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Yersiniosis: antibodies to the causative agent of yersiniosis in blood
Last reviewed: 05.07.2025
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The diagnostic titer of antibodies to the causative agent of yersiniosis in the blood serum for RPGA is 1:100 and higher.
The causative agent of yersiniosis is the gram-negative microorganism Yersinia enterocolitica. According to the antigen structure, more than 50 serovars of Yersinia are distinguished. The most important in human pathology are serovars 03, 05, 07, 08, 09. Yersinia enterocolitica is the causative agent of intestinal yersiniosis, which is characterized by predominant damage to the gastrointestinal tract. Since bacteriological diagnostics of yersiniosis is labor-intensive, lengthy and does not always result in the isolation of the pathogen, the main role in laboratory diagnostics belongs to serological methods - RPGA and ELISA. Recently, various PCR test systems have been used to detect the genes that determine the pathogenicity of Yersinia enterocolitica.
Serological diagnostics of yersiniosis is of great importance for confirming not only the clinical diagnosis, but also for determining the etiologic role of the isolated yersinia. The antibody titer increases a week after the onset of clinical symptoms. To diagnose yersiniosis, the Widal reaction is used to test sera taken at the onset of the disease (days 1-3) and again on days 7-10. A titer of more than 1:100 or an increase in the antibody titer by at least 4 times after 7-10 days when studying paired sera is considered diagnostic. A titer of more than 1:100 is detected in most cases of yersiniosis, but a 4-fold increase is rare. A significant increase in the antibody titer is typical on the 2-3 week (usually the peak is recorded on the 2nd week) and a decrease in their level after the 5th week of the disease. Antibodies to Yersinia enterocolitica types 03 and 09 are most often detected. In this regard, commercial diagnostics used in clinical practice allow diagnosing cases of yersiniosis caused only by these serovars, while in many patients other types of yersinia are no less significant. It should be remembered that antibodies in the blood can persist for several years after the disease and can cross-react with Brucella abortus and Rickettsia spp. Titres of 1:50 are found in approximately 1.5% of healthy individuals with no history of infections.
Determination of antibodies to the yersiniosis pathogen is used to diagnose yersiniosis, including bacterial arthritis, Reiter's disease, Behcet's syndrome, and infectious arthropathies.