Opisthorchiasis is a parasitic disease affecting the liver. The causative agent is the trematode Opisthorchis felineus.

The early stage of the disease manifests itself in the form of acute allergies (skin rashes, itching, stuffy nose, difficulty breathing, etc.).

The late stage of opisthorchiasis is accompanied by damage to the liver and biliary tract.

If the parasite does not secrete eggs that exit through the intestines, the only diagnostic method is to examine the blood serum for the presence of IgM and IgG antibodies.

The sensitivity of such a serological method in the acute phase approaches almost 100%, and in the chronic phase – about 70%, which depends on the number of pathogens and individual characteristics of the body.

The test relates to the serological diagnosis of genital infections.

The test material is blood, in which antibodies to the pathogen are detected.

Antibodies are components of the body's immune system that are produced to destroy a particular foreign protein-antigen.

In this case, the antigen is opisthorchia (Opisthorchis felineus).

There are several types of antibodies:

• IgA
• IgD
• IgE
• IgG
• IgM

However, the immune system cannot always cope with оpisthorchosis, even with very high concentrations of antibodies.

Each of these antibodies has its own function and its own period of occurrence.

IgG class antibodies begin to be synthesized in the body in the third week after infection.

Their level reaches its maximum value after 2-3 months.

During the first year, antibody concentrations may remain at their highest level.

However, during prolonged periods of the disease, there is often a decrease in the number of antibodies due to their binding to the antigen of the pathogen with the formation of circulating immune complexes.

False positive test results are possible for the following diseases:

• Toxoplasmosis – 5,6%
• Toxocarosis – 7.3%
• Echinococcosis – 15.4%
• Trichinosis – 20.0%
• Fascioliasis - 29.4%

Native inhabitants of the zone of hot spot of opisthorchiasis (Ob-Irtysh basin) have low antibody levels due to innate tolerance to the pathogen.