Infamous Outbreaks: Philadelphia

Legionnaire’s disease is not uncommon in the U.S. today. I am going to tell you how you might get Legionnaire’s disease, but first let me remind you about the outbreak that introduced the world to this serious form of pneumonia.

It was 1976 in Philadelphia at the Bellevue-Stratford Hotel. There were more than 2000 attendees at a Legionnaires’ convention. Most of the attendees were older, male smokers with chronic lung disease — a very high risk group (as we now know) for Legionnaires’ disease. Among the attendees, 221 became ill with severe pneumonia and 34 died. Despite the large cluster of similar illness, no etiology was apparent until the CDC’s Epidemiology Intelligence Service used special culture techniques to grow the bacteria that caused the infections. They named it Legionella pneumophila.

In nature, Legionella live inside amoebas which live in water. Legionnaire’s disease is acquired by inhaling contaminated water. It is more common after it rains.

The better your cellular immune system is, the more bacteria it takes to infect you. The more immune-compromised you are, the easier it is to get Legionnaire’s disease.

One very healthy 20-something patient of mine was using a garden hose to drain lake water out of his boat. He sucked on the sump to get the flow going and accidently aspirated some of the water. He was in the ICU for weeks with a Legionella pneumophila infection.

On the other hand, my father-in-law was very susceptible. He got Legionnaire’s disease when he was receiving therapy for leukemia. Highly susceptible people like that can acquire Legionella without any obvious exposures. They can acquire the disease from their own shower water. He was in the ICU for 5 weeks but made it through both his infection and the leukemia.

At the Bellevue-Stratford Hotel, Legionella pneumophila was growing in the air-conditioning cooling tower on the roof and was disseminated via the air ducts. Many outbreaks since have spread through public buildings this same way, including hospitals.

Winkler G. Weinberg, MD

I have been an Infectious Disease physician for over 3 decades. I am the author of No Germs Allowed!. If you liked this article, check out the book on Amazon.

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