness. To identify the disease, blood tests (venous and capillary) are used, and in some cases, cerebrospinal fluid is examined. The interpretation of the syphilis test is carried out by the attending physician. The patient can independently see and understand some of the symbols in the analysis, but the final conclusion about the presence or absence of the disease must be made by a qualified doctor. A false positive or false negative test for syphilis is possible.

When to see a doctor

For a long time there was syphilis dangerous disease, not amenable to treatment. Modern medicine has all the means to completely cure the disease. The earlier the diagnosis is made and the disease is detected, the easier it will be to treat. Syphilis infection occurs not only through sexual contact, but also through sharing the same household items with a sick person ( Toothbrush, towel, kitchen utensils, etc.). Therefore, periodic express blood tests for syphilis are recommended for every person.

When infected, there is an increase lymph nodes V groin area, the appearance of ulcers and skin rashes in the mouth and genital area. If you notice the first symptoms of the disease, you should immediately consult a doctor. The examination can be anonymous with a referral from a gynecologist, urologist, proctologist, venereologist or regular therapist. After passing the test, you should contact your doctor for a transcript of the syphilis test.

Purpose of the examination

Often during medical examinations, the doctor may prescribe many laboratory tests, including . This referral should not be taken as a suspicion of illness. In many areas public life A certificate of absence of disease is required.

Family planning
Registration for the hostel
Access to the workplace for healthcare workers, catering staff, etc.
Organ or blood donation
Patients who are sexually active
Availability clinical symptoms
End of treatment for syphilis

As a rule, one of the nonspecific (non-treponemal) tests is prescribed as a primary study. The reliability of such tests is relatively low and the patient may receive a false positive result. In this case, a repeat study will be prescribed using a specific (treponemal) test. A positive or negative test must be reviewed by the attending physician.

Preparing for the test

Before donating blood from a finger or vein for testing laboratory research It is necessary to adhere to certain rules in order for the analysis to be as reliable as possible. 8-12 hours before blood sampling you should not consume food, tea or coffee. During the day before visiting the laboratory, it is not recommended to eat spicy, fatty, fried, salty or smoked foods. Antibiotics and other medications can also interfere with the test. All substances taken should be reported to your doctor. He may recommend that you refrain from taking the test for 1 or several weeks. A blood sample can be taken in a private laboratory, a district clinic, or you can call a health professional to your home.

In any case, sterile equipment and disposable gloves are used.

A rapid test for syphilis can be done independently at home. Pharmacies offer special tests with detailed instructions in Russian. The test result is known within 10 minutes. One red stripe on the indicator is negative test for syphilis, two lines – positive. The reliability of such tests is not high enough and cannot serve as confirmation of the diagnosis.

How to understand the result of a nonspecific examination

Patients often feel unsure after the test. Donating blood and not being able to decipher syphilis tests yourself is, of course, unpleasant. Deciphering the blood test requires medical education and the appropriate qualifications of the doctor, as well as taking into account all factors influencing the result. Can a patient read the results of their syphilis test themselves? After seeing the laboratory report, you can draw simple conclusions, but the doctor must confirm or refute the diagnosis.

The toluidine red test is not prescribed for diagnosis, but to check the effectiveness of treatment of the disease. the study shows how much the number of antibodies has changed compared to the previous analysis. If the number has decreased, then the treatment is successful. The analysis is carried out several times during the treatment as prescribed by the doctor. 3 months after completion of the procedures, control testing is carried out.

Non-treponemal tests (RSKk, RMP and RPR) are often prescribed during medical examinations and as a rapid diagnosis. There are several notation options as a result of research. Deciphering them is quite simple:

«–» negative result
"+", "1+") or "++", "2+" weakly positive test
“+++”, “3+” or “++++”, “4+” positive test for syphilis

Either result could be a false positive or false negative for syphilis. In the absence of clinical symptoms and random sexual contacts a negative result can be accepted by the doctor as correct. A positive reaction is usually checked using the treponemal test.

