Parallels

The day before Independence Day, 2012, Mrs. Yvette Ghannam looked in the incubator and pondered the consequences of what she saw.  The bacteriologist of the Greenwich Department of Health Laboratory removed the Petri dishes with the bright purple media and saw- in one of them- the unmistakable metallic sheen of colonies of coliform bacteria.  These are bacteria that, although not necessarily disease-causing themselves, are nonetheless indicative of sewage contamination, potentially containing a whole host of bacteria, parasites and viruses that can cause disease.  This particular test was especially unfortunate because

 it came from the potable water for Island Beach, which was preparing to receive boatloads of holiday makers for the Fourth of July, when the temperature was expected to be in the nineties.

One day in London in 1854, Dr. John Snow looked at the water sample he held and pondered the consequences of what he saw.  The white precipitate that formed when he added the silver nitrate reagent demonstrated the presence of chloride, which in turn suggested that brackish water from the lower Thames estuary, where sewage was dumped, was being distributed from the public pump on Broad Street.  This was located in the center of a neighborhood that was undergoing a severe epidemic of cholera, causing many deaths.  Dr. Snow had the idea of interviewing victims or their families to try to determine if they had anything in common, and he found that they all got their drinking water from the Broad Street Pump.  None of the workers in the neighborhood brewery came down with cholera, as they drank only the beer they themselves brewed. 

Back in Greenwich, Mrs. Ghannam informed the Health Director, Caroline Calderone Baisley, who then had the unpleasant duty of shutting down the water supply at Island Beach until it could be purified.  She ordered warning notices posted and told the snack bar to use bottled water for food preparation.  She sent a sanitarian to block off the drinking fountain with yellow warning tape.  As expected, this inconvenienced hundreds of beachgoers that holiday, and Ms. Baisley gave interviews to the newspaper and the television news.  “It’s not disease-causing bacteria, but it’s not considered safe to drink any kind of water with bacteria in it”, she told them.  “For precautionary reasons, I don’t want to take any chances”.  “Of course, why couldn’t this happen on a regular week?” she lamented.

Back in London, Dr. Snow made a map of the cholera cases, showing how they were clustered around the Broad Street Pump.  He took this to the local Board of Guardians, and this evidence convinced them to disable the pump. Public reaction is not recorded, but the neighborhood residents now had to walk farther away to get their water.  The epidemic then subsided, but whether it was due to the disabling of the pump or was going away of its own accord has not been proven.  In any case, he wrote: “The result of this inquiry, then, is that there has been no particular outbreak or prevalence of cholera in this part of London except among the persons who were in the habit of drinking the water of the above-mentioned pump.”

The Broad Street Pump incident is one of the founding stories of public health.  Dr. John Snow is known as the founder of epidemiology, which is the study of how diseases move through populations.  One hundred and fifty- eight years later, Mrs. Yvette Ghannam of the Greenwich Department of Health follows in his footsteps as she pursues a doctoral degree in epidemiology.  She does her daily work in the Department Laboratory, where the results she finds sometimes elicit public health decisions that prove inconvenient.

Sources:

Greenwich Time, July 7, 2012

Wikipedia: John Snow