How did improved sanitation reduce cholera deaths in Europe during the fifth and sixth pandemics?

During the fifth and sixth cholera pandemics, improved sanitation and the implementation of clean water systems were the primary factors that reduced the severity of the disease in Europe.1

While the fifth pandemic (1881–1896) remained devastating in regions like Russia and the Middle East, its impact in Europe was notably less severe due to these advancements. By the time of the sixth pandemic (1899–1923), western Europe and North America were largely spared from the widespread mortality seen in earlier outbreaks, specifically because of the widespread adoption of improved sanitation and the development of clean water infrastructure. These measures effectively interrupted the transmission of Vibrio cholerae, which had been identified as the causative organism by Robert Koch in 1883. By focusing on the safety of the water supply and the hygienic disposal of human waste, European cities were able to mitigate the risk of infection that had characterized the earlier, more lethal pandemics.123