Why Do Climate Deniers Like Diarrhea?
August 9, 2016
A fair question, I think.
Rising sea surface temperatures in the North Atlantic are likely to be behind a recent surge in cases of diarrheal diseases from marine bacteria in northern Europe and the US east coast, a new study says.
In their analysis that goes back to 1958, the researchers show that levels of Vibrio bacteria – which can cause illness in humans and even death – have been increasing as sea surface temperatures rise.
Further ocean warming as a result of climate change could exacerbate this spread of marine bacteria, the researchers say, potentially bringing more human infections in future.
Some of these bacteria cause sickness in people and animals. Humans pick them up by consuming water or seafood that carries the bacteria, or through cuts in the skin when swimming.
The most well-known Vibrio is cholera, a diarrhoeal disease that can cause severe dehydration and death if not treated.
This study considers other strains of Vibrio bacteria, such as Vibrio vulnificus and Vibrio parahaemolyticus, which cause similar, though usually less severe, symptoms. These types of illness are known collectively as “vibrosis”, which can lead to complications, such as blood poisoning.
Previous research has linked outbreaks of Vibrio infections around the world to warm sea surface temperatures. Warmer conditions mean a longer summer window for Vibrio bacteria to grow and a greater chance of their survival. This conclusion has been reached in studies of Chile, Peru, Israel and the Baltic states.
The new study, just published in Proceedings of the National Academy of Sciences, says that a warming Atlantic Ocean is the main reason for an “unprecedented” number of Vibrio cases in North Atlantic countries in recent years. This includes a spate of cases contracted by swimmers during the European summer heatwave in 2006.
As the North Atlantic has warmed and concentrations of Vibrio bacteria have increased, the number of Vibrio infection cases in northern Europe and the US Atlantic coast have also risen, the paper says.
There could be several reasons for this, the researchers note, such as people being more likely to go out swimming in warm conditions. But the data suggest that the number and spread of Vibrio bacteria in the water is a strong factor.
This means the rising SSTs could be leading to more Vibrio infections in humans, the paper says:“The evidence is strong that ongoing climate change is influencing outbreaks of Vibrio infections on a worldwide scale.”
Therefore, the continued rise in global SSTs in future years may exacerbate the growth and spread of Vibrio bacteria, the researchers conclude.
The study is a “stunning collaboration that integrates major disciplines, including climate, oceanography, microbiology and public health,” says Prof Drew Harvell, a professor in the department of ecology and evolutionary biology at Cornell University, who wasn’t involved in the study. She tells Carbon Brief:“The implications of these finding are that warming events will increase risk to human health from ocean-based Vibrio bacteria.”