A new study shows extreme weather, ocean changes, and land disruption have already helped spread more than 200 pathogens. That's an extreme case of climate change creating new contact between humans and infectious diseases, but the phenomenon is widespread. Extreme heat waves, for example, can kill off many infectious viruses, bacteria, fungi, and the creatures that spread them. Whatever survives, however, is adapted to extreme heat — including the fever our bodies produce to kill off pathogens. David Ryder/Getty ImagesHumans and their infrastructure are more vulnerable to the devastating impacts of disease when they're compromised by extreme weather.

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