Specific Study Results

Treponemal tests are complex and expensive compared to nontreponemal tests. There are several types of tests used to diagnose syphilis: RSCT, RIBT, RIF, RPGA, ELISA and immunoblotting). One of the precise specific studies is RIBT analysis. The test result may be reported by the laboratory as a percentage.

20% corresponds to a negative result (“–”)
21-30% questionable analysis (“++” or “2+”)
31-50% weakly positive (“+++”, “3+”)
51% or more corresponds to a positive result

Immunoblotting is one of the modern and accurate ways to diagnose the disease. Usually prescribed to confirm or refute the results of the first study. The detection of IgG and IgM antibodies in the blood is indicated by stripes. The test results are interpreted in comparison with the non-treponemal test.

If both results are negative, the patient is healthy or the infection is in the first week of development. Both positive results indicate the presence of syphilis or another, possibly autoimmune disease.

A positive immunoblot test after a negative nontreponemal study indicates the presence of syphilis, an autoimmune disease, or cancer.

There may be a positive reaction in pregnant women. A negative immunoblot test after a positive nontreponemal study means the absence of disease.

Reliability of analyzes

There is always a possibility that the test result is incorrect. When decoding tests for syphilis Special attention should be given external factors independent of the patient. The laboratory technician conducting the research or the patient can also make mistakes when they incorrectly prepared for blood sampling or did not provide the doctor with truthful information about themselves. A false positive result is possible under the influence of the following factors:

Diabetes of any type
Presence of drugs in the blood
Alcohol intoxication
Infectious diseases (measles, hepatitis, mononucleosis, etc.)
Benign or malignant neoplasms
Heart diseases
Taking antibiotics or recent vaccination
Autoimmune diseases (lupus erythematosus, rheumatoid arthritis etc.)
Pregnancy
Eating fatty, spicy or salty foods during the day before blood sampling

Depending on the stage of the disease, some tests may not detect the disease. Thus, the Wasserman reaction (RSKt, and RSKk) is carried out only 3-4 weeks after possible infection with a probability of 100%; in the presence of tertiary syphilis, the reliability will be only 75%. To diagnose the early stages of the disease, it is advisable to use an ELISA test. The assay is an enzyme immunoassay with high sensitivity to antibodies. The reliability of the result is close to 100%; a false positive result in the presence of other diseases is excluded.

Negative test results for venereal diseases mean that the person is healthy. Questionable analysis for syphilis will lead to re-examination. If there are factors that could affect the final conclusion, for example, the presence of other diseases, the doctor will change the test parameters. A positive test result for syphilis is not a death sentence or a reason to panic. With the help of medication, the disease can be completely cured. However, it should be remembered that diseases at an early stage are much more treatable.

In contact with

Every year, despite the appearance modern methods treatment The problem with the spread of HIV infection is constantly growing. At the same time, the standard of living in the country began to have an insignificant impact on the likelihood of the disease. Every year a large number of people die from AIDS. Despite the fact that doctors talk about the possibility of significantly prolonging life, in practice this does not always work out. An important point can be called timely detection of the virus when primary symptoms appear. In this case, a person can promptly rebuild his life, give up bad habits and begin to closely monitor your health. If the virus is detected on the second or last stage development of the disease, the likelihood of prolongation of life is very small. This is due to the fact that over several years of its development, strong the immune system, as a result of which diseases that are rarely found in humans begin to develop. At the same time, even common illnesses appear in their most severe form. That is why tests should be carried out in a timely manner, since if the test is positive for HIV, then treatment should be started immediately. However, there are quite common cases in which testing results in a false positive HIV test result. Let's consider all the features of the diagnostics in question.

That is why tests should be carried out in a timely manner, since if the test is positive for HIV, then treatment should be started immediately

First, you need to understand whether there is a difference in HIV infection and AIDS, as well as how they are tested. Let us highlight the following main points:

It is HIV infection that affects the immune system, and AIDS is the final stage of its development.
From the moment of infection to the development of immunodeficiency, several years can pass; with proper treatment, several decades.
The infection itself causes symptoms in the first stage of development, which can be confused with the symptoms of acute respiratory viral infection or flu.

