Epidemiological and environmental investigation of the 'big four' species, 1994 to 2021: a Baltic Sea retrospective study.

BackgroundThe genus comprises several bacterial species present in the Baltic Sea region (BSR), which are known to cause human infections.AimTo provide a comprehensive retrospective analysis of -induced infections in the BSR from 1994 to 2021, focusing on the 'big four' species - , non-O1/O139, and - in eight European countries (Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland and Sweden) bordering the Baltic Sea.MethodsOur analysis includes data on infections, species distribution in coastal waters and environmental data received from national health agencies or extracted from scientific literature and online databases. A redundancy analysis was performed to determine the potential impact of several independent variables, such as sea surface temperature, salinity, the number of designated coastal beaches and year, on the infection rate.ResultsFor BSR countries conducting surveillance, we observed an exponential increase in total infections (n = 1,553) across the region over time. In Sweden and Germany, total numbers of spp. and infections caused by and positively correlate with increasing sea surface temperature. Salinity emerged as a critical driver of spp. distribution and abundance. Furthermore, our proposed statistical model reveals 12 to 20 unreported cases in Lithuania and Poland, respectively, countries with no surveillance.ConclusionsThere are discrepancies in surveillance and monitoring among countries, emphasising the need for comprehensive monitoring programmes of these pathogens to protect human health, particularly in the context of climate change.