Legionellosis Associated with Recreational Waters: A Systematic Review of Cases and Outbreaks in Swimming Pools, Spa Pools, and Similar Environments

Abstract

Legionella spp. is widespread in many natural and artificial water systems, such as hot water distribution networks, cooling towers, and spas. A particular risk factor has been identified in the use of whirlpools and hot tubs in spa facilities and public baths. However, there has been no systematic synthesis of the published literature reporting legionellosis cases or outbreaks related to swimming/spa pools or similar environments used for recreational purposes (hot springs, hot tubs, whirlpools, natural spas). This study presents the results of a systematic review of the literature on cases and outbreaks associated with these environments. Data were extracted from 47 articles, including 42 events (17 sporadic cases and 25 outbreaks) and 1079 cases, 57.5% of which were diagnosed as Pontiac fever, without any deaths, and 42.5% were of Legionnaires’ disease, with a fatality rate of 6.3%. The results are presented in relation to the distribution of Legionella species involved in the events, clinical manifestations and diagnosis, predisposing conditions in the patients, favourable environmental factors, and quality of the epidemiological investigation, as well as in relation to the different types of recreational water sources involved. Based on the epidemiological and microbiological criteria, the strength of evidence linking a case/outbreak of legionellosis with a recreational water system was classified as strong, probable, and possible; in more than half of the events the resulting association was strong.

Legionella sp. in water systems in public teaching and education facilities in Małopolskie voivodeship in 2016

“…A systematic review of 47 studies published in 1981-2015 indicated that hot tubs, whirlpools and spa pools are an important source of infection with Legionella sp. A study of 1,079 cases of Legionella infection showed that 57.5% of cases were diagnosed as Pontiac fever (no deaths), and 42.5% as a legionella disease, including 6.3% of deaths (14).…”

“…Przegląd systematyczny 47 badań opublikowanych w latach 1981-2015 wskazał, że wanny z hydromasażem, jacuzzi i baseny typu spa stanowią istotne źródło zakażenia bakteriami Legionella sp. Badanie obejmujące 1 079 przypadków zakażenia Legionellą wykazało, iż 57,5% przypadków zostało zdiagnozowanych jako gorączka Pontiac (bez żadnych zgonów), a 42,5% jako choroba legionistów w tym 6,3% przypadków śmiertelnych (14).…”

Analysis of the Kinetics of Swimming Pool Water Reaction in Analytical Device Reproducing Its Circulation on a Small Scale

“…Among the microorganisms that cause serious illnesses in humans are, among others, Escherischia coli, Staphylococcus aureus, Legionella pneumophila, Pseudomonas aeruginosa, Streptococcus spp. ; viruses: Coxsackie, echo viruses, and adenoviruses; infectious hepatitis; numerous protozoa; and fungi [1][2][3][4][5].…”

Recreational Use of Spa Thermal Waters: Criticisms and Perspectives for Innovative Treatments

“…The water of natural spas should be of satisfactory microbiological quality and must be adequately managed to control the exposure of bathers and personnel to infectious agents. Indeed, the literature describes individual cases or outbreaks associated with the use of swimming/spa pools or similar environments, such as hot springs, hot tubs, whirlpools, natural spas, for recreational, wellness or therapeutic purposes [17,18,19,20,21]. Knowledge on pool uses and on composition of the water that supplies the spa is needed for an effective and appropriate management.…”

“…However, it is well known that pools and spas can present a considerable source of infection and other threats to human health [22,28,29]. In particular, several bacteria such as Legionella, Pseudomonas, Mycobacteria , as well as protozoa such as amoebae, algae and other microorganisms can naturally proliferate in the conditions characteristic of thermal waters and, if not managed properly, can become a hazard for users [17,18,19,20,21]. This problem represents a dilemma between treating or not treating natural spa waters and induces several pool managers to add disinfectants into the natural solutions highly rich in salts, resigning the original water properties in favor of safety, even if there is a lack of knowledge on the chemical risks related to the use of disinfectants in these waters.…”