beloyar | Don't try this at home ;)

cholera pathogen
Robert Koch vs. Maks Pettenkofer
The two scientists conflicted most notably over the subject of cholera. In one specific case, Pettenkofer obtained bouillon laced with a large dose of Vibrio cholerae bacteria from Koch, the proponent of the theory that the bacterium was the sole cause of the disease. He consumed the bouillon in a self-test in the presence of several witnesses on 7 October 1892. He also took bicarbonate of soda to neutralise his stomach acid to counter a suggestion by Koch that the acid could kill the bacteria. He did not contract the disease, nor did he become unwell. This launched a shadow of doubt over Koch veracity about his claims that the Vibrio cholerae bacteria is responsible for causing the cholera disease. But... why? Probable explanation: Vibrio cholerae is a rather fragile and moody bug. For example, it takes over a billion bacteria to guarantee infection. They are also sensitive to stomach acid. It is also known that people may carry the bacteria without cholera symptoms

There is no vaccine so far. There's no immunity after disease either Luckily, the disease can be successfully treated simply by replenishing fluid loss, even without the antibacterial treatment. Of course, the latter is very effective (antibiotics, e.g. tetracycline).