Thus, you can download that a positive or negative result is given to determine HIV infection. As for AIDS, more research is carried out to determine the stage of development of the disease. complex research. That's why positive test to determine HIV becomes the reason for conducting other studies.

Laboratory research

Is it possible to make an error when getting a positive result? Unfortunately, when examining the submitted sample the usual method an error may have been made. Let's look at the features of a false-positive HIV test and the reasons for receiving it.

Quite often, the prerequisites for such a blood study are a routine examination of a donated sample when, for example, diagnosing ARVI or influenza. It is quite rare for people to purposefully go to be tested for HIV infection. Only after donating blood to a test that is designed to determine the infection in question can the possibility of obtaining a false positive result be eliminated.

Like many other viruses, HIV causes a significant increase in the concentration of antibodies in the blood. However, this indicator can indicate many other health problems. If the concentration of antibodies is high, doctors and the patient themselves should be wary, since the cause may still be associated with HIV infection.

Is it possible to make an error when getting a positive result? Unfortunately, when examining a submitted sample using the usual method, an error may be made.

Enough a common question men and women can be told how long they need to wait to get the result and what the deadlines are within which the research must be carried out. Experts point out that the examination of the submitted analysis can be carried out within 5-6 months after its completion. For such a long time, the virus does not disappear from the samples taken. As a rule, studies can be completed within 2-3 weeks.

HIV diagnosis is carried out in two stages:

Immunoblotting method.

The first stage is carried out in order to weed out healthy antibodies from suspicious ones. However, this method is not enough to make a final diagnosis. At this stage, the result may be false positive.

More complex and precise method HIV infection is determined by immunoblotting. It is this method that allows you to get an accurate result that you can rely on when making a diagnosis. The essence of this method is to destroy the virus into antigens, after which a detailed study of the antibodies is carried out. In this case, the erroneous result may be less likely than when performing only the first stage. However, even it does not provide a 100% guarantee of accuracy, since in some cases the information obtained may cause an incorrect diagnosis.

The world practice of determining HIV infection indicates the spread of false positive results. This is due to the fact that many diseases can cause a similar response to testing a donated sample for the presence of HIV infection. In this case, ELISA is done only on the recommendation of a doctor to recreate the general clinical picture. Only with the second method can doctors make a more accurate diagnosis.

Over the years, quite often one could come across a warning that it is at the moment of donating blood that one can become infected with HIV. However, modern precautions, which consist of using only disposable instruments when collecting blood, mean that the likelihood of infection at the time of visiting the hairdresser is much higher. Therefore, you should not be afraid to go and donate blood for this reason.

The peculiarities of the development of HIV infection in the body are determined by the fact that even with the use of modern research methods and equipment, it is not always possible to detect antibodies. This is due to the fact that for each person the stage of virus reproduction occurs differently. Experts point out that when donating blood within less than a month after a possible infection, there is a possibility of receiving a false result: both negative and positive.

How to eliminate the possibility of obtaining a false result from blood tests?

The fact that the result obtained can be both false positive and false negative determines some recommendations for conducting blood tests. As a rule, after receiving the result after the first blood donation, a second, repeat test is also prescribed after some time. Quite often, the reasons for obtaining different results are non-compliance with the rules for submitting a sample. At the same time, the error of the personnel of a medical institution that specializes in determining HIV or AIDS is practically zero.

Immunoblotting is considered a more complex and accurate method for determining HIV infection.

It is worth remembering that before taking tests it is not recommended to eat sour, spicy, fried foods, sparkling mineral water. Regardless of the quantity in which the products in question were consumed, there is a possibility of getting false result. Therefore, when considering whether a laboratory technician may make a mistake when collecting tests, attention should be paid to following the recommendations on what can and cannot be consumed before carrying out the procedure in question.

You can also reduce the likelihood of errors during research by choosing a medical institution that specializes in conducting the research in question. You can be 100% sure of receiving exact result only when conducting repeated studies after six months, since such a long period incubation period HIV infection has not yet been observed.

What is the incubation period and how is it determined?

As the results of many years of research show, at the initial stage of infection in 99% of cases, the virus in question practically does not manifest itself at all. The severity of the virus depends on general condition body and immune system. Moreover, already during the incubation period, the virus can be transmitted, most often, through sexual contact and through the use of the same shaving accessories.

Also, when considering the incubation period, you should pay attention to the following points:

As a rule, the initial ELISA is given after 3-6 months have passed since the possible infection.
In some cases, the virus appears after 2 months have passed from the moment of infection. However, this situation occurs quite rarely.
Primary symptoms may appear much later or be absent altogether.

At the same time, according to appearance It is almost impossible to determine who has HIV infection. Therefore, no matter how good the new sexual partner looks, it is recommended to use contraception, since it significantly reduces the risk of infection, but does not provide a 100% guarantee of protection.

What are the reasons for getting a false positive result?

IN Lately The anonymous method of conducting analysis at home is very popular. However, it is worth considering that in such a case there is Great chance making an error that will lead to a false positive result.

You can reduce the likelihood of receiving a false result by taking tests in qualified laboratories. Experts know how to reduce the probability of error to 0.01%. However, this indicator does not take into account the fact that the result may be affected by a certain patient’s condition, the presence of other hidden infections And chronic diseases.

You can be 100% sure of obtaining an accurate result only if you conduct repeated studies after six months, since such a long incubation period for HIV infection has not yet been observed.

The most common reasons for obtaining a false positive result include:

Presence of other infections.
Quite often it is difficult to accurately determine HIV during pregnancy. At the same time, women who have already given birth several times are at risk.
When donating blood multiple times as a donor.
With the active development of the influenza or herpes virus, both with and without the manifestation of clinical symptoms.
At infectious lesion respiratory systems.
For a disease that leads to a significant increase in blood density.
At primary stage development of autoimmune diseases.
When exposed to herpes and tuberculosis viruses.
With poor blood clotting, which is a genetic disease.
When taking tests at the time of fever, which arose for various reasons.
For arthritis.
Development oncological diseases at various stages.
With a recent organ transplant.
Diseases leading to vascular damage.
When there is a significant increase in antibody levels for an unknown reason.
During development various types sclerosis.
If the test is carried out by a woman at the time of her critical days.
When bilirubin increases.

There are quite a few processes that can cause a false positive result. For example, an allergy in the blood causes the development of antigens that can be recognized as foreign. At the time of pregnancy, diagnosis is complicated due to hormonal imbalance, but this does not occur in all women.

Possible medical mistakes

A false positive result can be obtained due to a medical error. This is the case due to:

Violations of the requirements for transportation conditions of the collected analysis.
The use of incorrect or low-quality sera, which are the basis of the ELISA method.
If the established rules for collecting genetic material are violated.
In case of violation of blood storage rules.

Unfortunately, medical errors are quite common in medical institutions in small cities. In HIV control centers, the likelihood that medical staff will violate the established rules is very small. The likelihood of an error when taking tests in paid medical institutions is also reduced, since a proven fact of making an error, which resulted in moral and material damage to the client, can become the reason for the selection of a license.

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

False positive test syphilis may 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 contact the medical institution. 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 unverified partner or you notice the first signs of the disease, you should inform 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 result, 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 tests for syphilis 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

Most accurate test, allowing the identification of 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 wrong result may be observed in 1.5% of cases when performing non-treponemal tests. Analysis on this type 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 form you receive with the result contains 1-2 pluses, this may indicate the presence of large quantity 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, in mandatory A repeat check is scheduled in 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 they escalate infectious diseases, is menstruating or the patient was exposed to X-ray exposure, 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 register sick leave and avoid close contact with other people to avoid transmission of infection;
Upon completion of treatment, a certificate is issued that must be attached to medical card and provide during antibody examinations 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 by early stages, then the probability of complete recovery 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 who have had infected person within 3 months.

Syphilis after treatment initial stage leaves no complications. The disease can lead to disability if it passes chronic course or there was an infection in the womb.

A person has to take a test to determine syphilis almost more often than anyone else: hiring, medical examinations, preventive examinations, pregnancy. Performing these studies is necessary - they allow you to identify the disease in the early stages, when treatment will be most effective.

The resulting positive result often baffles a person, especially in the absence of any reason. Detection of false-positive syphilis is a fairly common occurrence, and therefore you should not give in to panic ahead of time. According to information from various sources, up to 30% of primary studies may give an incorrect result. There are many reasons for this phenomenon: changes in the state of the body, somatic diseases. To better understand why they appear, it is worth taking a closer look at the research question.

Types of tests for syphilis

Methods clinical trials are rapidly improving every year. With the development of new diagnostic methods, a false positive reaction to syphilis is becoming less common. If necessary, diagnostics may include several different methods– this allows you to get the most reliable result.

Non-treponemal research methods

These techniques are aimed at identifying proteins that are formed as a result of the activity of the pallidum spirochete. They are aimed at identifying “traces” of the pathogen. Such methods have a relatively high percentage of error (up to 10%). Such techniques are nonspecific, but they allow the degree of infection to be determined by the antibody titer.

Wasserman reaction RW

The most common test performed to detect Treponema pallidum is serological test blood. The Wasserman reaction allows you to determine the presence of the disease in just a few minutes. Therefore, this technique is most often used in laboratories - it does not require much time and has a relatively low cost.

The test uses cerebrospinal fluid or blood. The test material can be collected from a finger (if there is only one analysis) or from a vein (if several studies are required). The result of the analysis may be not only a false positive, but also a false negative. It is possible under the following circumstances:

early stage of infection, when the number of treponemes in the body is still low;
a chronic disease in the subsiding stage, when the number of antibodies decreases.

Note! A false negative result occurs extremely rarely, and therefore if there is at least one positive result out of four, it is necessary to undergo additional examination.

Recipitation microreaction (MR)

This research technique is based on the antigen-antibody reaction. It requires a small amount of material to complete. Aimed at identifying antilipid antibodies that are produced during the destruction of treponema cells. Both the patient's blood and cerebrospinal fluid are used for the study.

Because cell destruction can occur in other areas than syphilis, the test is used as a screening test rather than a confirmatory test. There are two analogues of this technique:

Microscopic test (VDRL). Inactivated blood serum is used to perform the analysis. If a lesion is suspected nervous system syphilis, cerebrospinal fluid is used as the test material.
Macroscopic test (RPR). It is considered a rapid diagnostic method. Visual counting of plasma reagins is used.

This reaction if not observed required sterility may show a false positive result. The appearance of such an analysis is also possible with nonspecific tissue damage, which entails the destruction of lipids. If there is a positive result, a mandatory treponemal test is recommended for confirmation.

Treponemal research methods

This category of analysis provides the most accurate data and there are rarely false positive results. Research is aimed at identifying specific proteins that are released by the body in response to infection. These methods have a higher cost, and therefore are used as confirmatory rather than screening ones.

Specific antibodies begin to be produced by the body only a few weeks after infection with treponema. They can persist for a long period after the disease is cured. Therefore, specific tests may show positive results for a long time after remission.

Note! If RW is positive and specific is negative, the study is repeated after a few weeks.

Enzyme immunoassay (ELISA, EIA)

It is based on assessing the level of immunoglobulins of the IgA, IgB and IgM classes. The first two types of proteins are produced in the body already from 2 weeks of infection, and IgM - a month after infection.

The analysis is interpreted based on the ratio of the presence of immunoglobulins:

only IgA was detected – no more than 14 days have passed since infection;
IgA and IgB were detected – infection occurred 14 to 28 days ago;
all three types were detected - syphilis in the body for more than 28 days;
Only IgM was detected - late syphilis.

The presence of IgM may be a sign of already cured syphilis - synthesis immunoglobulins IgM may continue for several months after remission.

Immunofluorescence reaction (RIF, FTA)

Used to confirm infection at the earliest stages. For the study, blood is taken from a finger or vein. The result is similar to the RW analysis, where a minus is indicated, or from 1 to 4 pluses. If there is at least one plus, additional research may be prescribed.

False-positive results when performing RIF are extremely rare - they can occur in pregnant women, as well as in patients with connective tissue diseases.

Passive agglutination test (RPHA, TPHA)

The antibody titer allows you to determine the presence of syphilis and its stage. This technique provides reliable data already from 28 days after infection. Blood from a finger or vein is used for assessment. Increased antibody levels mean more late stage diseases.

The most accurate research methods

Analyzes in this group are highly sensitive, and therefore the error in their results is extremely low. They are distinguished by a higher cost, compared to other methods, and a more complex execution technique.

Polymerase chain reaction (PCR)

PCR analysis is considered one of the most highly accurate. It is aimed at identifying areas of pathogenic DNA in the human body. The method requires specialized equipment and reagents, and therefore is used in rare cases.

Immunoblotting

Combined research method. Aimed at determining immunoglobulins in the patient’s blood serum. The analysis checks for the presence of a complex of antibodies, which is used to establish the diagnosis. This technique uses electrophoresis, which separates immunodeterminants, and an ELISA reaction, which reveals the separated points.

Treponema pallidum immobilization reaction (TPI)

A highly specific test that determines the response of blood serum to Treponema pallidum. It is widely used all over the world because it has a high probability of accurate results. Special antibodies (immunomobilins) in a patient with syphilis can immobilize treponema. In blood healthy person there are no such antibodies. It is on the presence/absence of this ability that the research methodology is based.

RIBT is used to identify those types of syphilis in which the Wasserman reaction gives negative results - damage to the nervous system, internal organs, hidden form diseases. A false positive result is extremely rare in the CIS countries. The cause of its appearance may be sarcoidosis, leprosy.

Causes of false positive results

The Wasserman reaction can determine “acute” and “chronic” false-positive results. Its severity depends on the nature of the changes in the person’s condition. RW can indicate the stage of exacerbation in the following cases:

infectious diseases in the acute stage;
traumatic injuries;
myocardial infarction;
administration of any vaccine several days before the test;
food poisoning.

These conditions are characterized by increased functioning of the immune system, which leads to increased production of antibodies. They are mistakenly recognized in the reaction as antibodies to treponema, and therefore a positive result occurs.

In the presence of chronic pathologies, the immune system produces a large number of nonspecific antibodies that can cause a reaction. In RW, such a condition may show a false positive result. Therefore, it is worth warning your doctor about the following diseases:

chronic pathologies of connective tissues;
tuberculosis;
chronic diseases viral etiology: HIV, hepatitis B, C, D;
chronic liver diseases;
autoimmune pathologies.

With age, redox reactions in the patient's body slow down. Aging tissue can also show a false positive result, and therefore more accurate research methods are prescribed for elderly patients.

Note! At positive reaction Wasserman, additional research is being conducted to provide a more accurate picture.

Recheck

A repeat test is carried out if the results of the screening study are questionable. It is prescribed if there are one or two crosses - such an analysis requires additional verification. The test can give false positive results in several cases:

Early stage of the disease. Before the appearance chancre the amount of immunoglobulins in the body is quite low.
Late stage of the disease. More than 2 years have passed since the infection, and the antibody titer gradually began to decline.

A repeat analysis, which is carried out after 2-3 weeks, shows exactly whether there is a disease. If there is a positive result a second time, additional clarifying techniques are used.

Tests during pregnancy

One of the most unexpected results may be a positive test result for syphilis in pregnant women, especially if the woman has not changed partners. This situation often terrifies expectant mothers, since treponema can negatively affect intrauterine development baby.

A screening test during pregnancy is carried out several times:

upon registration, at 12 weeks;
beginning of the 3rd trimester, at 30 weeks;
before childbirth.

This is the amount of research that is considered minimal. A false positive may occur due to changes in the body that occur during pregnancy. When a woman is pregnant, her immune system produces a large number of antibodies - this is an evolutionary adaptation to protect the baby in the first year of life.

