Waterborne Disease/ Poop Chronicles, Part Two
The cholera epidemic in London in 1854 was raging on, and Queen Victoria had called Dr. John Snow and commanded him to stop the epidemic. But this seemed impossible, since no one at the time understood the germ theory of disease or how diseases spread.
Some strange ideas about how to avoid disease were floating around, as seen in this somewhat exaggerated newspaper cartoon. We can all imagine how scary it must have been to be surrounded by an epidemic and not know how to protect yourself.
But Dr. Snow did something unprecedented—he went into the area of the city where the epidemic was in progress, the neighborhoods around Broad Street, and he interviewed the survivors of the disease as well as the families of the deceased, to gather information about how the victims had lived, looking for clues. [The students can be supplied with this map of London at the time. Discuss with them the symbols on the map, being certain to discuss the pumps that were in use. The picture at the end of this article may be helpful, since not many students have ever used such a pump, but if you show it before the class tries to figure out how to stop the epidemic, it’s a tip-off.]
[At this point, the class can be supplied with information about the victims, in addition to the map, and asked to figure out how to stop the epidemic. This activity is from Project Wet, a wonderful resource for many water-related lessons, and can be found at http://www.rivanna-stormwater.org/bacteria.pdf. When students have figured out how to stop the disease and have discussed the additional question at the Rivanna Stormwater site, continue with the Poop Chronicles lecture.]
After figuring out that the disease was spread through the contaminated well water in the Broad Street pump, Dr. Snow told the authorities how to stop the epidemic: “Remove the pump handle.” Eventually the suggestion was carried out and the epidemic stopped. It was found that “Patient 0”, the source of the disease, lived in a tenement house close to the Broad Street pump, and effluent from the tenement’s privy was leaking into the ground water and contaminating it.
Subsequently the Queen called in Sir Edwin Chadwick, who made some recommendations to improve the health of the people living in London. He designed a house, intended for a single family to live in, which removed their pump at the greatest possible distance from their privy and also supplied more room as well as air circulation and natural light.
And eventually this plan was submitted to the Queen. What does it show? Sewer lines! Even so, when the sewers were put in, they simply drained the sewage to the river. Sewage treatment plants did not come about till later.
[A good extension of this activity would be to investigate some other waterborne diseases (for example, polio virus, giardia, Salmonella typhus), along with a few other contagious diseases. Students could be given pictures of the pathogens that cause the diseases and asked to investigate the symptoms, causes and cures, in addition to prevention. The students could also be given a picture of the body showing different organs and asked to match the pathogens to the organs they infect. And finally, they could sort the pathogens according to which taxonomic kingdom each belongs to.
To emphasize the environmental aspects of waterborne disease, you might show students the form below, which shows a data table for a number of tests that, taken together, comprise a water quality index. Note that one of the tests checks for the presence of coliform bacteria, a family of bacteria always found in sewage.]