LegionellaInfection Risk from Domestic Hot Water

Abstract

We investigated Legionella and Pseudomonas contamination of hot water in a cross-sectional multicentric survey in Italy. Chemical parameters (hardness, free chlorine, and trace elements) were determined. Legionella spp. were detected in 33 (22.6%) and Pseudomonas spp. in 56 (38.4%) of 146 samples. Some factors associated with Legionella contamination were heater type, tank distance and capacity, water plant age, and mineral content. Pseudomonas presence was influenced by water source, hardness, free chlorine, and temperature. Legionella contamination was associated with a centralized heater, distance from the heater point >10 m, and a water plant >10 years old. Furthermore, zinc levels of <20 μg/L and copper levels of >50 μg/L appeared to be protective against Legionella colonization. Legionella species and serogroups were differently distributed according to heater type, water temperature, and free chlorine, suggesting that Legionella strains may have a different sensibility and resistance to environmental factors and different ecologic niches.

La légionellose

“…Des légionelles sont fréquemment isolées dans l'eau chaude domestique, avec un niveau moyen de contamination dans les prélèvements positifs dépassant légèrement 1 000 UFC/l. C'est ainsi qu'une étude italienne récente retrouve une contamination de l'eau chaude domestique par des légionelles dans 22,6 % des prélèvements [8], tandis que des études anté-rieures finlandaises et allemandes retrouvaient un taux de positivité de 30 % et 26 %, respectivement. Toutes ces études confirment que Legionella pneumophila est de loin l'espèce bactérienne la plus abondante dans l'eau potable ou environnementale.…”

“…La contamination des points d'eau peut intervenir toute l'année. La concentration en certains sels minéraux tels que le cuivre ou le zinc pourrait jouer un rôle dans leur développement [8,9]. Legionella pneumophila est sensible à la chaleur : au-delà de 60 °C, les légionelles sont tuées.…”

Conventional and Alternative Disinfection Methods of Legionella in Water Distribution Systems – Review

“…Studies on occurrence of Legionella in drinking water distribution systems report high overall prevalence of Legionella. For example, in Italy 22.6 % of the surveyed water distribution systems were contaminated with Legionella [11], 26 % in Germany [12], 30 % in Finland [13] and 42 % in Latvia [14]. Results of these studies indicate that Legionella in water distribution systems is still an unsolved problem.…”

Efficient Disinfection of Tap and Surface Water with Single High Power 285 nm LED and Square Quartz Tube

“…Additionally, it could be combined with a solar cell of about 15ˆ15 cm 2 and disinfect water for a family in rural areas of the Third World sufficiently. It should be noted that this disinfected drinking water should be consumed without a large delay.…”

“…One major problem applying these methods is the possible microbial recontamination on the way to the customer. Thus, the water is most likely not sterile when it comes from the tap, but for example, is loaded with Legionella or other pathogen microorganisms [2,3]. That is even often true for water installations in dentist´s or doctor´s practices or hospitals [4][5][6][7].…”