Analysis of diarrheal diseases in humans caused by Salmonella in Bulgaria

Introduction. The incidence of salmonellosis among people in Bulgaria in recent years has remained relatively high, despite the annual fluctuations. With this work, we aim to clarify the dynamics in the spread of human infections for 2017 -2023 in Bulgaria. Materials and Methods. Data from annual analyses of 3208 Salmonella cultures from patients and contacts of the NRL Enteric Infections, Pathogenic Cocci and Diphtheria" and primary microbiological laboratories in the country were used. Also, data on reported cases of salmonellosis from all 28 Regional Health Administrations, data from the National Centre for Public Health and Analysis and the end annual analyses of communicable diseases in Bulgaria prepared by the Epidemiology Department of the National Centre for Infectious and Parasitic. Results and Discussion. During the study period, a total of 3208 human salmonellosis cases were laboratory confirmed by bacterial culture isolation, of which 1847 were from patients with enterocolitis syndrome and 1361 from infectious carriers. These cultures represent two species of Salmonella enterica and S. bongori, 4 subtypes- enterica; salame; arizonae and diarizonae and 66 Salmonella serotypes. Salmonella Enteritidis was the leading etiological agent in the patients, with a relative share of 47%, followed by Salmonella Typhimurium- 32.8%, 40.5%- monophasic. The third place is held by Salmonella Infantis - 4,85%. The following serotypes were isolated for the first time in our country: Brazzavile; Larochelle; Ndolo; Kuoka; Jerusalem; Vejle and the unique for the world, new serotype- Salmonella 11: z41: enz15. In carriers, in contrast to patients, other serotypes come to the fore- Muenster; Bazenheid; Dublin, etc. The data obtained from the analysis again confirm that the group most affected by Salmonella infections is the group of infants and young children. Salmonella outbreaks in the country have been decreasing dramatically since 2020, in contrast to sporadic cases. In 2018, an outbreak of a serotype rare in the country- London was recorded. Conclusion. From the above data, it is evident that Salmonella infections continue to be a complex public health problem, making it imperative that in the fight to contain them, their aetiological structure is well understood and monitored dynamically.