Wednesday, August 19, 2020

The Primary Culprit Spreading Cholera In The Era Of Accelerated Global Warming

Cyclops.jpgImage result for Rita Colwell
Cyclops - the plankton that spreads cholera, and Dr. Rita Colwell, who developed the "cholera paradigm" based on the disease existing in the natural environment.

As Dr. Rita Colwell writes in her summary to her 1996 paper:

"Vibrio cholerae, a marine vibrio, requiring salt for growth, enters into a dormant, viable but nonculturable stage when conditions are unfavorable for growth and reproduction. The association of Vibrio cholerae with plankton, notably copepods, provides further evidence for the environmental origin of cholera, as well as an explanation for the sporadic and erratic occurrence of cholera epidemics. On a global scale, cholera epidemics can now be related to climate and climatic events, such as El NiƱo, as well as the global distribution of the plankton host.."

This paper ('Global Climate and infectious Disease: The Cholera Paradigm') was a blockbuster revelation in 1996, given the warp and woof of the academic research community still wanted to see the disease as a medical problem - something like smallpox.  This as opposed to something existing in the natural environment and spread by natural, water-borne hosts - the copepods - of which the Cyclops plankton is one example (see top image).  So little wonder it took decades for Dr. Colwell's insights to enter the mainstream.

We know now, thanks to Dr. Colwell's work, there is indeed a "cholera paradigm" at work in spreading the disease and we need to be aware of how climate disruptions are facilitating the spread.  This is especially relevant now as much of her recent research has focused on the role of climate change on vibrio cholerae, the bacterium that causes cholera.

Indeed, this work is even more critical now than in 1996 given the degree to which the planet has gotten much warmer and the CO2 concentration now over 415 ppm.   To fix ideas, a year ago Laure Resplandy , a geoscientist at Princeton University led a startling study published  in the journal Nature  observing:

"If you look at the IPCC 1.5C, there are big challenges ahead to keep those targets, and our study suggests it's even harder because we close the window for those lower pathways. A warmer ocean will hold less oxygen, and that has implications for marine ecosystems.  There is also sea level, if you warm the ocean more you will have more thermal expansion and therefore more sea level rise."
The critical element is the fact that as waters get warmer they release more carbon dioxide and oxygen into the air.  The former then reinforces the existing positive feedback mechanics,

In a 2016 study of the North Atlantic and the North Sea over the past half century, Dr. Colwell found that warming sea temperatures appeared to have multiplied vibrio bacteria and escalated cholera outbreaks.  According to her (WSJ, Aug. 14-15, p. C2):

"We documented the first demonstration of increased infection related to climate change."

The prime takeaway?  The disease seems to be spreading north as the more temperate regions also endure more intense warming, including of the oceans.  All of which is also consistent with a Bulletin Of The Atomic Scientists' warning that the existing climate models are understating the warming trends, e.g.

Climate report understates threat


"So far, average temperatures have risen by one degree Celsius. Adding 50 percent more warming to reach 1.5 degrees won’t simply increase impacts by the same percentage—bad as that would be. Instead, it risks setting up feedbacks that could fall like dangerous dominos, fundamentally destabilizing the planet. This is analyzed in a recent study showing that the window to prevent runaway climate change and a “hot house” super-heated planet is closing much faster than previously understood."

The sobering realization from the cholera paradigm is that anywhere on Earth near warming oceans is subject to cholera outbreaks. It isn't just a matter of poor hygiene, but rather of knowing the presence of infected copepods means filtration of water is essential.  This is something the island nations of the Caribbean need to be cognizant of as well.

No comments: