Every day, unless we are in very bad circumstances, we drink water. In today’s America we are lucky to have wide accessibility to what we almost always consider safe drinking water, while for much of the world obtaining clean water is often a struggle. Contaminated water is the transmission pathway for many bacterial, viral, and parasitic diseases including cholera, typhoid fever, hepatitis A, norovirus, polio, and more. Vaccines, like the polio vaccine, and public water and sewer systems have eliminated or greatly reduced most water-borne risks for most people, and cholera has not been epidemic in the U.S. since 1866 due to our government’s delivery of public health measures. However, in parts of the world the seventh cholera pandemic, which started in 1961, still infects about a half-million people annually and is the seventh largest pandemic ever in terms of lives lost, which may be over 9 million and growing, 65 years into the pandemic. We’re generally lucky in America, but not everyone has access to the best public health here, and our systems are vulnerable. For example, at last count, we are experiencing an outbreak of over 11,500 reported cases of cyclosporiasis in the U.S. The story of Snow, cholera, oysters, pandemics, and miasma Today I’m telling the tale of how a great disease detective, John Snow, put the clues together to save perhaps thousands of lives in the 1854 cholera outbreak in London. Snow became the father of epidemiology, the science of disease source detection that has saved millions of lives. And I’ll talk about water-borne disease in America today; oysters, yum or yuck, however you feel; how measles got to be as rare as cholera in America; and that we need to acknowledge, as we face the corruption of our public health systems, funding, and status in the U.S., that we remain susceptible to very bad pandemics. Plus, I’ll reflect on how the rejection of the evidence by the authorities after Snow’s discovery of the source of the 1854 cholera outbreak is similar to today’s rejection in America of science and proven public health measures. It all ties together, believe it or not. Welcome to new subscriber, Ming Yang, Senior Editor for Nature Medicine, and author of the excellent Health Checks on History Substack. Check it out. Londoner Yang knows well the history of the important site we will visit in the podcast today. The first epidemiologist John Snow was born in poverty in a neighborhood close to the river in York, England, the son of a coal yard worker and eldest of nine children. Drinking water in the neighborhood was from wells or the polluted river. The unsanitary conditions he experienced growing up likely informed Snow’s later cholera investigations. Snow’s aptitude for learning won him an apprenticeship with a surgeon-apothecary, giving him five years of clinical training leading to education and certification as a surgeon able to practice medicine. In 1836, Snow entered the University of London to be become an actual doctor. It was there he made his first important epidemiological discovery, although epidemiology had not yet been named as a science. Snow’s first epidemiological discovery (about arsenic, not cholera) While performing post-mortems on dead patients with fellow students, Snow noticed that some of his colleagues were becoming sick. Snow deduced that the arsenic used to preserve many of the bodies was causing the illness and published a paper to that effect. The University discontinued the use of arsenic to preserve corpses for dissection and the medical students stopped getting sick. Snow’s article also caused arsenic to be removed as an ingredient of candles, which burned brighter with some arsenic in the wax but put off toxic fumes. Snow finished his medical degree in 1843 and would thereafter be titled Doctor. A pioneering anesthesiologist Snow is known for his epidemiology, but anesthesiologists know Snow because of his pioneering research to safely administer ether and, later, chloroform. His reputation as London’s top anesthesiologist was solidified when Queen Victoria insisted Snow administer chloroform to her for the birth of the last two of her nine children. But it was Snow’s work on understanding, mapping, and eliminating the source of the cholera outbreak in the Soho section of London in 1854 that is most acclaimed. Cholera came to England from the Ganges delta in India in 1831, starting the first of four English epidemics. In 1848, the second and most fatal cholera epidemic, with over 40,000 deaths, was manifesting itself in London. The prevailing view of scientists at the time was that transmission of cholera was in something called miasma, essentially the bad smell that accompanied unsanitary conditions. Snow understood how respiration worked from his experience with anesthesia and realized that if it cholera was carried in the air, people who worked in the worst smelling places like slaughterhouses and emptying cesspits, would