Syphilis test

Syphilis is a sexually transmitted disease that causes a pale spirochete ( Treponema pallidum ). The disease begins with the appearance of a painless ulcer at the site of the pathogen (chancre) and regional lymphadenitis. After a while, the infection becomes generalized: secondary, and then tertiary, syphilis develops. Classification of syphilis is given below.

Classification of syphilis

• Primary - develops in 10-90 days (an average of 21 days) after infection.
• Secondary - develops 2-6 months after infection or at 2-10th week after the appearance of a solid chancre.
• Latent (latent) - the stage of the disease, in which serological reactions are positive, and there are no signs of damage to the skin, mucous membranes and internal organs:
  • early latent - less than 2 years from the onset of the disease;
  • late latent - more than 2 years from the onset of the disease;
  • unspecified latent.
• Tertiary - develops 3-7 years after the onset of the disease (from 2 to 60 years), gums appear after 15 years.
• Congenital.

Analysis for syphilis 

For the diagnosis of syphilis, the most widely used serological methods that allow to detect immune disorders (the emergence of antisyphilitic antibodies) in the body of the patient in response to the multiplication of the causative agent of the disease.

The emergence of antisyphilitic antibodies in the disease occurs in accordance with the general patterns of the immune response: first, the synthesis of antibodies of the IgM class occurs, as the development of the disease, the synthesis of IgG begins to predominate. IgM antibodies appear 2-4 weeks after infection and disappear in untreated patients after about 18 months; when treating early syphilis - after 3-6 months; late - after 1 year. IgG antibodies appear usually at the 4th week after infection and reach higher titers than IgM. They can persist for a long time even after a clinical cure of the patient.

Syphilitic antibodies can be nonspecific (reactive) and specific (anti-treponemal).

For sero-and liquorodiagnosis of syphilis, the following methods are possible.

• The microreaction of precipitation (MR) with cardiolipin antigen is a screening test used in the population screening for syphilis. The MP is performed with plasma or inactivated blood serum. Foreign tests VDRL (VDRL), RPR (RPR) and others are similar to MR, both on the principle of setting the reaction, and on sensitivity and specificity.
• ELISA (use antigen from culture or pathogenic pale treponem).
• Passive hemagglutination reaction (RPHA). Antigens from the culture or pathogenic pale treponem.
• The reaction of immunofluorescence (RIF) in the following modifications: RIF-abs, RIF-c, RIF with capillary blood from the finger.
• A complex of serological reactions to syphilis, consisting of RSK with treponemal and cardiolipin antigen, and MR. Since treponemal antigen is specific, the complex of serological reactions is referred to as diagnostic tests. In connection with the development of more sensitive, specific and less time-consuming reactions, it became possible to replace the DSC with IFA or RPGA (also in combination with MR).
• The reaction of immobilization of pale treponemes, in which pathogenic pale treponema of the Nichols strain is used as an antigen.

[1], [2], [3], [4], [5]