[Epidemiological characteristics of salmonellosis in New Zagreb during the 1990-2009 period].

In Croatia, salmonellosis is the leading cause of bacterial foodborne diseases. The aim of the study was to determine the incidence of the disease, patient breakdown by age and sex, the most frequently isolated Salmonella serotypes, the length of carriership, and the most frequent source of infection. It was a retrospective analysis, and the sources of data were reports and epidemiological questionnaires administered to those affected with the disease. During the 1990-2009 period, 4492 cases of salmonellosis were reported in the New Zagreb area. The average incidence was 179/100,000. From 2004 onwards, salmonellosis has been on a decrease in Western Europe countries and the USA, whereas in Croatia it is still the leading cause of bacterial food poisoning. The highest incidence is recorded in children up to the age of 1 year (880/100,000), due to low immunity and a lower infective dose. In the observed period (1990-2009), the most frequently isolated serotype was Salmonella enteritidis (84%), followed by Salmonella typhimurium (7%), Salmonella virchow (3%) and Salmonella hadar (2%). There was a slight female predominance (F:M ratio 1.2:1) in salmonellosis cases. All persons affected with the disease are placed under sanitary surveillance including bacteriological control of the stool. Acute carriership was recorded in 2557 (57%) subjects, whereas stool excretion of Salmonella for more than 90 days (chronic carriership) was present in 139 subjects. In nine (0.2%) subjects, chronic carriership was observed for more than a year. During carriership, 22,460 stool samples were examined, i.e. 5 samples per patient on an average. A total of 1033 (23%) subjects were hospitalized for 7 days on an average, whereas 359 persons stayed in day hospital (1-2 days). Out of 3592 (88.4%) subjects with symptoms of the disease reported on their own, Salmonella was detected by the examination of contacts in 413 (9.3%) and carriership proven in 127 (2.3%) subjects examined for sanitary certificate (persons under sanitary surveillance due to the work with food). There were 90% of sporadic cases and 10% of small outbreaks. The most common source of infection were eggs (32%), poultry (10%) and pastry (10%). The outbreaks were mostly confined to the families. Salmonellosis is a major public health and economic problem, as well as an issue pertaining to veterinary and human medicine. The best and most efficient way to prevent the spread of infection by food is reduction of salmonellosis in animal population.