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Heat Sick

Global Warming Likely to Increase Salmonella Infections

By Chris Carroll


Illustration by Kelsey Marotta

Illustration by Kelsey Marotta

Polar bears bereft of ice and tiny tropical islands slowly being swamped are the standard bellwether images of global warming, but UMD researchers have found a less exotic potential effect right in our back yards—and it’s literally sickening.

The study, led by associate professors Amy and Amir Sapkota, spouses and colleagues in the School of Public Health’s Maryland Institute for Applied Environmental Health, shows that one expected result of climate change—more bouts of extreme weather—should significantly increase future rates of salmonella infection.

Already, as their comparison of state public health data and historical weather records shows, salmonella has a field day when temperatures or rainfall are far above historical norms. The resulting fever, diarrhea and other symptoms are particularly dangerous for the very young and very old. The effect should grow more pronounced as extreme weather increases, something the U.N. Intergovernmental Panel on Climate Change calls very likely.

“When we have extreme heat or rainfall, it can enhance bacterial growth in the environment, including bodies of water,” says Amy Sapkota. “People can then be exposed to these bacteria through ingestion or other contact.”

What’s novel about the study, she says, is that it’s the first to show that climate change will particularly impact coastal dwellers. For example, extreme rain raises the risk of salmonella 7.1 percent in coastal areas, while inland counties only see a 3.6 percent bump.

Runoff from flooded septic systems and chicken farms, both of which are abundant in coastal Maryland, as well as more water recreation, could explain the difference.

The current study is Maryland-specific and may provide some guidance to state health officials and lawmakers, Amir Sapkota says. He hopes to broaden the investigation to other states, and perhaps overseas, providing a more nuanced view of the infectious impacts of global warming on different areas.

“The risk is not equally distributed,” he says. “Adaptation strategies at local and national levels need to account for differential burdens of infectious disease associated with climate change.”

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