be the most prone to get sick. That wasn’t happening. Snow and others formed the London Epidemiological Society, meeting first in 1850 at the end of the second cholera epidemic. The new Society was committed to understanding not only cholera, its primary motivation, but to working on other diseases, including smallpox and smallpox vaccination, a topic on which it was very influential with the government. For my fellow epidemiologists, it’s worth noting that some members of this new group also belonged to the Statistical Society of London, which had been formed in 1832. So the drive to solve the mystery of cholera gave birth to a whole new science, just in time to address the third epidemic, where its methods would result in the saving of many lives. Epidemiology today employs sophisticated mapping and statistics and toxicological testing. All three of these fundamental techniques were integrated by Snow in two groundbreaking investigations of the third cholera epidemic. Around September 1st, 1854, at word of a sudden outbreak of cholera deaths in the Soho neighborhood where he had his office, Snow leapt into action, quickly obtaining the addresses of the first 83 fatalities, which he went to visit. Snow noticed they were all within a short distance of a communal water pump on what was then called Broad Street. Snow immediately suspected the pump as the source of infection. Porter beer was the Gatorade of 19th century London, except probably better for you The doctor interviewed many of the families of the deceased, finding 61 that had definitely or likely drunk water from the pump. Snow noticed that there were only a few deaths of workers from the brewery near the pump. The brewery owner told Snow that the workers received a daily allotment of porter beer to take home, the low-alcohol dark beer being a popular and safe hydration alternative to the available water. Also, the brewery had its own water well the workers could use. Wait a minute, beer used for hydration? Doesn’t alcohol cause dehydration? Yes, generally, but with the low 2% to 3% alcohol content of the working-class’s porter, the body retains more water than it loses from the diuretic effect of the alcohol. Plus, the hard-working porter drinkers got significant calories from the beer as well as important B-complex vitamins. Adding to Snow’s growing evidence, just around the corner from the pump was a workhouse, a horrible, jail-like, last resort for people who were poor or disabled. Snow found a water well within the workhouse grounds and only five cholera deaths among the 535 workhouse inmates. His Broad Street pump theory was further supported. Snow sought toxicological evidence and had the pump water examined under a microscopic. Flaky organic matter was found, but otherwise the results were inconclusive. Microscopy at the time could not easily see some transparent microbes like the cholera bacterium, Vibrio Cholerae. As it happened, an Italian professor, Filippo Pacini, identified the rod-like bacterium, called a bacillus because of its stick shape, in the 1854 Italian epidemic. But Pacini’s findings were not widely read, including not by the famous German bacteriologist Robert Koch, who went to Egypt during its cholera epidemic in 1883 and identified the Vibrio Cholerae bacillus in corpses. Koch’s widely disseminated findings convinced the scientific world that a bacterium was the agent of cholera and put nails in the coffin, as it were, of the miasma theory. By Snow’s account, three-fourths of the residents quickly fled the neighborhood of the Broad Street pump soon after the onset of the outbreak with its hundreds of deaths. But many remained, and when Snow took his evidence to the local authorities, he managed to convince them to remove the pump handle With no more water flowing, there were no more infections and the worst of the deaths ended within ten days, as those already sick at the time of the handle removal had either died or were destined to survive. Following the Broad Street pump investigation, Snow continued that same year with his second and larger epidemiological study of cholera, which he called the “Grand Experiment.” Snow tallied the cholera deaths in 32 districts of London. The Lambeth Company supplied neighborhoods with water from the Thames above London, and the Southwark and Vauxhall Company supplied water from the Thames below where sewage was discharged in London Snow’s statistics and map showed that the homes and community pumps supplied with water from the upper Thames had a low risk of cholera and few cases, and those supplied with heavily polluted water from the Thames within London had a high risk of cholera and many cases. Unfortunately, even with the additional hard evidence of the second study, the higher authorities and most scientists were still not persuaded to give up their miasma theory. It was not until the fourth and final English epidemic in 1866 that polluted water w