implementing quarantines and creating local boards of health. Nevertheless, the public became overwhelmed with fear of the disease and distrustful of authority, primarily doctors. Unbalanced media reports led them to believe that a disproportionate number of people were dying in the hospital. There were speculations that the sick were being killed by doctors to advance medical research. This led to several riots in Liverpool. That same year, cholera reached the Americas.
The third pandemic (1852 - 1859) is believed to have been the deadliest, claiming close to 1.5 million lives. In 1854, following 23,000 deaths in Great Britain, British physician John Snow used methods of mapping and contact tracing to identify the source of a cholera outbreak in the Soho area of London: contaminated water from a public well pump. The number of new cholera cases in the area dramatically declined when the pump was disabled by local officials. Snow's findings inspired changes in the water and waste systems of London and other cities. This was a huge step forward for public health around the world.
The fourth and fifth cholera pandemics, occurring 1863 - 1875 and 1881 - 1896, respectively, were overall less severe than previous pandemics. In 1883, German microbiologist Robert Koch developed a way to grow V. cholerae and show that the presence of the bacteria in the intestines caused cholera. In 1892, a vaccine against cholera was created by Waldemar Haffkine, which he first tested on himself before conducting trials in India.
The sixth cholera outbreak (1899 - 1923) spared Western Europe and North America due to quarantine measures and the progress made in public health and sanitation. By 1923, cholera had dissipated throughout most of the world, except in India where it killed more than half a million people in both 1918 and 1919.