Infections by germs in the Baltic Sea

Rising water temperature of the Baltic Sea increases the risk of infection

07/23/2012

Climate change promotes the spread of infectious bacteria in seawater. As the researchers around Craig Baker-Austin from the Center for Environment, Fisheries and Aquaculture Science in Weymouth (UK) have found, the temperature rise in the Baltic Sea causes a massive increase in bacterial infections with Vibrio vulnificus.

The Baltic Sea is currently experiencing an "unprecedented rate of warming", with the result that infectious bacteria can spread more and more in the Baltic Sea region, report Craig Baker-Austin and colleagues in the journal "Nature Climate Change". With each degree Celsius, which increases the water temperature, the number of infections by Vibrio vulnificus increases by 1.93-fold. "During the extremely warm summer of 1994, 2003 and 2006, a wealth of vibrio-associated wound infections associated with recreational exposure on the Baltic coast were documented, according to one of the findings of the international research team.

High water temperature and low salt content promote bacterial growth
Pathogens such as the Vibrio vulnificus bacteria can spread particularly well at water temperatures above 15 degrees Celsius and a relatively low salt content of the oceans. Both are increasingly present in the Baltic Sea due to climate change. For swimmers on the Baltic coast, therefore, there is an increased health risk, especially in warm summers. If the bacteria get over injuries or food intake in the organism threatening abdominal pain, diarrhea, nausea and vomiting as well as wound infections up to a blood poisoning. In addition, infection with Vibrio vulnificus bacteria through the skin often accompanies a blistering itchy rash.

Significant increases in infections in warm years
The scientists around Craig Baker-Austin analyzed in their study the infections by the so-called water-living bacteria (Vibrio vulnificus) in the Baltic Sea area since 1982 and checked possible connections with the respective water temperature. The result was as clear as it was worrying. The number of infections has increased significantly in the extremely warm summers of 1994, 2003 and 2006. In 2006 alone, 67 infections with Vibrio vulnificus were registered in bathers on the Baltic Sea. Some of them have even died as a result of the infection, write Craig Baker-Austin and colleagues. Media also reported cholera infection by the Baltic Sea.

Per degree Celsius warming doubling of bacterial infections
The prognosis drawn by the scientists based on the climate forecasts up to the year 2050 also shows how rapidly the bacterial load of the Baltic Sea water will continue to rise in the coming years. With each degree Celsius increasing water temperature, the number of infections will almost double. Particularly affected are the more densely populated coasts of the middle and southern Baltic Sea, such as on the coast of eastern Germany, according to the researchers. But even in Denmark, southern Sweden and Poland, the spread of Vibrio vulnificus bacteria will be of concern with increasing water temperature. Ultimately, their study shows for the first time "that climate change is also bringing Vibrio pathogens to temperate regions," write Baker-Austin and colleagues.

Dramatic increase in bacterial infections expected in the Baltic Sea region
As the Baltic Sea is the fastest-warming marine ecosystem worldwide, researchers expect a dramatic increase in infections with Vibrio vulnificus bacteria in the Baltic Sea region in the future. According to Craig Baker-Austin and colleagues, the water temperatures in the Baltic Sea increased by about 1.35 degrees Celsius between 1982 and 2007 - "seven times more than the global average." For the future, a further acceleration of warming is to be expected. Therefore, the experts assume that by the year 2050, the number of Vibrio infections will increase massively. Corresponding infections are then expected in ordinary summers. In addition, according to the statement of the international research team, an expansion of the risk area to the north is to be expected, whereby the inhabitants of metropolitan areas such as Stockholm or St. Petersburg are then endangered by the infectious bacteria. "More than 30 million people are living" in less than 50 kilometers from the Baltic Sea, according to Craig Baker-Austin and colleagues. "They are vulnerable to further warming of the Baltic Sea from infections with Vibrio vulnificus bacteria. (Fp)

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