Legionnaires’ Disease Linked to Some CT Watersheds

In the 21st century, some believe water contamination in the United States is an issue of the past. Advancements in plumbing, sanitation, and water treatment have drastically reduced the number of diseases spread through infected water.

In Connecticut, however, one water-borne illness has stuck around. Commonly referred to as Legionnaires’ Disease, this disease is a type of atypical pneumonia caused by a group of bacteria called Legionella pneumophila, which are naturally found in freshwater. A recent Yale study, lead by Kelsie Cassell at the Weinberger Lab in the Yale School of Public Health, analyzed cases of Legionnaires’ in Connecticut, hoping to find why cases of this disease have actually risen since 1999.

People typically contract Legionnaires’ by breathing in water vapor containing the bacteria. The good news is that most people exposed do not become infected, but the bad news is that there is nothing doctors can do to prevent people who are exposed from becoming infected. No vaccine currently exists; only after a diagnosis is a person given antibiotics. Affected individuals develop a cough, shortness of breath, high fever, muscle aches, and head pain, symptoms similar to the common cold.

And according to Cassell, misdiagnosis of the disease is all too common. Cassell’s current research aims to bring attention to the presence of Legionnaires’ in Connecticut. She collected data on cases of Legionnaires’ from 1999 to 2015, finding that weather patterns and the geographic makeup of the Connecticut watersheds could potentially explain the spike in Legionnaires’. She was particularly surprised to see the correlation between cases and geography.

What does all of this mean for Connecticut? Should we not drink the water? Cassell chuckles at the question—water in the state is still safe. Legionnaires’ is not a death sentence, even if it’s unlikely we’ll ever eradicate the disease. Cassell hopes that her research raises awareness and pushes hospitals to test for the disease more regularly. 


  1. “Legionnaires’ disease.” Wikipedia, Wikimedia Foundation, 3 Feb. 2018,
  2. Hladky, Gregory B. “Legionnaires’ Disease Risk Linked to Certain River Areas in Connecticut.”, 6 Dec. 2017, 
  3. Personal Interview with Kelsie Cassell, Yale School of Public Health
  4. “Rivers Alliance: Connecticut’s United Voice for River Conservation.” CT Watersheds,