How do people contract Legionella?
The most popular theory is that the organism is
aerosolized in water and people inhale the droplets
containing Legionella. However, new evidence
suggests that another way of contracting
Legionella is more common. “Aspiration” is the
most common way that bacteria enter into the lungs to cause
pneumonia. Aspiration means choking such that secretions in the
mouth get past the choking reflexes and instead of going into the
esophagus and stomach, mistakenly, enter the lung. The protective
mechanisms to prevent aspiration is defective in patients who smoke
or have lung disease. Aspiration now appears to be the most common
mode of transmission.