Epidemiologists, Disease Detecting, and Media Literacy

From time to time a small outbreak of an uncommon disease occurs — often in an unexpected location. Sometimes it’s publicized and we hear about it, but at other times the outbreak is small enough that most people only hear after the fact. Either way, many of our elderly parents, and many of us, find out about these outbreaks while watching television, and the news reports are often hyped and scary. All of us need to develop the skill to seek more information and figure out what is left out of a news report.

Click here to learn about a career in epidemiology.

Rarely do such short television news stories explain the extraordinary successes of disease detection and disease detectives — how they collect facts, put them together, and puzzle out possible answers. The people in charge of this process are epidemiologists, scientists, sometimes but not always physicians, who explore the way a disease moves from place to place and how it might be controlled.

Legionella bacteria from the National Library of Medicine image gallery.

In January, many of us heard, mostly on TV and radio but also via print and Internet sources, how a small outbreak (eight cases) of Legionnaires’ disease occurred at a hospital in Wisconsin within a short period of time. We heard about this outbreak, which occurred in 2010, because of a journal article, An Outbreak of Legionnaires Disease Associated with a Decorative Water Wall Fountain in a Hospital published in the February 2012 issue of Infection Control and Hospital Epidemiology.

The Wisconsin outbreak is interesting because it illustrates just how fast Wisconsin public health officials (FYI, these are government employees) observed a problem and got started investigating. According to an article in the Milwaukee Journal Sentinel, state health officials realized that even though the numbers were small, more people than usual had been sick with Legionnaires’ in the previous month, so they set about figuring out why.

The article quotes one of the investigators, Seth Foldy, who now works for the Centers for Disease Control and Prevention. “Typically, one or two people in Milwaukee County are diagnosed with Legionnaires’ disease every month,” Foldy said. Public health officials discovered an anomaly.

Read about Legionnaires' disease at MedlinePlus.

Searching for answers, Wisconsin state epidemiologists and the hospital set up a call center, conducting approximately 4,000 phone and in-person interviews with people who had entered the hospital building or worked there. No additional cases were identified.

Public health officials discovered that all eight people with Legionnaires’ disease had been in the same part of the same hospital building during the same 10-day time period. Moreover, the investigators found that each of the eight people who contracted Legionnaires’ disease had been near a decorative water wall fountain in the hospital. Water mist transmits bacteria to people (but not person-to-person), so they zero-in on the decorative fountain.

After considering potential sources for the bacterium, the epidemiologists concluded that exposure to the hospital’s fountain and the mist it created was associated (see my post on association and causation) with every case in the outbreak. When the hospital shut down the fountain and added plants to the space, no other cases occurred. A Washington Post article by Lena H. Sun provides a thorough overview of the entire incident. Also, in a comprehensive radio interview, NPR reporter, Audie Cornish discusses the journal article and investigation with lead author and Wisconsin epidemiologist, Thomas Haupt.

Everyone needs to know how our public health officials go about solving problems, especially disease outbreaks that become public news events. Moreover, it’s important to remember that, no matter how compelling or dramatic television reporting seems to be, a short report is likely capturing only a small snapshot of any public health story.

N.B. People my age may remember the event that gave the disease its name — the 1976 outbreak in Philadelphia where many Legionnaires, people that is, were attending a convention and became ill. Read this article about the outbreak investigation by New York Times reporter and physician Lawrence K. Altman.

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