Cholera
is an infectious disease that spreads in countries without clean drinking water
or adequate sewage disposal. The bacterium causing the disease was identified
in 1884. How it causes disease was discovered almost 100 years later.
A toxin produced by the bacterium changes the G-proteins in cells lining the
intestine. The G-proteins become "stuck" in the activated—or turned on—state.
They can't turn themselves off as they do when normally regulated. The effect
is that water is pumped continuously out of the cells into the intestines, causing
dangerously severe diarrhea.
