LEGIONELLA - World Health Organization

Spas
“Natural spa”, denotes facilities containing thermal and/or mineral water, some of which
may be perceived to have therapeutic value. Because of their particular water characteristics,
natural spas may receive minimal water-quality treatment.
Hydrotherapy pools
In addition, there are physical therapy pools, in which professionals perform treatments
for a variety of physical symptoms on people with neurological, orthopaedic, cardiac or
other diseases. These are termed “hydrotherapy pools”, and are defined as pools used
for special medical or medicinal purposes. Hydrotherapy pools are not specifically covered
by this document, although many of the principles that apply to swimming pools and hot
tubs will also apply to them. There are also therapy pools containing small fish (Garra
ruffa) which feed on the scaly skin lesions caused by psoriasis. These types of therapy
pools are not covered here.
Source: WHO (2004)
Legionellae have been isolated from swimming pool water and from pool filters (Jeppesen,
Bagge & Jeppesen, 2000; Leoni et al., 2001). However, as at 2005, no recorded outbreak of
Legionnaires’ disease has been directly associated with bathing in swimming pools. In contrast,
hot tubs have been associated with many outbreaks of infectious disease, including Legionnaires’
disease, for which they are the third most common source (Spitalny et al., 1984; McEvoy et al.,
2000; Benin et al., 2002; Den Boer et al., 2002; Fields, Benson & Besser, 2002; Nagai et al.,
2003). The high incidence of outbreaks associated with hot tubs is due to their increased
popularity in recent years. Table 8.1 shows the number of outbreaks related to hot tubs
between 2000 and 2003, in selected countries in Europe.
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS