Screening studies in the diagnosis of chronic carrier of the causative agent of the typhoid fever among residents of different countries

The results of screening studies of chronic carriage of the causative agent of typhoid fever (S. Typhi) among residents of various countries are presented. We studied 810 blood serums, including: 462 from citizens of the Republic of Guinea, 244 from labor migrants who arrived in the Russian Federation from Central Asia, and 104 from residents of St. Petersburg. Antibodies to S. Typhi Vi antigen were determined in the passive hemagglutination reaction as a marker of possible chronic carriage of bacteria. When screening studies of sera of citizens of the Republic of Guinea in 21 (4,5%) cases, a positive result was obtained. The level of antibodies to Vi- antigen above diagnostic was found in 6 (1,3%) sera. In 5 samples, the level of antibodies was 1:80, in one - 1: 160. Positive results in a screening study of the sera of labor migrants were obtained in 24 people. A confirmatory test revealed antibodies to the Vi antigen in the diagnostic titer in 9 sera. Positive results were obtained from 2 (3,64%) citizens of Tajikistan and 7 (4,09%) citizens of Uzbekistan. Antibodies to the S. Typhi Vi antigen were not found in residents of St. Petersburg (citizens of the Russian Federation). A comparable level of possible chronic carriage of typhoid fever was revealed for residents of epidemiologically unfavorable territories (Africa) and labor migrants coming to our country from Central Asia. The chances of the emergence of sources of infection in our country are increasing due to the increase in international contacts, which requires additional preventive measures.

S. Typhi, typhoid fever, chronic bacterial carriage, serum, antibodies, Vi antigen, S. Typhi, screening tests, the reaction of passive hemagglutination