Bicentennial Bacteria

When the Centers for Disease Control and Prevention (CDC) is notified of a disease outbreak, it can usually be identified in a few weeks, and often in only a few days. But the perpetrator of the bewildering illness that plagued the attendees of America's Bicentennial celebration wasn't identified until January 1977, after six exhausting months of investigative failure.

Because the symptoms of the disease didn't show up until the after victims had dispersed from the conference, a link between the convention and the outbreak wasn't made until a week after the conclusion of the convention. By this time, twelve had already been killed. The disease, which affected 221 people total and caused thirty-four deaths, typically lasted seven to ten days and generally ran the following course:

  • Flu-like symptoms: loss of appetite, muscle pains, headache, low-grade fever

  • Chest and abdominal pains, diarrhea, nausea

  • Shaking chills and a spike in fever up to 105F

    Sick man image from Clip Art
  • Dry cough

  • Pneumonia

  • Mental confusion or delirium

After assessing the injured parties, it was found that smokers, alcoholics, the elderly and those with compromised immune systems were more likely to be victimized. Men were also three times more likely to have the disease than women. These are all facts that only complicated the search for answers. The site of the convention, the Bellevue-Stratford Hotel, quickly became the suspected origin of infection. Every sufferer had a connection to this site either through staying at or visiting the hotel, or by walking directly past. Regardless of the gathered information, two questions still lingered: how were individuals becoming infected (visit the Water Worlds page to find out!) and what was causing this debilitating disease?

The CDC worked diligently and based on certain general knowledge regarding infectious disease they were able to rule out some modes of transmission as well move forward in the     identification process.  However, they unfortunately hit one dead end after another. The food and water were tested and produced negative results. Because the disease didn’t spread after the initial outbreak they immediately ruled out person-to-person transmission.  In addition, spreading of the disease via bug bites didn’t fit either.  The lung tissue of the dead victims yielded no microbes.  Testing by toxicologists as well as countless other efforts left the CDC empty handed.   

After months of draining investigations and media scrutiny, the CDC announced its intent to terminate their efforts. Dr. Joseph McDade, a scientist who months earlier had tested lung tissue samples for Rickettsia (the pathogen that causes many severe human diseases such as Rocky Mountain spotted fever), read the report.  In his previous work, he encountered a few rod-shaped bacteria that he simply disregarded at the time.  But because of the lack of success elsewhere, he decided to revisit them because maybe they did hold significance.

He subjected these rod-shaped bacteria to further testing.  He mixed the blood of sufferers and built up antibodies with the suspicious bacteria. This serological test produced the solution to the puzzle that everyone had been trying to solve.  A solution that, in fact, turned out to be an entirely new organism, genus and species! The cause of Legionnaires’ Disease had been finally been identified and was named Legionella pneumophila.

Visit the Microbe Memberships page for the scientific classification of this non-patriotic species of bacteria!