50 years since Philadelphia

This month marks 50 years since the event that brought the dangers of Legionella to the public attention and gave rise to the term ‘Legionnaires’ disease’.

From July 21 to July 24, 1976, more than 2,000 members of the Pennsylvania chapters of the American Legion attended their annual state convention at the Bellevue Stratford Hotel on Philadelphia’s Broad Street. In the days that followed, several of the retired servicemen began suffering from mysterious atypical forms of pneumonia. At the time, nobody knew what was causing it.

In August 1976, TIME magazine published ‘The Philadelphia Killer’, covering the mystery illness. The article explored every possibility. A new strain of influenza, swine flu, toxic chemicals, food poisoning, terrorism and even psychological illness were all considered. Scientists, doctors and public health officials were racing to find answers, while the number of cases and deaths continued to rise. Today, we know the cause was Legionella bacteria.

Almost 50 years later, our understanding of Legionella has transformed. We know the bacteria can grow in poorly managed manmade water systems and spread through tiny airborne water droplets. We understand the conditions that allow it to multiply and, most importantly, how to prevent outbreaks through effective risk assessment, monitoring, temperature control, cleaning, disinfection and ongoing water management.

What was once a frightening medical mystery is now a preventable risk when water systems are properly designed, maintained and managed. The story of Legionella isn’t only about one outbreak in Philadelphia. It’s about the decades of research, legislation and good practice that followed, helping to protect millions of people every day.