LEGIONELLA - World Health Organization

Chapter 10 Regulatory aspects
David Cunliffe
Two complementary types of regulatory approach can be applied to legionellosis:
• preventing risk from systems that can support the growth and dissemination of Legionella
• notification of illness.
The water safety plan (WSP) approach (WHO, 2004) provides an appropriate mechanism for
implementing preventive risk management systems, and should form the basis of guidelines
or regulations developed for controlling Legionella.
WSPs incorporate multiple barriers; in the case of Legionella, this approach should focus on
the events that, combined, are prerequisites for most waterborne Legionella infections. These
events include:
• survival and growth of virulent organisms
• inhalation of aerosols
• aspiration
• exposure of susceptible hosts.
Each of these factors can be influenced by management practices, and hence can be subject
to regulation.
Disease notification systems provide a basis for initiating investigations, identifying sources of
infection, issuing public advice and limiting the scale and recurrence of outbreaks. Notification
and investigation systems can be incorporated within regulations.
10.1 Existing guidelines and regulations for risk prevention
Many countries have developed guidelines or regulations for the control of Legionella in water
systems and for the prevention of legionellosis. Guidelines are advisory, whereas regulations
and codes of practice have a more formal standing and are supported by legislative enforcement
(including, in the case of regulations, specific information on managerial responsibility and
operator competency).
• Guidelines include NHMRC (1988); CDC (2003); Allegheny County Health Department
(1997); ASHRAE (2000); Ehrlich, Steele & Sabatini (2000); Standards Association of
Australia/Standards Association of New Zealand (2002); EWGLINET (2003); and WHO
(2004, 2006).
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS