(CNN) -- Cholera is an intestinal infection that's rare in the United States currently. But in the developing world it's a serious problem, with 3 to 5 million cases every year worldwide, according to the World Health Organization. The disease brings on diarrhea, which can kill a person if he or she is not properly hydrated. A tremendous advance in hydration was invented by David Nalin, along with his colleague Richard Cash. Nalin was working in Bangladesh during a cholera epidemic in 1968, when intravenous solutions were the only treatment. He knew that an oral method of rehydration would be much more accessible and cost-effective for the people who needed it most.
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There are 3 to 5 million cases of cholera every year
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It can kill those who aren't properly hydrated
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David Nalin developed the rehydration solution in 1968
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