Cholera is not a big problem in US. Cholera affects the US citizens very rarely. May be a case or two per year. US people take it very offensively to have any preventable health problem to their citizens.
Yes, Cholera can be treated and cured. However there is no vaccination, so even if you are cured, you could catch it again. Cholera is treated by replacing fluids and electrolytes in your body which are lost by diarrhoea. See the related question below for more information.
You will not get the cholera by breathing the cholera bacilli. They can infect the gut only. You may get immunized to cholera. But immunity to cholera is short lasting and is not very effective as well. By injecting dead cholera bacilli you get the immunity for cholera.
People trying to settle in the Western US had to deal with several obstacles. Namely, they had to survive the journey out west. Then, they had to clear land, settle it, and learn to survive on their own in the middle of nowhere.
There is about 60 % mortality associated with untreated cholera epidemic. It is a surprise, how the 40 % of the patients survive. In one epidemic the Ringer's lactate was not available for the treatment and plane saline was used. There was 33 % mortality in that epidemic.
In cholera vaccination you are injected the dead cells of cholera. So you get antibodies to cholera. This vaccine is not very effective. The protection rate is some where 50 to 60 % only. So you can not keep faith on the vaccine for protection from cholera.