Page 260 - IGC BOOK

Legionella Bacteria

Legionella bacteria are water-loving soil bacteria. The bacteria are hazardous when inhaled
into the lungs, where they cause Legionnaires' disease (also called legionellosis). This can
occur when water systems in a workplace become contaminated with the bacteria and that
contaminated water is then sprayed to create a mist (with living bacteria inside the droplets).

The most common sources for outbreaks of the disease are outdoor cooling towers associated
with air-conditioning systems. Water containing the bacteria is sprayed inside the cooling
tower, then drifts out of the top of the cooling tower and is inhaled by passers-by. These
people may then develop the disease.

Symptoms start as flu-like (fever, headache, muscle pain, etc.) and then progress to
pneumonia. The disease can prove fatal, especially for the elderly, infirm or immuno-
supressed, or if it is not diagnosed early.

Typical controls include:

Management Controls

• Assessment of the risk from Legionella.
• Appointment of a 'responsible person' to carry out risk assessment, manage and
implement the controls.
• Review of control measures.
Practical Controls

• Avoid water temperatures between 20°C and 45°C and conditions that favour bacteria
growth.
• Avoid water stagnation, which can encourage biofilm growth.
• Avoid using material that can harbour bacteria and provide them with nutrients.
• Control the release of water spray.
• Keep water; storage systems and equipment clean.
• Use water (chemical) treatments where necessary.
• Carry out water sampling and analysis.
• Ensure correct and safe operation and maintenance of water systems.

ENSIGN| Unit IG2 – Element 7 – Chemical and Biological 55
Agents