LEGIONELLA - World Health Organization

Where treatments involve the inhalation of thermal waters, there is an increased risk of exposure
to legionellae through inhalation directly into the lungs; nebulizers have been shown to be the
source of nosocomial cases (Mastro et al., 1991). Because the use of nebulizers and inhalers
involves inhaling fine aerosols, the devices must be filled with water that does not contain
potential pathogens such as legionellae, and the suitability of such treatments for high-risk
patients must be assessed (see Chapter 6).
8.4 Monitoring
This section should be read in conjunction with Section 3.3.2 of Chapter 3. The steps
involved in monitoring, some of which are discussed below, are to:
• identify control measures (Section 8.4.1)
• monitor control measures (Section 8.4.2)
• validate effectiveness of the WSP.
Adequate controls, implemented and maintained in a well-designed and well-constructed
system, can ensure the safety of a pool, spa or hot tub. Any control system should be validated
and continually monitored to ensure that it works in the pool.
8.4.1 Identify control measures
People who operate hot tubs and pools must fully understand their entire system, and ensure
that it is managed and maintained to reduce the risk of exposure to infectious agents. The
management structure and staff involved will depend on the nature of the premises. Management
systems must be in place to ensure that operators have sufficient knowledge, competence,
experience and resources to understand and control the risks of infectious disease, including
legionellosis. Inadequate management, poor training and poor communication can all contribute
to outbreaks of infectious disease associated with these systems.
Because most hot tubs, spas and swimming pools are operated at temperatures conducive to
the growth of legionellae, temperature control cannot be relied on as a control measure in the
way it can in distribution and other systems. Therefore, the main control measures are cleaning,
operational procedures, disinfection, good source water quality, and maintenance of water quality.
This section should be read in conjunction with Chapter 4, which describes control measures
for such factors as source water quality and temperature.
Source water quality — control measures
The starting point for control of legionellae and other microorganisms is to ensure that the water
used for filling and topping up the pool is of good microbial quality and free from nutrient sources.
0 LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS