Blood test for syphilis

Blood testing for syphilis is carried out as part of the screening of the population, it may be required when registering in any medical institution, in a skin and venereal clinic or in a antenatal clinic. When prescribing a laboratory examination for syphilis to a patient, one should not forget that the absolute criterion for making a diagnosis is the direct identification of the causative agent of the disease – treponema pallidum (T. pallidum) or its genetic material.

After infection, the victim begins to pose a significant danger to others. To prevent the worst, appropriate testing is recommended as soon as characteristic symptoms are detected.

Otherwise, the infection will become a provocateur of a deterioration in the general state of health, having a destructive effect on the body’s systems.

Syphilis may be more severe with simultaneous HIV infection; in these cases, ocular involvement, meningitis, and other neurological complications are more common and more severe, and without adequate treatment, the prognosis is usually poor.

There are scientific studies on the harmful effects of syphilis on the future offspring of the victim. This is explained by the fact that the infection can affect the genetic apparatus and damage the chromosomes.

The epidemiological situation continues to be tense: latent forms prevail in the structure of syphilis, the number of late forms of infection is growing, which dictates the need to strengthen epidemiological control over the spread of the disease and the widespread use of specific methods of laboratory diagnosis of syphilis.

Blood test

The first serological reaction for diagnosing syphilis was the complement fixation reaction proposed in 1906 by Wasserman, Neisser and Brook. However, at present this method, which at one time became revolutionary and laid the foundation for the serological diagnosis of syphilis, is considered obsolete: it is performed for a long time, subjectively interpreted , often gives false negative and false positive results and is not subject to standardization. Depending on the stage of the disease, subsequent therapy is determined, but specific methods for the laboratory diagnosis of syphilis are necessary to establish the stage.

Thus, in primary syphilis, after an incubation period of 3–4 weeks (range 1–13 weeks), the main lesion (chancre) develops at the site of entry. The initial red papule quickly forms a hard chancre, usually a painless sore with a firm base; when rubbed, a clear liquid flows out, containing many spirochetes. Nearby lymph nodes may be enlarged, firm, and painless.

About half of infected women and a third of infected men are unaware of the presence of a chancre because it rarely causes symptoms. Chancres in the rectum or mouth tend to occur in men and often go unnoticed. The chancre usually heals in 3-12 weeks. After that, people look completely healthy, but are a source of infection. Diagnosing the disease at the initial stage of the lesion will allow achieving the highest productivity of the subsequent therapy program. But if the primary alarming symptoms are ignored, secondary syphilis develops.

It is characterized by the appearance of a special skin rash, the so-called syphilitic dermatitis is usually symmetrical and more pronounced on the palms and soles of the feet. Individual lesions are round, often scaly, and may coalesce, resulting in larger lesions, but they usually do not itch or cause pain. After the lesions disappear, these areas may be lighter or darker than normal. If the scalp is affected, there is often focal alopecia. There are also hypertrophic, flattened, dark pink or gray papules in mucocutaneous areas and moist areas on the skin (eg, perianal, under the breasts); lesions are highly contagious. Lesions to the mouth, throat, larynx, penis, vulva, or rectum are usually round, raised-edged, and often gray-white with a red border. Therefore, the victim becomes highly contagious, posing a significant threat to others. Secondary syphilis can affect many other organs.

The latent stage of syphilis is considered separately, which may be early (less than 1 year after infection) or late (more than one year after infection). They can be detected by detecting antibodies with specific laboratory tests. But an asymptomatic course does not mean that the victim has ceased to be contagious. Especially dangerous is the possibility of transmission of infection from mother to fetus.

The late or tertiary stage develops in about one-third of untreated people, but not until years to decades after the initial infection. Includes severe skin lesions, destruction of the brain, bones and internal organs.

The basis for modern tactics of examination of the alleged patient is not only examination and anamnesis. Today, the main tool in establishing an accurate diagnosis are diagnostic serological tests for syphilis.

We are talking about the detection of antitreponemal antibodies of the IgG and IgM classes. Treponemal tests are qualitative, very specific for syphilis, and include:

• fluorescent analysis for the absorption of treponemal antibodies;
• microhemagglutination test for antibodies to T. pallidum;
• passive hemagglutination reaction with T. pallidum;
• enzyme immunoassay for the determination of T. pallidum (ELISA);
• immunochemiluminescent assay (ICLA).

The second approach (non-treponemal, reaginic analysis) involves the detection of reagin (human antibodies that bind to lipids) using lipid antigens (bovine heart cardiolipin). The anticardiolipin test is a sensitive, simple and inexpensive reagin test that is used for screening but is not completely specific for syphilis. Results can be reported qualitatively (eg reactive, slightly reactive, borderline or non-reactive) and quantitatively as titers (eg positive in a 1:16 dilution). Neither a reaginal nor a treponemal test will be positive until 3 to 6 weeks after the initial infection. Thus, a negative result is common in early primary syphilis and does not rule out syphilis until after 6 weeks. After effective treatment, reagin antibody titers typically decrease by at least 4-fold, becoming negative by 1 year in primary syphilis and by 2 years in secondary syphilis, however, low titers (≤ 1:8) may persist in about 15% of patients. Treponemal tests usually remain positive for many decades despite effective treatment and thus cannot be used to evaluate efficacy. The choice of tests and the interpretation of their results depend on various factors, including possible infection and test results, and whether it is re-infection. Reagin tests are performed in patients who have previously had syphilis. An increase in titer by 4 times indicates a new infection or unsuccessful treatment. Treponemal and reagin tests are performed if patients have not previously had syphilis. The test results determine the following steps:

• Positive results in both tests: these results are indicative of a new infection;
• Positive treponemal test but negative reagin test: A second treponemal test is done to confirm its positive result. Treatment is not indicated if the results of the reagin test are repeatedly negative;
• Positive treponemal test, negative reagin test, but history of recent infection confirmed: repeat reagin test 2 to 4 weeks after infection to see if any new infection is detected.

Features of the study

Depending on the chosen method of analysis, its pricing policy will fluctuate. When screening in a dispensary, the price is usually determined by the cost of a syringe for sampling biological material. However, modern studies in private centers, or assessment of the patient’s condition through innovative techniques, can be an order of magnitude more expensive. Therefore, it is better to find out exactly how much manipulation costs in advance.

When determining the pathogen, as well as the stage of development of the lesion in the reagin and treponemal test, the detection of antibodies will be effective only after at least three to five weeks after unprotected intercourse.

Otherwise, it is impossible to obtain a clear clinical picture. This is due to the timing of the formation of a syphilitic ulcer, at the site of penetration of the infection into the body.

Therefore, the use of a rapid test at an earlier date for a preliminary assessment will only end up being a waste of money.

Blood for analysis is taken from a large vein in the area of ​​​​the elbow bend.

Sometimes a bruise then forms at the injection site, or in the process of collecting material, a person experiences a sensation similar to a burning sensation. But such phenomena are a completely normal reaction of the body to external interference.

According to the protocol, the victim donates blood for analysis on an empty stomach. This means that the last meal should be taken at least eight hours before the procedure in order to avoid the dissolved fatty components of the food taken into the body fluid.

In order not to redo everything anew due to one’s own inattention, the preparation must be carried out especially carefully.

Risk groups

Usually everyone is not sent to be tested for syphilis infection. There is a whole list of risk groups who will need to go for diagnostics, as a rule, these are those who have had unprotected sexual contact with an unfamiliar sexual partner.

In addition, there are several categories that need to be examined:

• blood and organ donors;
• pregnant women or those who are planning a pregnancy;
• as a preparatory stage before surgery;
• workers at increased risk of infection.

In the latter case, the rule applies to medical personnel who have to deal with infected patients on a daily basis.

Separately, situations are considered when testing is necessary for newborns due to the fact that the mother was infected at the time of gestation. The analysis will eliminate the risks of possible congenital syphilis.

But most often, diagnosis is necessary for the following symptoms:

• ulcers in the genital area;
• discharge from the genitals;
• skin rash;
• enlarged lymph nodes;
• bone pain.

When fixing at least a few of the signs listed above, it is advisable to seek qualified advice from a narrow-profile doctor.

False results

The choice of tests and the interpretation of their results depend on various factors, including possible infection and test results, and whether it is re-infection. In laboratory diagnostics, there is always a risk of error and it accounts for about 5% of the total number of diagnosed cases.

When fixing a false positive result, it should be borne in mind that various diffuse diseases of the connective tissue can affect the effectiveness. Even classical arthritis of the rheumatoid type can affect the reliability of the information received. The same goes for systemic lupus erythematosus.

Diagnosis is also hindered by diabetes mellitus or a recent vaccination of the patient, a number of severe infectious diseases such as mononucleosis or tuberculosis. Viral hepatitis or heart muscle disease can also affect the quality of the results provided, especially for endocarditis.

People who suffer from alcoholism in the most advanced stages, or who take various drugs, are also at risk of getting an unreliable result.

Situations where false negative values ​​appear are much less common. The reason is most likely too early diagnosis. Sometimes, this result can be seen in patients with late stage syphilis, when the production of antibodies is practically suppressed.

Schematic interpretation

In approximately 90% of all recorded cases, primary syphilis is successfully diagnosed in the standard Wasserman reaction. But only if it is carried out at least from the sixth week after the alleged unprotected sexual contact.

The average reaction provides for the absence of pronounced indicators in the first 15-17 days. But already in the fifth week, about a quarter of the subjects can get a preliminary result. However, it will be more reliable at the end of the eighth week.

At the stage of secondary syphilis, there is no longer any dependence on time intervals. The procedure without significant obstacles will identify pathogens if they are present in the body.

At this stage, diagnosis is carried out on the basis of several serological reactions, which will determine the duration of infection.

Particular attention should be paid to syphilitic infection in the fourth week of the disease, when primary syphiloma appears. At this point, the Wasserman reaction goes from negative to positive, being fixed for the rest of the time, while the stage of secondary fresh and secondary recurrent course passes.

When it comes to the secondary period without treatment, RW is sometimes still able to return to a negative indicator, but with a clinical recurrence of syphilis, it becomes positive again.

Against this background, recommendations are important that the latent period of the disease is extremely insidious and a negative Wasserman reaction does not indicate a final cure. The only positive aspect, subject to previously prescribed and carefully performed treatment, is a favorable prognosis for further rehabilitation.

With regard to active lesions in the tertiary stage, here a positive result can be traced in most of the analyzes performed among patients. But after the extinction of active manifestations at the tertiary stage, the reaction becomes negative.

Such fluctuations sometimes confuse even experienced specialists, so you should not try to decipher the document from the laboratory yourself and trust the recommendations of the attending physician, especially for cases of the seroresistant form. It indicates the ineffectiveness of antisyphilitic therapy and that it is uninformative to check the dynamics in such a situation cyclically.

It is better to focus on a further recovery program, following medical instructions.

After completing the blood sampling procedure, it is recommended to adhere to a balanced diet all day and drink more fluids, exclude alcohol and intense physical activity, you can treat yourself instead to a piece of chocolate and warm tea.

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