During pregnancy, an additional clarifying analysis is prescribed, which is characterized by greater accuracy. If a control study shows the presence of a pathogen in the body, treatment is required. The effect of therapy on a growing organism is significantly less possible harm from treponema.

How to prepare for tests?

One way to prevent an incorrect result is to prepare for testing. Due to improper preparation, reactions may occur that are accompanied by the production of nonspecific antibodies, which leads to an incorrect result.

The test must be taken on an empty stomach. You can only drink clean water.
A day before blood sampling, you should completely eliminate alcohol - it creates additional stress on the liver, which can lead to a positive result.
It is recommended to avoid consuming fatty and fried food, spicy dishes and a lot of spices.
It is recommended to refrain from smoking at least 60 minutes before the test.
Before drawing blood from a vein, you need to rest for 10-15 minutes in the emergency room.
Women are not recommended to donate blood during menstruation.
Analysis cannot be carried out after x-ray examination, physiotherapeutic procedures.
It is prohibited to donate blood for syphilis during periods of exacerbation of infectious diseases.

Note! If the patient is taking any medications, he should consult a doctor before the test; a break of several days may be required between taking the drugs and the test.

What to do if syphilis is confirmed?

There is no need to worry if you receive an initial screening with positive results. False syphilis is easily determined by repeated testing. If the diagnosis has been confirmed, you need to take measures:

examination of the sexual partner by a dermatovenerologist;
examination of close relatives;
performing preventive treatment to prevent infection in loved ones;
registration of sick leave for the period of treatment - the sick leave does not contain information about the diagnosis, guaranteeing confidentiality;
At the end of the course of treatment, a special certificate is issued - you need to have it with you in order to avoid questions about false positive results in the next few months.

A positive result for syphilis is not always reliable. Therefore, there is no need to worry and it is recommended to wait additional research. Correct treatment, which was started on time, guarantees a quick recovery with a minimum of residual effects.

Serological tests for the detection of syphilis are based on the detection of antibodies that are formed in relation to treponema that has infected the entire body or a specific area of it. Medical studies claim that one in three patients diagnosed false positive syphilis, may not be infected with this disease. Approximately 32% with a “positive” result at first lost their diagnosis after a second laboratory test. This means that thousands of patients could have been subjected to unnecessary treatment if they had not undergone further testing.

In medicine, false-positive syphilis is defined when tests claim the presence of antibodies, but the disease is actually absent. Detection tests of this disease classified according to the type of antigen used. They can be non-treponemal and treponemal. Unfortunately, the blood test is very sensitive to the presence of antibodies in it, so sometimes it gives false information in the presence of other diseases.

When performing nontreponemal tests in there's blood coming out search for antibodies to cardiolipin. This component is the result of tissue destruction, which occurs in many diseases. Its presence does not necessarily indicate the presence of syphilis, but only the process of destruction that has begun in the body. Having received a positive answer, you need to look for the pathogen by conducting repeated testing using the treponemal method, which is very rarely false.

False ELISA is an exceptional phenomenon

False-positive RW tests are well known, while false-positive syphilis ELISA is extremely rare because this test is performed to confirm the diagnosis. Despite the fact that ELISA has a accuracy rate of about 98%, false positive results for syphilis can be obtained if the patient has certain acute or chronic diseases. Among them it is noted mixed disease connective tissue, autoimmune diseases, diabetes, liver cirrhosis due to alcoholism, viral infections and pregnancy. When conducting ELISA studies, the most modern drugs and reagents. This leads to the fact that a false-positive ELISA can be obtained even after the disease has been cured due to the extremely high sensitivity of the reagents.

Reasons for a false positive test

Doctors facing various manifestations diseases indicate biological false prerequisites. A proportion of people who received a false-positive test for syphilis actually had lupus. This group also includes bejel and relapsing fever, leptospirosis, leptospira. However, having received such a conclusion, the doctor cannot immediately determine the presence of the disease, if at the same time external signs are missing. Re-examination is required. The absence of symptoms a second time and a negative result only indicates that the person received an erroneous verdict. All that remains is to find an alternative disease, which for now skillfully hides and does not allow itself to be detected visually.