Climate change could be driving an increase in illnesses such as cholera and gastroenteritis in northern Europe, scientists have warned.A rise in temperatures in the Baltic Sea has triggered the growth of the water-borne bacteria Vibrio.The bacteria, which is passed to humans by eating raw or undercooked shellfish or from exposure to seawater, can cause various infections, ranging from cholera to gastroenteritis-like symptoms.
An international team examined sea surface temperature records and satellite data in the Baltic, as well as statistics on Vibrio cases in the region.The bacteria usually grow in warm and tropical marine environments, and the researchers found the number and distribution of cases in the Baltic Sea area was linked to peaks in sea surface temperatures.
For each year that the temperature rose by one degree, the number of vibrio cases rose by almost 200 per cent.The study focused on the Baltic Sea in particular because it warmed at an unprecedented rate of 0.063 to 0.078 degrees Celsius a year from 1982 to 2010, or 6.3 to 7.8 degrees a century. Study author Craig Baker-Austin from the UK-based Centre for Environment, Fisheries and Aquaculture Science, said: 'The big apparent increases that we've seen in cases during heat wave years... tend to indicate that climate change is indeed driving infections.'
Climate studies suggest that rising greenhouse gas emissions made global average surface temperatures increase by about 0.17 degrees Celsius a decade from 1980 to 2010.'(It) represents, to our knowledge, the fastest warming marine ecosystem examined so far anywhere on Earth,' the paper said.
Many marine bacteria thrive in warm, low-saline sea water. In addition to warming, climate change has caused more frequent and heavier rainfall, which has reduced the salt content of estuaries and coastal wetlands. As ocean temperatures continue to rise and coastal regions in northern regions become less saline, Vibrio bacteria strains will appear in new areas, the scientists said.
Vibrio outbreaks have also appeared in temperate and cold regions in Chile, Peru, Israel, the northwest U.S. Pacific and northwest Spain, and these can be linked to warming patterns, the scientists said. 'Very few studies have looked at the risk of these infections at high latitudes,' Baker-Austin said.
'Certainly the chances of getting a vibrio infection are considered to be relatively low, and more research is focused on areas where these diseases are endemic or at least more common,' he added.Previous Vibrio outbreaks in colder regions have often been put down to a sporadic event or special conditions rather than a response to long-term climate change.
This is because the effects of global warming can be more pronounced at higher latitudes and in areas which lack detailed historical climate data, the study said.Writing in the journal Nature Climate Change the authors, from Britain, Finland, Spain and the U.S., said: 'There is increasing concern regarding the role of climate change in driving bacterial waterborne infectious diseases.' However Baker-Austin added a note of caution saying there are still 'huge data gaps in that area which need addressing.'