The habitat of Vibrio spp. bacteria is fresh and brackish water with moderate salinity. Non-toxigenic Vibrio cholerae, as well as several human pathogenic non-cholera Vibrio species, including Vibrio alginolyticus, Vibrio parahaemolyticus and Vibrio vulnificus, cause vibriosis after seawater exposure or consumption of contaminated seafood . Clinical manifestations range from mild gastroenteritis and otitis to wound infections that may lead to severe necrotising fasciitis and septicaemia with a potentially fatal outcome [2–5].
The Baltic Sea region is one of the areas where increasing numbers of cases related to Vibrio species causing vibriosis (VCV) have been reported in the last decades . Several studies have shown how the occurrence of heatwaves, which lead to an increase in sea surface temperature, are linked with an increase in the number of reported vibriosis cases [4,7–12]. For instance, the years with an especially warm summer in the Baltic Sea region, 2006, 2010 and particularly 2014 (the warmest year in historical records at the time), were also the years with the largest number of vibriosis cases reported [6,11].
However, there is a notable gap in surveillance data for vibriosis since it is not a notifiable disease in the majority of European countries [1,6]. Therefore, the aim of this multi-country study was to describe the epidemiology of vibriosis cases in countries bordering the North and Baltic Seas area during the exceptionally warm year of 2018 [13,14], in order to investigate the extent of these infections in the study countries, map their genetic diversity, understand the predictors for developing severe vibriosis, and propose recommendations for public health measures.