Global expansion of Vibrio spp. in hot water

Climate change is a global phenomenon which is affecting marine and terrestrial environments worldwide. According to IPCC global warming defined as an increase in combined surface air and sea surface temperatures averaged over the globe and over a 30-year period reached approximately 1 C (likely between 0.8 and 1.2 C) above pre-industrial levels in 2017, increasing at 0.2 C (likely between 0.1 and 0.3 C) per decade (Allen et al., 2018). The surface of the ocean has warmed about one degree during the last 80 years and the rate of warming in the top 2000 m of the ocean over the past few decades was about 40 percent higher than previously estimated (US EPA, 2016). Recent projections suggest that ocean surface (0–2000 m) is likely to warm by 1546–2170 ZJ relative to 2005–2019, corresponding to 17–26 cm sea-level rise from thermal expansion (Lyu et al., 2021). Changing climatic conditions under such dramatic scenario are becoming increasingly suitable for the transmission of several infectious diseases caused by microbial pathogens, by directly affecting their biological features (e.g., growth, survival, and virulence), reservoirs and vectors, or by favouring their transmission through induced changes in ecosystems and human behaviour (Mora et al., 2022). In aquatic environments bacterial belonging to the Vibrio genus tend to be more common in warmer waters, especially above 17 C, and are particularly sensitive to changing environmental conditions (Vezzulli et al., 2016). This bacterial genus contains more than 100 confirmed species (http://www. bacterio.net/vibrio.html), 12 of which have been demonstrated to cause infections in humans. Vibrio cholerae the causative agent of cholera is by far the most relevant Vibrio species of public health concern accounting for about three million cases of human infections each year, with a case fatality rate of about 2.4% (Ali et al., 2015). However, only O1 and O139 serogroups are associated with epidemic cholera whilst V. cholerae serogroups other than O1 and O139 also designated non-toxigenic V. cholerae (NTVC) are not associated with the cholera disease. Other non-cholera Vibrio species of relevance for human health include Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio alginolyticus. These microorganisms can cause illness that may range in severity from mild (e.g., gastroenteritis, skin wound, etc.) to life-threatening (e.g., necrotizing fasciitis) generally transmitted via ingestion of contaminated water or food or to exposure of skin wounds to aquatic environments and animals (Ceccarelli et al., 2019). Non-cholera vibrios and their associated infections have been reported to increase due to global warming (Baker-Austin et al., 2018; Trinanes & MartinezUrtaza., 2021). In 1989, the Centres for Disease Control and Prevention (CDC) have established COVIS, the Cholera and Other Vibrio Illness Surveillance system, for reporting human infections with pathogenic species of the family Vibrionaceae, which cause vibriosis and cholera (https://www.cdc.gov/vibrio/surveillance.html). According to COVIS the number of Vibrio cases in recent years has been found to increase in parallel with the rise of SST (Newton et al., 2012). A very similar trend has been reported for Europe, especially in the Baltic Sea, in relation to unprecedented rate of warming of this area (Baker-Austin et al., 2016). Overall, Vibrio species have undergone a global expansion over the past few decades reaching new areas of the world that were previously considered adverse for these organisms (Trinanes & Martinez-Urtaza., 2021). Recent projections showed that coastal areas suitable for Vibrio could cover 38,000 km of new coastal areas by 2100 under the most unfavourable climate scenario with an expansion rate of season suitability in these regions of Received: 13 October 2022 Accepted: 9 November 2022