Salmonellosis in Poland in 2018 and 2019.

Aim: The aim of this study is to assess the epidemiological situation of salmonellosis in Poland, in 2018 and 2019 compared with previous years.

Material And Methods: The assessment of the epidemiological situation was performed on the basis of data provided to the Department of Epidemiology Infectious Diseases and Surveillance of NIPH NIH - NRI by sanitary-epidemiological stations through the Epidemiological Case Reporting System (SRWE) and the Registry of Epidemic Outbreaks (ROE), as well as on the basis of data from the annual bulletins "Infectious Diseases and Poisonings in Poland" 2018 and 2019 (NIPH NIH - NRI, GIS, Warsaw, 2019 and 2020) and from information received from laboratories of sanitary-epidemiological stations and data from the Demographic Research Department of Statistics Poland (GIS).

Results: In Poland in 2018 a total of 9,957 cases of salmonellosis were reported in the sanitaryepidemiological surveillance, among these infections 9,651 were cases of intestinal salmonellosis, 306 were cases of extraintestinal salmonellosis. The incidence rate for total salmonellosis was 25.9 per 100,000 population, for parenteral salmonellosis alone was 0.80 per 100,000 population. There were 9,370 cases of confirmed and 587 cases of probable salmonellosis registered. Hospital treatment was given to 65% of patients with intestinal salmonellosis and 88.6% of patients with extraintestinal forms of the disease. The increase in salmonellosis cases in 2018 occurred during the summer months with a peak in cases in August. The highest incidence of salmonellosis nationwide was in the Podkarpackie voivodeship 42.2/100,000, the lowest in the Lubuskie voivodeship 9.4/100,000. More cases were registered in urban areas - 5,866 salmonellosis cases. Cases in the age group 0-4 constituted 37.7% of all cases. Among parenteral salmonellosis 64.7% were people over 60 years of age. In ROE system there were 351 food poisoning outbreaks with Salmonella spp. as the etiological agent, mainly Enteritidis serotype. The most frequently isolated serotypes in Poland in 2018 were S. Enteritidis, S. Typhimurium and S. Infantis, the first of which was responsible for 76.3% of all Salmonella infections. There were 1,719 cases registered in which the serotype was not determined, most of them came from the Pomorskie voivodeship. Sanitary-epidemiological stations performed 547,976 bacteriological tests for Salmonella and Shigella, 0.2% of people working in contact with food had a positive result. There were 43 cases imported from abroad. Due to Salmonella infection 4 people died in 2018. In 2019 a total of 9,234 cases of salmonellosis were registered in Poland, including 8,919 food poisoning and 315 parenteral salmonellosis. The incidence for total salmonellosis in Poland was 24.1 per 100,000 population. There were 8,687 confirmed and 547 probable cases of salmonellosis reported. Due to food poisoning 63.1% of patients were hospitalized, while due to parenteral salmonellosis 87.6% of patients were hospitalized. The peak incidence in 2019 occurred in August. The highest incidence per 100,000 population of total salmonellosis by voivodeship was recorded in the Podkarpackie voivodeship 55.1, the lowest in the Zachodniopomorskie voivodeship 8.8. Almost 40% of all salmonellosis cases in the country were among children aged 0-4; as far as parenteral salmonellosis is concerned, the main group of patients 68.6%, were people over 60 years old. Sanitaryepidemiological stations reported in the ROE system 303 outbreaks of food poisoning of salmonellosis etiology. The most commonly isolated serotype in 2019 in Poland was Salmonella Enteritidis 75.6% of all recorded salmonellosis cases, followed by Salmonella Typhimurium 3% and Salmonella Infantis 1%. The serotype was not determined in 1,692 cases, the highest number in the Pomorskie and Kujawsko-Pomorskie voivodeships - 51% of undetermined isolates each. Laboratories of sanitary-epidemiological stations carried out 610,164 bacteriological tests for Salmonella and Shigella. Among people working in contact with food 0.2% had a positive test result. 71 cases of imported intestinal salmonellosis were registered. Nine deaths due to Salmonella infection were reported.

Conclusions: The salmonellosis situation in Poland in 2018 and 2019 remains at a high but stable level. The significant increase in the number of laboratory tests performed for Salmonella in 2018-2019 and the decrease in the number of people refusing the carrier exclusion test, is an important step in the process of enhancing salmonellosis surveillance.