Just about the only creatures on Earth thriving as a result of climate change are the pests that pose major health risks to people around the world. Bacteria, in particular, are enjoying the upheaval. They’re taking advantage of the cozier climate to expand their reach and infect hundreds of thousands of additional people every year.

In Bangladesh, where temperatures are expected to rise 0.8 degrees Celsius by 2035, a new study suggests that 800,000 additional people will suffer from E. coli-induced diarrhea. By the end of the century, with temperatures 2.1 degrees warmer than today, we can expect 2.2 million additional cases in Bangladesh alone.

“That’s just for one type of E. coli in one country,” Karen Levy, an assistant professor of environmental health at the university’s Rollins School of Public Health, told The Daily Climate.

The global toll of diarrhea is already staggering. Researchers link the annual deaths of more than 750,000 children under the age of 5 to dehydration caused by diarrhea. There are currently 1.6 billion cases of diarrhea globally every year, and this new study is just beginning to help us understand how climate change may boost that figure even higher. “When you multiply a large number [of diarrhea cases] like you have in Bangladesh by even a very small number, you get a large number of additional cases,” Levy said.

The rise in diarrhea cases reflect an overall pattern of increased exposure to E. coli in warmer climates. Since E. coli tends to spread through feces-tainted food or water, it isn’t exactly clear why warmer weather does so much to increase exposure. However, changes in animal and human behavior, like spending more time outside, are likely related to the increase in cases.

The study uses the fact that diarrhea peaks in the summer to provide a benchmark for increased exposure in warmer temperatures. For every 1 degree Celsius the weather warmed, researchers found an 8 percent increase in E. coli-related diarrhea cases.

The study does not address whether the temperature itself causes the increased exposure or potential changes in behavior as a result of seasonal variation in behavior. Farmers may be more susceptible to E. coli during the summer and spring while they are in the fields, so it’s not clear whether slightly hotter temperatures would further their exposure in a substantial way.

The danger posed by diarrhea can often sound foreign to Westerners accustomed to considering the condition little more than an indignity. But the deadly seriousness of the problem underscores the gulf in access to basic sanitation and infrastructure that still separates many regions of the world. Levy’s suggestion: investing in water and sanitation in these vulnerable regions pronto, to avoid needless deaths and illness.