Most of this is stolen from William MacNeill’s Plagues and Peoples.

Cholera seems to have existed in the Ganges delta for a long time, but it only spread to the rest of the world fairly recently. An unusually severe epidemic broke out in 1817: it spread by ship to Sri Lanka, Indonesia, Southeast Asia, China, and Japan between 1820 and 1822. A British expeditionary force brought it southern Arabia in 1821, and from there is filtered down the east coast of Africa. It moved up into the Persian Gulf, reaching Iraq and Iran, then Syria, Anatolia, and the Caspian.

In 1826 a new epidemic moved even further, spread through Europe and North America.

It had been some time since the last outbreaks of bubonic plague, and most of the techniques for limiting its spread had lapsed. Some places still remembered: Marseilles, for example, had experienced a late outbreak of plague in 1721 and annually commemorated it.

Two main factors interfered with an effective policy response to cholera (not counting ever-present human stupidity and obstinacy): bad science and 19th century liberalism.

Scientists at the time had convinced themselves that the germ theory of disease was just wrong. Yellow fever’s decimation of the French force in Haiti made it important, and when yellow fever hit Barcelona in 1822, French scientists were all over it. They concluded that there was no possibility of contact between yellow fever victims in Barcelona, and ruled out contagion. Mosquito transmission didn’t occur to them.

Worse yet, they generalized their error: they concluded that contagion was never the answer, and accepted miasmas as the cause, a theory which is too stupid to be interesting. Sheesh, they taught the kids in medical school that measles wasn’t catching – while ordinary people knew perfectly well that it was. You know, esoteric, non-intuitive truths have a certain appeal – once initiated, you’re no longer one of the rubes. Of course, the simplest and most common way of producing an esoteric truth is to just make it up.

On the other hand, 19th century liberals (somewhat like modern libertarians, but way less crazy) knew that trade and individual freedom were always good things, by definition, so they also opposed quarantines – worse than wrong, old-fashioned ! And more common in southern, Catholic, Europe: enough said! So, between wrong science and classical liberalism, medical reformers spent many years trying to eliminate the reactionary quarantine rules that still existed in Mediterranean ports.

The intellectual tide turned: first heros like John Snow, and Peter Panum, later titans like Pasteur and Koch. Contagionism made a comeback. I am not an expert on that history, but I think that the classical liberals didn’t argue that it would have been better for people to die than survive due to state-imposed public-health methods.