Temperature Changes Around the Globe Are Pushing Diseases Into Unexpected New Areas Craig Welch - National Geographic
go to original June 14, 2017

How Global Warming Is Awakening Deadly Diseases (Seeker)

He'd gone for a swim in the Gulf of Mexico, whose warm waters, it turned out, would soon kill him. The 31-year-old man arrived at Parkland Memorial Hospital in Dallas three days after his dip in the Atlantic. Crushing pain was radiating from his new calf tattoo—an image of hands clasping a cross along with the phrase "Jesus is my life." He had a fever, and dangerously low blood pressure. Black blisters appeared around his ankles. His kidneys and lungs began shutting down. Gangrenous tissue splotched his hips and toes. Within two months, he was dead.

The culprit, a meddlesome bacterium called Vibrio vulnificus, occurs naturally in warm ocean water. It can seep into scrapes or fresh wounds, including those from tattoo needlework. Infections like the one that killed this man in 2016 have appeared sporadically for years in warm seas from Texas to Maryland. But as greenhouse gases boost temperatures across the globe, rare pathogens like these from hotter parts of the planet are now creeping toward the poles, creating new risks for people. Deadly warm-water Vibrio illnesses are on the rise, now appearing even near the Arctic Circle.

"We are seeing lots of new hospitable areas opening up for these bacteria," says Craig Baker-Austin, a Vibrio expert who runs the United Kingdom's Centre for Environment, Fisheries and Aquaculture Sciences laboratory in southern England. "Climate change is essentially driving this process, especially warming."

It's no secret that climate change can spread illnesses such as West Nile virus, Zika, and malaria, as rising temperatures push disease-carrying mosquitoes into new places, from the highlands of Ethiopia to the United States. But warm temperatures and shifting weather patterns work in subtle ways, too. Changes in precipitation, wind, or heat are shifting the threat posed by other human illnesses, from cholera to a rare freshwater brain-eating amoeba to rodent-driven infections like hantavirus. And the importance of all these changes are only growing more significant.

"Probably almost everybody is going to feel this at some point in their life," says Stanley Maloy, a microbiologist and dean of the College of Sciences at San Diego State University. "It may be transmission of a mosquito-borne disease in a place it didn't used to be. It may be a simple case of salmonella. But it's going to affect us all."

While much attention has been paid to the direct physical threats from climate change, such as rising seas and searing drought, scientists are really only beginning to understand many of the potential disease implications. In part that's because as complex ecosystems shift in complex ways, the behavior response of the smallest cogs in those systems, such as insects and microbes, will be the hardest to predict.

Evidence suggests, for example, that moisture changes could alter the spread of the soil-borne fungi that give rise to the American Southwest's flu-like valley fever, but scientists can't yet say for sure. Infections that aerosolize, like tuberculosis, can linger longer and perhaps be transported easier in regions of the world projected to become more humid. New research suggests the spread of blood-sucking kissing bugs that contain parasites that carry Chagas Disease may well help that affliction spread into North America. Already millions of people worldwide, mostly in South America, suffer from chronic Chagas, which can lead to life-threatening heart damage and stroke.

But there also are plenty of pathogens whose courses already are being altered by fossil fuel emissions.

Read the rest at National Geographic

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