What's the Difference in Susceptibility to Cholera?

What blood type you are can affect the likelihood that you get infected with cholera and how severe the case is once you are infected. In some parts of the world, for example, in the Ganges River Delta, there's a very low prevalence of people who are blood type O. One hypothesis is that this is at least in part because there is selection against this blood type because it's associated with higher risk of severe symptoms.