Climate’s Strong Fingerprint In Global Cholera Outbreaks

Climate’s Strong Fingerprint In Global Cholera Outbreaks

Sonia Shah, Yale Environment 360

Since cholera first erupted from India’s Ganges delta in 1817, the bacterial pathogen has swept across the globe in no fewer than seven worldwide pandemics, afflicting hundreds of millions of people and killing more than 70 percent of its victims within hours if left untreated.⁠ The seventh pandemic — the longest one yet — began in Celebes, Indonesia in 1961, and has spread to more than 50 countries and 7 million people.⁠ That pandemic continues to this day, staking its latest beachhead in earthquake-ravaged Haiti, where a cholera epidemic occurred last year after a reported absence of some 100 years.

Historically and in the modern popular imagination, cholera has been considered a disease of filth carried in sewage. And yet, over the past decade, research on cholera’s natural habitat and links to the climate have revealed a revolutionary new understanding of the disease as one shaped just as much by environment, hydrology, and weather patterns as by poor sanitation. And as temperatures continue to rise this century, cholera outbreaks may become increasingly common, with the bacteria growing more rapidly in warmer waters.

The University of Maryland cholera expert Rita Colwell, a former director of the National Science Foundation, pioneered the study of Vibrio cholerae, the bacteria that causes cholera, in the environment. She and Attributing cholera to environmental influences undermines efforts to prevent the disease, some scientists worry. others have discovered the bacteria in water bodies untouched by human waste, its abundance and distribution fluctuating not with levels of contamination, but with sea surface temperature, ocean currents, and weather changes. After several centuries during which cholera’s spread has been attributed solely to human activity, it has been paradigm-shifting research. “Thirty years ago, we were ridiculed to even say that the bacterium existed in the environment,” Colwell says. “But now it is in textbooks. The evidence is so overwhelming, it is understood.”

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