Summary.A review of pathogenic microorganisms presenting risk of infection in pool based artificial recreational water venues is extracted from the available scientific literature. The microorganisms are grouped both according to their way of spread and their survival and growth strategies and their characteristics relevant for the pool and spa based recreation are discussed. In order to put the proposed risks on a solid basis, among others a ten year excerpt of the waterborne disease statistics of the Centers for Disease Control and Prevention (CDC) is used throughout the article.Key words: man-made water recreational environment, risk of infection, waterborne disease outbreaks, swimming pool, hot tub.Riassunto (Il rischio di contrarre malattie infettive nelle piscine pubbliche. Una rassegna). Viene presentata una sintesi della letteratura scientifica disponibile sui microorganismi patogeni potenzialmente infettivi, in ambienti acquatici ricreativi artificiali, come le piscine. I microorganismi sono raggruppati sia in base alle loro vie di diffusione che in base alle loro strategie di sopravvivenza e di crescita; successivamente vengono discusse le loro caratteristiche più importanti negli ambienti ricreativi considerati, piscine e terme. Per fornire adeguate e solide basi scientifiche ai tipi di rischi presentati, vengono analizzate, oltre ad altri documenti, le statistiche relative a dieci anni di osservazione di malattie legate all'acqua del Centers for Disease Control and Prevention (CDC).Parole chiave: ambienti ricreativi acquatici artificiali, rischio di infezione, epidemie di malattie legate all'acqua, piscine, vasche da idromassaggio.

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Hungary has a large number of thermal baths and spa facilities which attract hundreds of thousands of tourists annually. Until recently, however, the free-living amoebae were not of public health concern. Genotyping of Acanthamoeba species, potential agents of keratitis and granulomatous encephalitis, was carried out in 20 Hungarian public baths for the first time to assess the incidence and molecular diversity of the genus in the country. Our results show that 6.7% of the samples were positive for Acanthamoeba. Of these positive samples, 6.5 and 7% was from sterilized and unsterilized pools, respectively. The 18S rRNA gene investigation of the nine Acanthamoeba strains found reveals that seven belong to the hazardous T4 genotype. The remaining two samples were of the T15 type. All the strains kept growing at 36 °C. Our results underline the need to develop a control system for free-living amoebae and supervise the disinfection of Hungarian public baths.

Hospital tap water is a potential source of pathogenic bacteria associated with nosocomial infections. Infection control should include preventive measures to reduce the risk of waterborne infection. The efficiency of point-of-use water filters in infection control was assessed in the intensive care unit of a Hungarian hospital with long history of nosocomial Pseudomonas aeruginosa cases. All taps in the unit were fitted with disposable point-of-use filters. The incidence of nosocomial P. aeruginosa infections decreased from 2.71 to 0 cases/100 patient days when the filters were in place. Legionnaires' disease was not observed either during or outside the study period. Before the application of the filters, both P. aeruginosa and Legionella sp. were shown to colonize five of the seven taps. Filtration eliminated both bacteria completely, though secondary contamination was observed. Total genome restriction profiling of environmental and clinical P. aeruginosa isolates have shown the ubiquitous presence of a single genotype. The same genotype was detected in five of the seven previous nosocomial cases, which supports the assumption of water-derived infection. The results demonstrate that point-of-use filters are effective and cost-efficient measures in reducing health-care associated infections.

Nosocomial legionellosis is a growing concern worldwide. In Hungary, about 20% of the reported cases are health-care associated, but in the absence of legal regulation, environmental monitoring of Legionella is not routinely performed in hospitals. In the present study, 23 hospitals were investigated. The hot water distribution system was colonized by Legionella in over 90%; counts generally exceeded the public health limit value. Hot water temperature was critically low in all systems (<45 °C), and large differences (3-38 °C temperature drop) were observed within buildings, indicating insuffi cient circulation. Most facilities were older than 30 years (77%); however, new systems (n = 3) were also shown to be rapidly colonized at low hot water temperature. Vulnerable source of drinking water, complex distribution system, and large volume hot water storage increased the risk of Legionella prevalence (OR = 28.0, 27.3, 27.7, respectively). Risk management interventions (including thermal or chemical disinfection) were only effi cient if the system operation was optimized. Though the risk factors were similar, in those hospitals where nosocomial legionellosis was reported, Legionella counts and the proportion of L. pneumophila sg 1 isolates were signifi cantly higher. The results of environmental prevalence of legionellae in hospitals suggest that the incidence of nosocomial legionellosis is likely to be underreported. The observed colonization rates call for the introduction of a mandatory environmental monitoring scheme.