During summer 2014, a total of 89 Vibrio infections were reported in Sweden and Finland, substantially more yearly infections than previously have been reported in northern Europe. Infections were spread across most coastal counties of Sweden and Finland, but unusually, numerous infections were reported in subarctic regions; cases were reported as far north as 65°N, ≈100 miles (160 km) from the Arctic Circle. Most infections were caused by non-O1/O139 V. cholerae (70 cases, corresponding to 77% of the total, all strains were negative for the cholera toxin gene). An extreme heat wave in northern Scandinavia during summer 2014 led to unprecedented high sea surface temperatures, which appear to have been responsible for the emergence of Vibrio bacteria at these latitudes. The emergence of vibriosis in high-latitude regions requires improved diagnostic detection and clinical awareness of these emerging pathogens.

Globally, Vibrio parahaemolyticus is a leading cause of seafood-associated gastroenteritis. Historically, the V. parahaemolyticus serotypes O4:K12 and O4:KUT, which have been shown to be more virulent than other pathogenic V. parahaemolyticus strains, have been unique to the Pacific Northwest region.¹ These strains, which were first identified in the Pacific Northwest in 1988, caused large U.S. outbreaks in 1997 and 2004.² The outbreaks were linked to consumption of Pacific shellfish, but these strains have not been linked to illness or isolated outside the Pacific Northwest until recently.