With temperatures increasing, link between cholera and climate has intensified

Published: Monday 30 September 2002

the link between climate and cholera, a serious health problem in many parts of the world, has become stronger in recent decades, shows a recent study conducted by researchers from the University of Michigan, University of Barcelona and the International Centre for Diarrhoeal Disease Research in Bangladesh.

In a previous study, these researchers had found evidence about El Nio Southern Oscillation (enso), a major source of climate variability from year to year, influencing cholera cycles. In that work, they looked only at climate and disease data from Bangladesh for past two decades. In the new research, they compared these results with data from 1893-1920 and 1920-1940 to see whether coupling between climate variability and cholera cycles has become stronger in recent decades. Their study suggests it has. "What is new in this work is not showing that enso plays a role in cholera outbreak, but that the role of enso has intensified," says Mercedes Pascual from the University of Michigan, usa.

Scientists who study climate change predict that enso will become stronger and more variable in coming years under a global warming scenario, so understanding how its connection to human disease changes will be increasingly important. The greater role of enso in cholera dynamics probably reflects known changes in enso itself, the researchers believe. Since the late 1970s, there has been a tendency towards warmer enso events, in conjunction with global warming. Because the disease-causing bacterium lives in brackish water and thrives in warm temperatures, it may be particularly sensitive to climate patterns. According to the researchers, global warming would mean more warm enso and, therefore, more frequent outbreaks of cholera.

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