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Lambliasis: determination of antibodies to Giardia antigens in blood
Medical expert of the article
Last reviewed: 05.07.2025
Antibodies to Lamblia intestinalis antigens are normally absent in the blood serum.
The causative agent of giardiasis - Lamblia intestinalis ( Giardia lamblia ) belongs to the flagellate type. In the human body, giardia live in the duodenum and jejunum in a vegetative form and as a cyst. Giardiasis occurs everywhere, giardia are detected in 10-12% of the practically healthy adult population and in 50-80% of children. When giardia enter the human body, they multiply in huge quantities and populate the mucous membrane of the duodenum and jejunum, leading to impaired peristalsis, parietal digestion and absorption. Intestinal dysfunction develops (diarrhea, sometimes with an admixture of blood). The bile ducts and gallbladder (cholangitis, cholecystitis), as well as the pancreas, can be involved in the process.
To diagnose giardiasis, feces (detection of cysts and vegetative forms of the pathogen) and bile obtained by duodenal intubation (the frequency of detection of giardia does not exceed 50%) are most often examined. Due to the inconsistent excretion of the parasite with feces, it is necessary to conduct repeated tests. In recent years, test systems based on ELISA have been developed that allow the detection of the surface antigen of giardia cysts in feces. The diagnostic sensitivity of the method is 90%, specificity - 100%. To obtain a positive test result for giardiasis, it is enough to have 10-15 cysts of giardia in the feces. In some cases, false positive test results are possible in the presence of other pathogens of parasitic infections in the feces.
Recently, the ELISA method has been used to diagnose giardiasis, which allows determining the content of specific antibodies to giardia antigens in the patient's blood. Existing ELISA test systems allow for the detection of specific antibodies of different classes (IgM, IgA, IgG) or total antibodies separately. IgM antibodies to giardia antigens are detected in the blood on the 10th-14th day after invasion. Then, IgG antibodies appear and remain at a fairly high level at almost all stages of giardiasis. After complete elimination of the parasite, the level of specific (IgG) and total antibodies decreases sharply within 1-2 months. Antibodies disappear from the blood completely within 2-6 months.
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