An investigation by the US Centers for Disease Control (CDC) interviewed the survivors and carried out microscopic autopsies.
Soil, air and water samples from the hotel were analysed. In December DCD laboratory scientist Joseph McDade isolated the bacterium and it was named Legionella pneumophila. The theory was that it had spread via the hotel's air-conditioning system. This could not be proven so long after the event, but later epidemiological studies have advanced our knowledge. When the CDC report appeared the following April, the term Legionnaires' disease was published for the first time.
Legionnaires' disease in the UK
Legionnaire’s disease strikes about 500 people a year in England, killing around one in ten.
There have been several outbreaks:
- 1985 - Stafford District Hospital
- 175 cases and 28 confirmed deaths
- Source of infection: rooftop air-conditioning cooling tower
- 2002 - Forum 28 arts centre, Barrow-in-Furness
- 172 cases and 7 confirmed deaths
- Source of infection: contaminated cooling tower
- 2012 - Warehouse, Stoke-on-Trent
- 19 cases, 1 confirmed death
- Source of infection: the warehouse hot tub
More Legionella facts
- Legionella can spread more than 10 km in the air, according to a Norwegian study
- One in 10 people who get sick from Legionnaires’ disease will die, CDC predicts
- Legionella is found naturally in fresh water environments like lakes and streams, but becomes a health concern when it grows in human-made water systems
- People contract Legionnaires’ disease by inhaling small water droplets in the air that contain the bacterium
- Six per cent of domestic properties have dangerously high levels of the bug, according to the International Journal of Hygiene and Environmental Health - equivalent to 1.5 million UK households
- 693 cases of Legionnaires’ disease were reported in 2017
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