Getting a Handle on Public Health

Dr. Snow used scientific reasoning to find a simple solution to a deadly epidemic. Photo by erix on Flickr.

Based on my non-scientific analysis based on the number of raised eyebrows when attempting to explain what an MPH is- I’ve come to understand a many don’t know what a public health is. There is there is even a campaign to clear up the confusion.

“Public Health is the science of protecting and improving the health of communities through education, promotion of healthy lifestyles, and research for disease and injury prevention. Public health professionals analyze the effect on health of genetics, personal choice and the environment in order to develop programs that protect the health of your family and community.”

The profession is in part to blame for this- public health professionals wear many hats, play many roles, and are active in many arenas. Going back to one of the origins of public health- John Snow and the Broad Street Pump- can provide some clarity.

In 1854 London was being ravaged by a cholera epidemic.  The accepted belief by most, including physicians, was the disease was caused by bad air, or “miasma.”  Inhalation of miasma would result in falling sick with cholera.  Since miasma was believed to be a product of the environment, little effort was made to prevent the disease.

Dr. John Snow, now known as one of the founders of epidemiology and anesthesiology, had a different perspective. He believed cholera was contracted by ingesting of infectious agents and spread through contaminated water.

In September of 1854 cholera struck the community of Broad Street- killing 500 people in less than ten days after the first case. Dr. Snow sought to test his hypothesis that a contaminated water source was the cause of the outbreak.  To support his hypothesis and disprove the miasma theory, he employed a technique still used by public health professionals today- he mapped the residences of afflicted individuals.

Quickly a pattern emerged. Those who lived near the Broad Street Pump- the community’s public water source- were dying in the greatest numbers.  Had the miasma theory been correct the deaths would have been equally distributed, not clustered near the pump.

Dr. Snow petitioned the area government, and the handle was removed from the pump- rendering it unusable.  The epidemic declined.  Simple rational thought and an even simpler solution spared many from suffering.

A simple map supported the hypothesis a public water pump was to blame for the epidemic.

How does this help define public health?

Public health is a broad umbrella, some professionals specialize in one area like epidemiology, while others, like me, draw on multiple areas to find solutions. The Snow story illustrates much of what public health is about.

First, Dr. Snow was aware of a problem- an epidemic of cholera had broken out.  Public health is currently examining problems such as high rates of diabetes in the Native American community, increased risk of cancer for farm workers, unprecedented rates of childhood obesity, etc.

Second, he formulated a hypothesis about the possible cause.  In the Broad Street case he believed contaminated water was the source of the epidemic- not miasma.

Third, he tested the hypothesis. Using death certificates and interviews he mapped deaths due to cholera.  The cluster of deaths around the pump supported his hypothesis.  Today, in addition to mapping, public health professionals utilize statistical analysis, case-control studies, cohort studies, and others to study and test a hypothesis.

Finally, and this is the area I’m the most interested in, he developed a simple intervention to solve the problem. He simply removed the handle.  Public health professionals and advocates target a broad range of “handles-” from providing stable housing to the homeless as a means to stem the HIV epidemic, to elimination of dangerous substances like asbestos from construction which is responsible for mesothelioma.

So what did cause the Broad Street epidemic?

The Broad Street pump was initially contaminated by leakage from a septic tank just 3 feet away. Sewage from the first person, the index case, had been dumped into the tank and seeped into the drinking water.  The socio-economic conditions that lead to a damaged septic tank- that’s for another post.

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