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Opisthorchiasis test: antibodies to the causative agent of opisthorchiasis in blood
Last reviewed: 05.07.2025
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Antibodies to the causative agent of opisthorchiasis are normally absent in the blood serum.
The causative agent of opisthorchiasis is the trematode Opisthorchis felineus. Liver trematodosis occurs at an early stage as an acute allergic disease with high blood eosinophilia, and at a later stage - with predominant damage to the hepatobiliary system, with a moderately elevated or normal eosinophil content. Serological diagnostics (ELISA and RPGA are used) of opisthorchiasis at an early stage of the disease, before the parasite begins to release eggs, is the only method of laboratory diagnostics, and in chronic opisthorchiasis - an auxiliary method.
The sensitivity of the ELISA method for diagnostics of opisthorchiasis in the acute phase approaches 100%, in the chronic phase of the disease - 70%, depending on the intensity of the invasion. IgM antibodies appear in the blood 1 week after infection, reach maximum values 1.5-2 weeks, and after 6-8 weeks their titer begins to rapidly decrease. IgG antibodies begin to be synthesized 2-3 weeks later than IgM antibodies. Their concentration reaches its maximum by the 2-3rd month after infection and can remain at this level for up to 1 year or more. However, with long-term disease, patients often experience a decrease in the titer of specific antibodies below the sensitivity threshold of diagnostic methods due to the binding of antibodies to the helminth antigen and the formation of CIC.
False positive test results are possible when examining the serum of healthy individuals in 1% of cases, patients with non-parasitic diseases (allergies, gastrointestinal pathology, hepatobiliary system, systemic diseases) - in 1.5%, toxoplasmosis - in 5.6%, toxocariasis - in 7.3%, echinococcosis - in 15.4%, trichinosis - in 20.0%, fascioliasis - in 29.4% of cases.
In opisthorchiasis foci, low serological reaction rates are recorded among native residents due to innate tolerance. In the migrant population (for example, shift workers, migrants, etc.), due to the lack of innate immunity to infection with Opisthorchis felineus, high serological reaction rates are usually noted.
In serological diagnostics, it is possible to obtain false negative results against the background of immunodeficiency states due to concomitant chronic diseases or taking medications (antibiotics, glucocorticosteroids, chemotherapy drugs).
Indications for testing for opisthorchiasis:
- high blood eosinophilia or leukemoid reaction of the eosinophilic type in individuals who have eaten river fish;
- examination of individuals who worked or lived in areas endemic for opisthorchiasis and who, at the time of examination, suffered from diseases of the biliary tract.
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